Contribution of prepregnancy body mass index and gestational weight gain to adverse neonatal outcomes: population attributable fractions for Canada

Abstract

BackgroundLow or high prepregnancy body mass index (BMI) and inadequate or excess gestational weight gain (GWG) are associated with adverse neonatal outcomes. This study estimates the contribution of these risk factors to preterm births (PTBs), small-for-gestational age (SGA) and large-for-gestational age (LGA) births in Canada compared to the contribution of prenatal smoking, a recognized perinatal risk factor.MethodsWe analyzed data from the Canadian Maternity Experiences Survey. A sample of 5,930 women who had a singleton live birth in 2005-2006 was weighted to a nationally representative population of 71,200 women. From adjusted odds ratios, we calculated population attributable fractions to estimate the contribution of BMI, GWG and prenatal smoking to PTB, SGA and LGA infants overall and across four obstetric groups.ResultsOverall, 6% of women were underweight (<18.5 kg/m2) and 34.4% were overweight or obese (≥25.0 kg/m2). More than half (59.4%) gained above the recommended weight for their BMI, 18.6% gained less than the recommended weight and 10.4% smoked prenatally. Excess GWG contributed more to adverse outcomes than BMI, contributing to 18.2% of PTB and 15.9% of LGA. Although the distribution of BMI and GWG was similar across obstetric groups, their impact was greater among primigravid women and multigravid women without a previous PTB or pregnancy loss. The contributions of BMI and GWG to PTB and SGA exceeded that of prenatal smoking.ConclusionsMaternal weight, and GWG in particular, contributes significantly to the occurrence of adverse neonatal outcomes in Canada. Indeed, this contribution exceeds that of prenatal smoking for PTB and SGA, highlighting its public health importance.

Poor Dietary Quality Is Associated with Low Adherence to Gestational Weight Gain Recommendations among Women in Sweden

“…This association seemed to depend mainly on higher-quality fat intake and a lower intake of discretionary foods. 3 Dietary quality assessed by an index (score 0-12) designed to indicate intake of fibre, fat and discretionary food, where ≤4 points equals poor dietary quality, 5-8 points fair dietary quality and ≥9 points high dietary quality [22]. 4 Pregnancy requires 500 mg of stored iron.…”

“…On the one hand, low GWG increases risk of infant small for gestational age (SGA) [2][3][4] and preterm delivery [1,5]. On the other hand, high GWG increases risk of infant large for gestational age (LGA) [2][3][4], preterm delivery [3], caesarean section (C-section) [5], maternal hypertension [1] and postpartum weight retention [2,6]. Both high and low GWG are associated with higher offspring fat mass during childhood [7].…”

“…GWG is regarded a greater contributor to adverse pregnancy outcomes than maternal body mass index (BMI) [3]. The risks associated with inadequate or excessive GWG are however modified by maternal pre-pregnancy BMI [9].…”

Pregnancy complications and risk of preterm birth according to maternal age: A population‐based study of delivery hospitalizations in Alberta

“…Few studies have reported PAFs for pregnancy complications and PTB, as the predominant focus has been on behavioral factors (eg, substance use) . Comparisons to previous research are hindered by study variation.…”

Review shows that maternal obesity induces serious adverse neonatal effects and is associated with childhood obesity in their offspring

“…The risk of preterm birth before 37 weeks was not, or just slightly, increased by maternal obesity, with a population attributable fraction for high BMI of <5% . In contrast, the risk of preterm birth before 33–32 weeks was significantly increased (Table ).…”