To study the relationship between pre-pregnancy body mass index (BMI) and weight gain during pregnancy with pregnancy and birth outcomes, with a focus on gestational diabetes and hypertension and their role in the association with fetal growth. We studied 1,884 mothers and offspring from the Eden mother–child cohort.Weight before pregnancy (W1) and weight after delivery (W2) were collected and we calculated BMI and net gestational weight gain (netGWG = (W2 - W1)/(weeks of gestation)). Gestational diabetes, hypertension gestational age and birth weight were collected. We used multivariate linear or logistic models to study the association between BMI, netGWG and pregnancy and birth outcomes,
adjusting for center, maternal age and height, parity and average number of cigarettes smoked per day during
pregnancy. High BMI was more strongly related to the risk
of giving birth to a large-for-gestational-age (LGA) baby
than high netGWG (odds ratio OR [95% CI] of 3.23
[1.86–5.60] and 1.61 [0.91–2.85], respectively). However,
after excluding mothers with gestational diabetes or
hypertension the ORs for LGA, respectively weakened
(OR 2.57 [1.29–5.13]) for obese women and strengthened
for high netGWG (OR 2.08 [1.14–3.80]). Low in comparison
to normal netGWG had an OR of 2.18 [1.20–3.99]
for pre-term birth, which became stronger after accounting
for blood pressure and glucose disorders (OR 2.70
[1.37–5.34]). Higher net gestational weight gain was significantly
associated with an increased risk of LGA only
after accounting for blood pressure and glucose disorders.
High gestational weight gain should not be neglected in regard to risk of LGA in women without apparent risk
factors.