Urinary incontinence among pregnant women in Southern Brazil: A population-based cross-sectional survey.

Urinary incontinence (UI) is a common condition that causes significant harm to the well-being and quality of life of pregnant women. This cross-sectional population-based study aimed to estimate the prevalence and identify factors associated with the occurrence of UI during pregnancy in women living in the municipality of Rio Grande (RS), Southern Brazil, between January 1 and December 31 of 2016, and included all puerperae living in this municipality that had a child in one of the two local maternity hospitals. The previously trained interviewers used a single standardized questionnaire, within 48 hours after delivery to retrieve information on maternal demographic, behavioral and reproductive/obstetric history, as well as socioeconomic status of the household and care received during pregnancy and childbirth. The multivariate analysis followed a previously defined hierarchical model using Poisson regression with robust variance adjustment and prevalence ratio (PR) as a measure of effect. As a result, 2,716 puerperae were identified, of which 2,694 (99.2%) participated in this study. The prevalence of urinary incontinence in the gestational period was 14.7% (95%CI: 13.4%-16.1%). After adjusted analysis, the likelihood of UI occurring varied significantly as per women's characteristics. For example, the PR for the occurrence of UI among women over 30 years of age was 2.05 (95% CI: 1.39-3.01) compared to adolescents. In two other groups of women who had their first pregnancy before the age of 20 or after the age of 30, the PR for UI was 1.36 (95% CI: 1.04-1.76) and 1.59 (95% CI: 1.01-2.51), respectively, when compared to those who became pregnant for the first time between 20 and 29 years of age. Finally, in two other groups of women, namely, those who reached 90 kg and over at the end of pregnancy and those who performed regular physical exercise and reported frequent urinary urgency, the PR was 2.49 (95% CI: 1.74-3.57), and 2.90 (95% CI: 2.10-4.00) compared to those who did not exercise and did not report urinary urgency, respectively. The authors concluded that UI showed a high prevalence in the study population. The identified risk factors can be well administered at primary health care level. The recommendation of regular physical exercise in pregnancy must be reviewed and better investigated with more robust designs because of possible facilitators for the occurrence of UI in this period.

Introduction

Urinary incontinence (UI) is defined as any involuntary loss of urine, and the prevalence increases with advancing age [1]. Its occurrence ranges from 40% to 60% among women, and from 10% to 20% among men [2].

This higher occurrence among women is generally due to their reproductive life [3]. Hormonal changes, enlargement of the uterus, pelvic floor changes during gestation, and trauma suffered during delivery lead to involuntary loss of urine [4-6].

UI during gestation is a significant predictor for its presence in subsequent pregnancies and at a later age [7], which makes it a chronic disease with a substantial deterioration of the quality of life, whether due to discomfort, the need for regular personal hygiene, or insecurity, among others. At a later age, UI leads to isolation, which favors depression and more severe psychiatric conditions [8,9].

While very prevalent, UI has been rarely studied at the population level in Brazil. The few available studies are performed with a minimal number of pregnant women, usually from a single health service, without any type of representativeness at the population level [10-12]. Besides preventing the establishment of actions and programs due to lack of knowledge of the real magnitude of the problem, this situation hinders prevention at the primary level of health care, which contributes to the persistence and severity of this disease, increases suffering, and deteriorates the quality of life of these women, especially in the gestational period and in older age.

This study aims to measure the prevalence and to identify factors associated with the occurrence of UI in the gestational period among puerperae living in the municipality of Rio Grande (RS), Southern Brazil, during 2016.

Materials and methods

Data shown here derive from the 2016 Perinatal Study, which is part of a series of triennial cross-sectional surveys, held in the municipality of Rio Grande since 2007. These evaluations aim to monitor the quality of gestation and delivery care provided in this municipality. The research protocol was submitted and approved by the Health Research Ethics Committee (CEPAS) of the Santa Casa de Misericórdia of Rio Grande (file Nº 30/2015). Data confidentiality, voluntary participation, and the possibility of leaving the study at any time without the need for justification were assured.

Pregnant women should reside in the municipality of Rio Grande (in urban or rural areas), must have had a child in one of the two local maternity hospitals (Santa Casa de Misericórdia or the University Hospital) from January 1 to December 31, 2016, with a birth weight equal to or greater than 500 grams, or with at least 20 weeks of gestational age, to be included in this survey.

The cross-sectional design was used, and mothers were approached only once in the maternity ward within 48 hours after delivery.

Concerning the sample size, two calculations were performed, namely, one to estimate the prevalence, and the other to identify associated factors; in both cases, we added 10% of possible losses, which means, women who did not want to participate in the study or who left the hospital before being invited to participate. In the first sample, the study should include at least 2,334 puerperae, and regarding the second, 2,680 mothers. We used significance level of 95% [13].

The outcome of this study was established by the event of urinary incontinence in the gestational period evaluated by a positive response to the following question: "During this gestation, did you ever lose urine unintentionally?" The information about this study was collected through a single, pre-coded questionnaire applied by interviewers previously trained using tablets and the REDCap (Research Electronic Data Capture) application [14].

Three previously trained interviewers collected data daily. Puerperae were asked to participate in the study, and then the Informed Consent Form (ICF) was signed. Questionnaires were uploaded daily through the REDCap Web platform, and data consistency was checked and immediately corrected. The consistency analysis included the categorization of variables and frequency verification, and was performed using Stata statistical package version 12.0 [15].

Approximately 10% of the interviews were retaken in order to evaluate the quality of the data collected, which was done later by telephone or home visit, where a summary questionnaire was applied. The Kappa concordance index ranged from 0.68 to 0.89.

Results were expressed by the prevalence, and as a measure of effect, we employed the prevalence ratio (PR), whose interpretation is similar to that provided to relative risk, in cohort studies, or odds ratio, in case-control studies. We also used a 95% confidence interval (95% CI), and the p-value of the trend test and the Wald test for heterogeneity [16]. Crude and adjusted analysis was performed using Poisson regression, with robust adjustment for variance [17]. The adjusted analysis was conducted from a previously defined four-level hierarchical model [18]. This adjusted analysis aims to eliminate the effect of confounding factors, that is, it separates the unique and exclusive effect of the variable in question on the endpoint, eliminating the effect of other variables that are not being tested.

These levels were used to determine the order of entry of the variables in the model. At the first level, demographic and socioeconomic variables (age, skin color, living with a partner, schooling, household income and paid work during pregnancy) were included; the reproductive variable (age at the first pregnancy) was entered at the second level; variables related to prenatal and delivery care (number of prenatal consultations, trimester of onset of consultations, delivery type) and nutritional status (weight at the end of pregnancy) were added at the third level. The fourth and last level included variables related to habits and behavior (smoking, coffee consumption, and regular physical activity in the gestational period) and morbidity (urinary urgency). The outcome was the event of urinary incontinence during pregnancy.

All the variables were taken to the multivariate model, and those with a value of p≤0.20 were maintained. Analyses were conducted in the Stata 12.0 program, and the level of significance was 95%.

Results

The National Live Births Information System [19] and the Mortality Information System evidenced 2,716 births whose mothers lived in the municipality of Rio Grande. Of this total, 2,694 were interviewed, revealing a respondent rate of 99.2% (or a loss of 0.8%).

Table 1 shows the distribution of all puerperae by the main characteristics studied. About 14.7% (95% CI: 13.4–16.1) of women reported having urinary incontinence. Of these, 52.3% had stress incontinence, 18.4% urge incontinence, and 29.3% mixed. Also, 8.8% of them started urinary loss in the first trimester of gestation, 27% in the second and 64.2% in the third trimester, and all of them had UI until the end of gestation.

Table 1

Prevalence of urinary incontinence according to some characteristics of puerperal residents in Rio Grande, Brazil, 2016.

Variables	Total (n)
Maternal age (years)
12–19	16.9% (456)
20–29	49.7% (1,340)
≥30 and over	33.3% (898)
Maternal skin color
White	67.0% (1,806)
Brown	22.7% (610)
Black	10.3% (278)
Living with partner	83.6% (2,252)
Household income in minimum wages
0–0.9	8.5% (215)
1–3.9	69.8% (1,775)
≥4	21.7% (553)
Maternal schooling (full years)
0–8	36.7% (990)
9–11	39.8% (1,071)
≥12	23.5% (633)
Engaged in paid work during pregnancy	45.9% (1,237)
Age (years) at first pregnancy
12–19	60.2% (924)
20–29	35.2% (540)
≥30	4.6% (71)
Number of visits
0–5	15.7% (422)
6–11	72.5% (1,954)
≥12	11.8% (318)
Started prenatal care in the first trimester	78.9% (2,094)
Delivery type
Vaginal	45.8% (1,234)
Cesarean	54.2% (1,460)
Weight (kg) at the end of pregnancy
40–69.9	28.7% (754)
70–79.9	26.2% (688)
80–89.9	22.1% (581)
≥90	23.0% (607)
Drank coffee during pregnancy	33.9% (912)
Smoked during pregnancy	20.6% (341)
Engaged in regular exercise during pregnancy	5.7% (154)
Had urinary urgency
Never	61.8% (1,665)
Sometimes	32.7% (881)
Often	5.5% (148)
Prevalence of urinary incontinence	14.7% (396)
Total	100% (2,694)

Table 2 shows the crude and adjusted analysis of the prevalence of the studied variables, and we found five factors associated with the UI event. In the adjusted analysis, the PR for puerperae aged 30 years or older was 2.05 (95% CI: 1.39–3.01) compared to adolescents; mothers who had their first pregnancy aged 30 years or older, or before the age of 20, had PR = 1.59 (95% CI: 1.01–2.51) and 1,36 (95% CI: 1.04–1.76), respectively, compared to those who had their first pregnancy at 20–29 years. In this same table, we found that the higher the weight at the end of pregnancy, the higher the PR for UI occurrence. PR for the occurrence of UI among those weighing 90 kg or more was 1.63 (95% CI: 1.17–2.27) compared to those who had a weight lower than 70 kg at the end of gestation. Finally, regular physical exercise during pregnancy and reporting frequent urinary urgency showed a PR of 2.49 (95% CI: 1.74–3.57) and 2.90 (95% CI: 2.10–4.00) compared to those who did not exercise and did not report urinary urgency, respectively.

Table 2

Prevalence of urinary incontinence by category and crude and adjusted analyses as per the hierarchical model.

Rio Grande (RS), Brazil, 2016.

Level	Variables	Prevalence of urinary incontinence	Prevalence ratio (CI 95%)
			Crude	Adjusted
I	Maternal age (years)		p<0.00	p<0.001
	12–19	8.3%	11.0	*1.0
	20–29	14.3%	01.72 (1.23–2.40	01.64 (1.13–2.38
	≥30	18.5%	)2.22 (1.59–3.10)	)2.05 (1.39–3.01)
	Skin color		p = 0.09	p = 0.26
	White	15.5%	51.0	51.0
	Brown/Black	13.1%	00.84 (0.69–1.03)	00.89 (0.72–1.10)
	Household income in minimum wages		p = 0.02	p = 0.349
	0–0.9	9.3%	81.0	*1.0
	1–3.9	14.9%	01.60 (1.04–2.47	01.38 (0.89–2.15
	≥4	17.2%	)1.85 (1.17–2.91)	)1.35 (0.83–2.20)
	Maternal schooling (full years)		p = 0.058	p = 0.986*
	0–8	12.9%	1.00	1.00
	9–11	14.9%	1.15 (0.93–1.43)	1.02 (0.81–1.28)
	≥12	17.2%	1.33 (1.05–1.69)	1.02 (0.77–1.36)
	Living with partner		p = 0.061	p = 0.600
	Yes	15.3%	1.00	1.00
	No	11.8%	0.77 (0.59–1.01)	0.92 (0.68–1.25)
	Engaged in paid work during pregnancy		p = 0.021	p = 0.383
	Yes	16.4%	1.00	1.00
	No	13.3%	0.81 (0.67–0.97)	0.91 (0.74–1.12)
ii	Age (years) at first pregnancy		p = 0.035	p = 0.031*
	12–19	16.8%	1.19 (0.93–1.54)	1.36 (1.04–1.76)
	20–29	14.1%	1.00	1.00
	≥30	25.4%	1.80 (1.15–2.83)	1.59 (1.01–2.51)
iii	Number of visits		p = 0.033	p = 0.098*
	0–5	12.1%	1.00	1.00
	6–11	14.6%	1.21 (0.91–1.60)	1.12 (0.74–1.68)
	≥12	18.9%	1.56 (1.10–2.20)	1.53 (0.94–2.49)
	Trimester of onset of prenatal care visits		p = 0.061	p = 0.605
	First	15.4%	1.00	1.00
	Second and third	12.2%	0.79 (0.62–1.01)	0.92 (0.66–1.28)
	Delivery type		p = 0.035	p = 0.981
	Vaginal	13.1%	1.00	1.00
	Cesarean	16.0%	1.22 (1.01–1.47)	1.00 (0.79–1.27)
iii	Weight (kg) at the end of pregnancy		P<0.001	p = 0.016*
	40–69.9	11.1%	1.00	1.00
	70–79.9	14.1%	1.27 (0.96–1.66)	1.09 (0.76–1.57)
	80–89.9	16.2%	1.45 (1.10–1.91)	1.27 (0.89–1.82)
	≥90	19.1%	1.72 (1.32–2.22)	1.63 (1.17–2.27)
iv	Drank coffee during pregnancy		P = 0.030	p = 0.632
	Never drank	12.6%	1.00	1.00
	Drank	15.8%	1.25 (1.02–1.53)	1.06 (0.83–1.36)
	Smoked during pregnancy		p = 0.102	p = 0.219
	No	14.3%	1.00	1.00
	Yes	17.6%	1.23 (0.96–1.58)	1.21 (0.89–1.66)
	Engaged in regular exercise during pregnancy		p<0.001	p<0.001
	No	13.7%	1.00	1.00
	Yes	31.2%	2.27 (1.76–2.93)	2.49 (1.74–3.57)
	Had urinary urgency		p<0.00	p<0.001*
	Never	10.6%	11.0	1.00
	Sometimes	18.4%	01.74 (1.43–2.12	1.74 (1.36–2.22)
	Often	39.2%	)3.71 (2.90–4.73)	2.90 (2.10–4.00)

* Wald trend test.

Discussion

This study found a prevalence of UI in the gestational period of 14.7%. It also showed that the likelihood of this disease, even after adjustment, is significantly higher among pregnant women who got pregnant or had a child in adolescence, who weighed 90 kg or more at the end of gestation, who performed regular physical exercises and who reported frequent urinary urgency during the gestational period.

The prevalence of UI found in this survey is low compared to other studies, ranging from 15% [20] to 71% [11]. This enormous discrepancy arises from different characteristics of the participants, such as the inclusion of nulliparous alone, and the diagnostic criteria used, often based on a single question of the event of involuntary urine loss [21-23].

Maternal age is an inexorable marker of the occurrence of UI. The more advanced the age, the higher its prevalence. This may be due to the loss of innervation and the gradual reduction in the contraction capacity of muscle fibers and increased permeability of the urethral sphincter [24], which leads to a lower pressure of its closure [25], resulting in the involuntary loss of urine. A recent systematic review conducted in the European population found OR = 1.4 (95% CI: 1.3–1.5) for UI among those 35 years of age or older compared to younger age [20]. A similar result was found in this study. Mothers aged 20–29 years and 30 years or older showed a PR for UI of 1.64 (95% CI: 1.13–2.38) and 2.05 (95% CI: 1, 39–3.01), respectively. This evidences the strength of the variable age as a risk factor for this condition.

Maternal age at the time of the first gestation was also significantly associated with the probability of UI in the studied population. A similar finding was found in a cross-sectional study conducted in Norway with about 11,000 women [26]. In this study, women with gestation before 25 years of age showed a prevalence of UI of 23% versus 28% among those who had a child at a later age (p> 0.001). In this study from Rio Grande, having a child at 20–29 years showed the lowest risk of UI compared to those who had a child before the age of 20 or after the age of 30, which is probably due to pelvic floor trauma at younger ages and loss of muscle fibers and urethral sphincter pressure at later ages.

In this study, weighing over 90 kg at the end of gestation showed PR = 1.63 (95% CI: 1.17–2.27) compared to the others. The relationship between body mass index (BMI) and UI is usually directly proportional. This risk factor is already well established [27,28], which may not only be due to the relationship between weight and height but also that the gestational period shows an increased bone density and peripheral edema, and is also influenced by hormonal factors and fetal weight. This set of factors may be responsible for increased weight gain being a significant risk factor for UI.

In Rio Grande, even after adjustment, regular physical exercise appeared as a predisposing factor to UI concerning the other pregnant women, which is even more worrying because obstetricians usually recommend physical exercise, called "fitness", to pregnant women during pregnancy. They claim the benefits of this practice to maternal-fetal health and, because of this, are included in several guidelines as a healthy measure for gestation [29].

It is well known that, even at a young age, elite female athletes have a higher prevalence of UI. This prevalence can affect about half of them [30]. A Norwegian study conducted among academy instructors, including Pilates and Yoga teachers, found a prevalence of UI of 26.4% among instructors with a mean age of 32.8 years (± 8.3). This rate is very similar to that observed in the general female population [31]. These data suggest that physical exercises can overload the pelvic floor, thus increasing the likelihood of UI. In the case of pregnant women, who already have an overload, this is even more serious. Hence the need for this indication to be very well-defined, mentioning exactly which exercises, their frequency, and at what time of gestation they can be performed. Otherwise, this indication may favor UI. It should be noted, however, that when the exercise is directed to the pelvic floor musculature training (PFMT), it has been effective in reducing the occurrence of UI, with RR = 0.71 (95% CI: 0, 54–0.95) compared to those who did not perform this type of training [32]. Also, on this subject, a meta-analysis showed that PFMT, by reducing labor time, especially in the first and second stages reduces pelvic floor trauma and, therefore, can prevent the occurrence of UI [33].

About 40% of pregnant women in this study reported urinary urgency, that is, a sudden sensation that makes it very hard to postpone urination. Of these, about six percent referred to this condition as “very frequently”. The PR for the probability of UI of this group among those who did not report urinary urgency was very high at 2.90 (95% CI: 2.10–4.00). The association between urgency and incontinence is so close that it was set in the next upper level of the endpoint, showing the relevance of this condition to the occurrence of UI.

Urinary urgency is a widespread problem among pregnant women. A Brazilian study found a prevalence of this condition in 44% of the participants [34]. The main reason for urinary urgency is the increased blood volume and the effect of circulating hormones during pregnancy [35], but this should be clarified better.

We should consider that this is a cross-sectional study when interpreting these results. Therefore, caution should be exercised when evaluating some associations because the exposure and outcome variables were collected at the same time. However, we could not find in the literature a more robust design that has worked with such a significant number of pregnant women like this one.

Conclusions

This population-based study showed that urinary incontinence is a common disease among pregnant women, and also confirmed the findings of other investigations for maternal age and urinary urgency as a risk factor for this ailment. It suggested that the variables "age at first gestation", "weight over 90 kg at the end of pregnancy", and "engaging in regular physical exercise in this period" may be associated with this disease as well. As a result, we recommend that professionals providing prenatal care pay attention to these factors, and suggest that these three variables be included in future research on this topic when adopting a more robust design such as a cohort.

11 Mar 2020

PONE-D-19-28652

Urinary incontinence among pregnant women in Southern Brazil a population-based cross-sectional survey

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Reviewer #1: As stated on p. 15, urinary incontinence (UI) is common among pregnant women. The proposed article claims that a positive association exist between pregnant women and UI that is measurable within a define set of inclusion criteria as defined on p. 10. The study is significant given the prevalence and occurrence as stated in the article. The study target population involves a population-based cross-sectional survey of mothers who have given birth within a defined gestational period and/or birth weight (20 weeks gestational age and/or ≥500g).

As mentioned in the article, “regarding sample size, two calculations were performed to estimate prevalence and factors associated with UI in pregnant mothers for the proposed study.” Data obtained from retrospective 2016 perinatal surveys was used to identify association factors and estimate prevalence ratio. Adjustments for eventual losses and adjustments for potential confounders were taken into account and well defined.

Informed consent forms were appropriately signed and provided to birth mothers prior to implementing the study. In addition, a signed copy of the informed consent was retained at the hospital.

In terms of data quality and integrity, data management involved follow up telephone calls and home visits to account for consistency of data. As mentioned in the article, approximately 10% of the interviews were retaken to "evaluate the quality of the data collected."

The study power involved the use of multivariate analysis that followed a hierarchical model to link prevalence of the UI to associated variables with adjusted expected outcomes. Based on this model, the study determined the prevalence of UI in gestational period, lowest observed rate of UI in the study population, the highest frequency of urinary urgency among other variables as outlined in the study.

P. 12 The study outcome was clearly defined.

P.19 Reference list clearly demonstrates literature review for relevant systematic review, meta-analysis, REDcap, and essential tools needed for medical statistics on public health related issues.

Reviewer #2: Dear Author!

This is a cross-sectional study aiming at estimating the prevalence of and risk factors for urinary incontinence during pregnancy among women living in Rio Grande, Brasil.

My comments for you are listed below:

General:

Why did you not separate the conditions stress urinary incontinence and urgency urinary incontinence, which are quite different in etiology?

Abstract:

- UI is a frequent pathology = UI is a frequent condition

- Measure the prevalence = estimate the prevalence

Background:

- “…and increases with age” =”…and the prevalence increases with advancing age”

- This is a journal read mainly by health care professionals, it is therefore unnecessary to explain that UI may be experienced by both sexes. What is essential, however, is that you use the background section to focus on why it is important to examine UI in your population, when similar studies have been performed in other populations. Are you f.i. suspecting that women in Rio Grande would be especially prone to UI due to (I am just guessing) heavy rural work or young age at first delivery?

- Rewrite the following, since in its present form it seems like all factors should be present in the same patient: “The probability of occurrence of UI, even after adjustment, was significantly higher among those who were older than 30 years old at current pregnancy, whose first pregnancy was before the age of 20 or after 30, who reached the end of gestation weighing 90 kg or more, who exercised regularly during pregnancy and who reported frequent urinary urgency during the gestational period.”

Methods:

- First paragraph-shorten or remove

- Why cut-off at 20 weeks?

- Power-calculation hard to follow, and must be better described: especially the following part “…ratio between exposed and unexposed/exposed of 15/85, prevalence of disease among the unexposed of 9.8% and 1.6 risk ratio..”

- eventual losses = eventual lost to follow-up/ lost data or deaths?

- Remove repeated statements like, like p.4 “…the following question: "During this gestation, did you ever lose urine unintentionally?" A positive response would mean puerperae had UI during this gestational period.”

- Condense the text from “Three interviewers collected data….” to “…

was performed using Stata statistical package version 12.0. “

- When were the 10% of the interviews retaken? Did you consider recall bias? What happened when the data were inconsistent, which questionnaire was used- the first or the second?

- Explain the advantage of using Poisson regression models in non-longitudinal data instead of regular linear or logistic regression?

- Remove inadequate racial expressions like skin color, white, brown, black etc. (also in results section and tables)

Results:

- Incredible that more than 99% participated voluntarily in a study, how was this possible?

- Do not repeat extensively in text what is in presented the tables

Discussion:

- Modify strong expressions such as “this is due to the loss of….”, rather use “this may be due to..” or similar.

- Great age= old age/ advanced age

Conclusions:

- Avoid the expression causally associated, since to detect causal effects from a cross-sectional study would be very hard.

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Reviewer #1: Yes: Barbara A. Wilson

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

9 Apr 2020

We attached the Response to Reviewers document.

Submitted filename: Response to reviewers.docx

Click here for additional data file.

28 Apr 2020

PONE-D-19-28652R1

Urinary incontinence among pregnant women in Southern Brazil a population-based cross-sectional survey

PLOS ONE

Dear Mr. TING,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process. ALL of the reviewers' comments and concerns must be addressed in your revision.

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We look forward to receiving your revised manuscript.

Kind regards,

Frank T. Spradley

Academic Editor

PLOS ONE

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Abstract revisions were appropriately applied.

As stated on p. 15, urinary incontinence (UI) is common among pregnant women.  The proposed article claimed that a positive association exists between pregnant women and UI that is measurable within a defined set of inclusion criteria as defined on p. 10.  The study is significant given the prevalence and occurrence as stated in the article.  The study target population involves a population-based cross-sectional survey of mothers who have given birth within a defined gestational period and/or birth weight (20 weeks gestational age and/or ≥500g).

As mentioned in the article, “regarding sample size, two calculations were performed to estimate prevalence and factors associated with UI in pregnant mothers for the proposed study.”    Data obtained from retrospective 2016 perinatal surveys was used to identify association factors and estimate prevalence ratio.

Informed consent forms were appropriately signed and provided to birth mothers prior to implementing the study.   In addition, a signed copy of the informed consent was retained at the hospital.

In terms of data quality and integrity, data management involved follow up telephone calls and home visits to account for consistency of data.  As mentioned in the article, approximately 10% of the interviews were retaken to "evaluate the quality of the data collected."

The study power involved the use of multivariate analysis that followed a hierarchical model to link prevalence of the UI to associated variables with adjusted expected outcomes.   Based on this model, the study determined the prevalence of UI in gestational period, lowest observed rate of UI in the study population, the highest frequency of urinary urgency among other variables as outlined in the study.

P. 12 The study outcome was clearly defined.

P.19 The reference list clearly demonstrates literature reviews on public health related issues.

Reviewer #2: Dear Author!

Thank you for the response to my comments and your effort to improve the paper.

I still have a few comments regarding the methods section:

-You do not have to over-explain the power calculation in a statistical sense, however I am asking you to explain or reference your assumptions. Where did the ratio of unexposed/exposed to UI come from? I suppose the power calculation was performed before you started the study and not performed post-hoc?

- The expression “losses” should be briefly explained: for instance: ..losses, including women who did not want to participate in the study or who left the hospital before being invited to participate….

- I still find the entity “skin color” problematic. Since the Brazilian population is ethnically mixed, the genetic importance of skin color is dubious. Because skin color does not have any relevance for your results, and in order to avoid offending readers, I would recommend the removal of this entity. However, I leave the decision to the editor.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files to be viewed.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email us at figures@plos.org. Please note that Supporting Information files do not need this step.

4 May 2020

Dear Reviewer #2

Here are your comments and our answers, thank you for considering our efforts for improving this paper:

- You do not have to over-explain the power calculation in a statistical sense, however I am asking you to explain or reference your assumptions. Where did the ratio of unexposed/exposed to UI come from? I suppose the power calculation was performed before you started the study and not performed post-hoc?

Answer: We made new adjustments to not over-explain the power calculation. However, for answering the question, the calculation of the sample size, we used data published in other studies and a pilot study carried out before the beginning of data collection. The formula used to calculate the sample parameters was this: A/(B+C*E), where: A=Prevalence of outcome; B=Proportion of non-exposed; C=Proportion of exposed; D=Prevalence of outcome among non-exposed; E=Prevalence ratio (Dean AG, Dean JA, Coulombier D, Brendel KA, Smith DC, Burton AH, Dicker RC, Sulliven K, Fagan RF, Arner TG. Epi-Info, Version 6.02: A Word Processing, Database, and Statistics Program for Epidemiology on Microcomputers. Atlanta (GA): Centers of Disease Control and Prevention; 1994). (Line 93 -98)

- The expression “losses” should be briefly explained: for instance: ..losses, including women who did not want to participate in the study or who left the hospital before being invited to participate….

Answer: Done. Line 95 -96.

- I still find the entity “skin color” problematic. Since the Brazilian population is ethnically mixed, the genetic importance of skin color is dubious. Because skin color does not have any relevance for your results, and in order to avoid offending readers, I would recommend the removal of this entity. However, I leave the decision to the editor.

Answer: We reiterate that we do not evaluate ethnicity, but only the color of the skin, for the reasons already explained in a previous message. In Brazil, saying that someone has white, brown or black skin color is not offensive and has been widely used in scientific articles. I kindly ask you to look for articles by Victora CG, Barros FC and other Brazilian authors, where you can see the wide use of this name. If this does not convince the reviewer, then we leave it to the editor to decide.

Submitted filename: Response to reviewers II.docx

Click here for additional data file.

26 May 2020

Urinary incontinence among pregnant women in Southern Brazil: a population-based cross-sectional survey

PONE-D-19-28652R2

Dear Dr. TING,

We are pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it complies with all outstanding technical requirements.

Within one week, you will receive an e-mail containing information on the amendments required prior to publication. When all required modifications have been addressed, you will receive a formal acceptance letter and your manuscript will proceed to our production department and be scheduled for publication.

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With kind regards,

Frank T. Spradley

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #2: All comments have been addressed

**********

2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #2: Dear author!

Regardless of what may be expressed in other Brazilian papers, I find the use of skin colour as an entity hard to swallow.However, I leave the decision upon this issue to the Editor. I have no further comments.

**********

7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #2: No

29 May 2020

PONE-D-19-28652R2

Urinary incontinence among pregnant women in Southern Brazil: a population-based cross-sectional survey

Dear Dr. TING:

I am pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now with our production department.

If your institution or institutions have a press office, please notify them about your upcoming paper at this point, to enable them to help maximize its impact. If they will be preparing press materials for this manuscript, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information please contact onepress@plos.org.

For any other questions or concerns, please email plosone@plos.org.

Thank you for submitting your work to PLOS ONE.

With kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Frank T. Spradley

Academic Editor

PLOS ONE