Obesity, weight loss, and pregnancy outcomes.

摘要

In today's Lancet, Eduardo Villamor and Sven Cnattingius1 investigate obesity in pregnancy and, more importantly, address causality. Maternal obesity is associated with various complications in pregnancy, including gestational diabetes, pre-eclampsia, macrosomia, caesarean delivery, and stillbirth.2"5 However, whether such associations are causal or confounded remains less dear. Specifically, is there a biological or anatomical relation between obesity and perinatal outcomes, or do they have a common precursor in the causal chain? The effect of obesity isprobably also confounded by several comorbidities, such as pre-existing, and possibly undiagnosed, type 2 diabetes mellitus and hypertension.The best way to assess a causal relation between obesity and perinatal morbidity would be in a randomised trial, in which women are randomly assigned to obesity as the exposure; such atrial, obviously, cannot be done. Another way is to examine a cohort of women, each with two or more pregnancies, whose weight whenentering each pregnancy might differ.