Pre-Pregnancy Overweight Status between Successive Pregnancies and Pregnancy Outcomes

Maternal obesity has been positively associated with risk of adverse pregnancy outcomes, but evidence of a causal relation is scarce. Causality would be lent support if temporal changes in weight affected risk of adverse pregnancy outcomes. We examined the associations between change in prepregnancy body-mass index (BMI) from the first to the second pregnancies, and the risk of adverse outcomes during the second pregnancy in a nationwide Swedish study of 151 025 women who had their first two consecutive singleton births between 1992 and 2001. Compared with women whose BMI changed between -1.0 and 0.9 units, the adjusted odds ratios for adverse pregnancy outcomes for those who gained 3 or more units during an average 2 years were: pre-eclampsia, 1.78 (95% CI 1.52-2.08); gestational hypertension 1.76 (1.39-2.23); gestational diabetes 2.09 (1.68-2.61); caesarean delivery 1.32 (1.22-1.44); stillbirth 1.63 (1.20-2.21); and large-for-gestational-age birth 1.87 (1.72-2.04). The associations were linearly related to the amount of weight change and were also noted in women who had a healthy prepregnancy BMI for both pregnancies. These findings lend support to a causal relation between being overweight or obese and risks of adverse pregnancy outcomes. Additionally they suggest that modest increases in BMI before pregnancy could result in perinatal complications, even if a woman does not become overweight. Our results provide robust epidemiological evidence for advocating weight loss in overweight and obese women who are planning to become pregnant and, to prevent weight gain before pregnancy in women with healthy BMIs.

Background The increasing prevalence of obesity in young women is a major public health concern. These trends have a major impact on pregnancy outcomes in these women, which have been documented by several researchers. In a population based cohort study, using routinely collected data, this paper examines the effect of increasing Body Mass Index (BMI) on pregnancy outcomes in nulliparous women delivering singleton babies. Methods This was a retrospective cohort study, based on all nulliparous women delivering singleton babies in Aberdeen between 1976 and 2005. Women were categorized into five groups – underweight (BMI 35 Kg/m2). Obstetric and perinatal outcomes were compared by univariate and multivariate analyses. Results In comparison with women of BMI 20 – 24.9, morbidly obese women faced the highest risk of pre-eclampsia {OR 7.2 (95% CI 4.7, 11.2)} and underweight women the lowest {OR 0.6 (95% CI 0.5, 0.7)}. Induced labour was highest in the morbidly obese {OR 1.8 (95% CI 1.3, 2.5)} and lowest in underweight women {OR 0.8 (95% CI 0.8, 0.9)}. Emergency Caesarean section rates were highest in the morbidly obese {OR 2.8 (95% CI 2.0, 3.9)}, and comparable in women with normal and low BMI. Obese women were more likely to have postpartum haemorrhage {OR 1.5 (95% CI 1.3, 1.7)} and preterm delivery ( 4,000 g was in the morbidly obese {OR 2.1 (95% CI 1.3, 3.2)} and the lowest in underweight women {OR 0.5 (95% CI 0.4, 0.6)}. Conclusion Increasing BMI is associated with increased incidence of pre-eclampsia, gestational hypertension, macrosomia, induction of labour and caesarean delivery; while underweight women had better pregnancy outcomes than women with normal BMI.

To investigate the association between obesity and miscarriage. Meta-analysis. The Academic Unit of Reproductive and Developmental Medicine, The University of Sheffield, United Kingdom. Obese and overweight patients who had miscarriage after spontaneous or assisted conception, compared with patients with a normal body mass index. A systematic review was conducted for all relevant articles in MEDLINE from 1964 to September 2006 and in EMBASE from 1974 to September 2006, using a combination of the following search terms: obesity/obes*/obes$/BMI, miscarriage/abortion/pregnancy, IVF, clomifene/clomiphene, gonadotrophins/gonadotrop*/gonadotrop$. Pregnancy loss at or =25 kg/m(2) had significantly higher odds of miscarriage, regardless of the method of conception (odds ratio, 1.67; 95% confidence interval, 1.25-2.25). Subgroup analysis from a limited number of studies suggested that this group of women may also have significantly higher odds of miscarriage after oocyte donation (odds ratio, 1.52; 95% confidence interval, 1.10-2.09) and ovulation induction (odds ratio, 5.11; 95% confidence interval, 1.76-14.83). There was no evidence for increased odds of miscarriage after IVF-intracytoplasmic sperm injection. There is evidence that obesity may increase the general risk of miscarriage. However, there is insufficient evidence to describe the effect of obesity on miscarriage in specific groups such as those conceiving after assisted conception.