Dear Editor,We read with great interest the recently published article titled ‘Study the effect of increased maternal BMI on foetal outcome: A prospective observational study’ by Nabnita Patnaik.[1] The study addresses an important public health issue and is well written too. However, there are few issues related to the methodology and the conclusion section which I would like to highlight.First, the study design was mentioned as a descriptive cross-sectional study which itself is contradicting the study type, written in the title. The sampling technique used for the selection of study subjects is not clear; whether it is a consecutive sampling or convenient sample? The year of conducting the study is not mentioned as well as the study period for the same is not specified anywhere in the text which makes it difficult for the reader to put it in perspective.Also, estimation of the sample size was not mentioned which will make it difficult to ascertain if statistical rules are applicable or not and this will also have a bearing on the validity of the study as a whole. In our opinion, it would also have been ideal if operational definitions had been included for the reference of the readers. In this study, the author wants to look for the effect of increased maternal BMI (body mass index) on foetal outcome, but inclusion of pregnant women with co-morbid conditions like PCOS, thyroid disorders and diabetes mellitus will itself affect the study results because these co-morbidities are confounders which might lead to bias.[23]In our opinion, women with other co-morbidites should have been excluded from the study and only women with obesity should have been included as study subjects. After delivery, follow-up was done to see any complications, but specifically till what duration is not mentioned. Besides this, variables are not clearly defined like the time points used for the calculation of mean weight gain and what tools and standard procedures were followed while recording the BMI; which classification was used for interpretation.Confidence interval and P value for the test have been mentioned in the methodology section but we could not find any statistical test used for drawing an inference. Being an observational study, in our view there is also no need to write that.Second, the study finding confirms that maternal obesity is associated with an increased risk of low birth weight; but before drawing such inferences, limitations about study design, absence of comparison group and the role of frequently known confounders such as anaemia should be taken into account.[4] In our opinion, a cohort study or case control study could be a better alternative to draw a valid inference.