Terence T Lao1, Annie S Y Hui2, Lai-Wa Law2, Daljit S Sahota2. 1. Departments of Obstetrics & Gynaecology, The Chinese University of Hong Kong, and Prince of Wales Hospital, Shatin, Hong Kong, China. Electronic address: lao-tt@cuhk.edu.hk. 2. Departments of Obstetrics & Gynaecology, The Chinese University of Hong Kong, and Prince of Wales Hospital, Shatin, Hong Kong, China.
Abstract
OBJECTIVES: To explore the relationship between prior abortion history with incidence of pregnancy hypertensive disorders (PHD), including gestational hypertension (GH) and pre-eclampsia (PE), to determine whether the secular increases in GH and PE in developed countries could be related in part to the decreased incidence of abortion. STUDY DESIGN: A single center retrospective cohort study on primiparous Chinese gravidae managed in 1997-2015 in our hospital. MAIN OUTCOME MEASURES: The occurrence of PHD, GH and PE with respect to the presence or otherwise of prior abortions, with the analysis stratified for risk factors that include advanced age, high body mass index (BMI), history of medical disorders, birth before 34 weeks, and maternal hepatitis B virus (HBV) infection and rubella non-immunity which have been shown to influence the occurrence of PHD in our population. RESULTS: The 23,698 (39.3%) of the 60,335 gravidae in the cohort with ≥ one prior abortion had higher incidence of advanced age, HBV infection, rubella non-immunity, and high BMI, but lower incidence of PHD, GH, PE and birth before 34 weeks gestation. The difference in the incidence of GH and PE between gravidae having one versus those with two or more abortions was minimal, and the effect of abortion on PHD was influenced by the other risk factors. On regression analysis, prior abortion reduced PHD (aRR 0.761, 95% CI 0.684-0.846), GH (aRR 0.660, 95% CI 0.563-0.773), and PE (aRR 0.857, 95% CI 0.745-0.987). CONCLUSIONS: Prior abortion reduces the subsequent development of GH and PE in primiparous women.
OBJECTIVES: To explore the relationship between prior abortion history with incidence of pregnancy hypertensive disorders (PHD), including gestational hypertension (GH) and pre-eclampsia (PE), to determine whether the secular increases in GH and PE in developed countries could be related in part to the decreased incidence of abortion. STUDY DESIGN: A single center retrospective cohort study on primiparous Chinese gravidae managed in 1997-2015 in our hospital. MAIN OUTCOME MEASURES: The occurrence of PHD, GH and PE with respect to the presence or otherwise of prior abortions, with the analysis stratified for risk factors that include advanced age, high body mass index (BMI), history of medical disorders, birth before 34 weeks, and maternal hepatitis B virus (HBV) infection and rubella non-immunity which have been shown to influence the occurrence of PHD in our population. RESULTS: The 23,698 (39.3%) of the 60,335 gravidae in the cohort with ≥ one prior abortion had higher incidence of advanced age, HBV infection, rubella non-immunity, and high BMI, but lower incidence of PHD, GH, PE and birth before 34 weeks gestation. The difference in the incidence of GH and PE between gravidae having one versus those with two or more abortions was minimal, and the effect of abortion on PHD was influenced by the other risk factors. On regression analysis, prior abortion reduced PHD (aRR 0.761, 95% CI 0.684-0.846), GH (aRR 0.660, 95% CI 0.563-0.773), and PE (aRR 0.857, 95% CI 0.745-0.987). CONCLUSIONS: Prior abortion reduces the subsequent development of GH and PE in primiparous women.