Impact of excessive pre-pregnancy body mass index and abnormal gestational weight gain on pregnancy outcomes in women with chronic hypertension

Objectives: To investigate the effects of excessive pre-pregnancy body mass index (BMI) and abnormal gestational weight gain on adverse outcomes in women with chronic hypertension (CH). Study design: A retrospective cohort study of CH women with singleton pregnancy delivered at our Institution in 2002–2013. Women were categorized as normal, overweight, and obese, according to their pre-pregnancy BMI. Further stratification was based on gestational weight gain (insufficient, adequate, and excessive) as defined by 2009 IOM guidelines. Main outcomes measures: Gestational diabetes, hypothyroidism, superimposed preeclampsia, preterm birth <37 weeks, cesarean section, and delivery of a small or large for gestational age neonate. Results: 309 women met inclusion criteria. Obese women had increased odds of gestational diabetes (aOR, 3.18; 95% CI, 1.46–6.90), hypothyroidism (aOR, 2.41; 95% CI, 1.15–5.54), and superimposed preeclampsia (aOR, 2.36; 95% CI, 1.20–4.65), compared to normal BMI. Overweight women also displayed higher risk of diabetes (aOR 2.19; 95% CI, 1.05–5.03). Insufficient weight gain increased odds of small for gestational age neonate in normal BMI women (aOR, 1.82; 95% CI 1.31–2.07), whereas excessive gain was associated with superimposed preeclampsia in normal BMI patients (aOR, 3.51; 95% CI, 1.16–7.89) and with cesarean delivery in obese women (aOR, 2.96; 95% CI, 1.09–5.81). Conclusions: Excessive pre-conception BMI and abnormal gestational weight gain increase odds of pregnancy complications in CH women. Our results stress the importance of pre-conception counseling for weight normalization in CH women, and support IOM recommendations for adequate weight gain during CH pregnancies.