Do current pregnancy weight gain guidelines balance risks of adverse maternal and child health in a United States cohort?

Abstract

Background: The Institute of Medicine pregnancy weight gain guidelines were developed without evidence linking high weight gain to maternal cardiometabolic disease and child obesity. The upper limit of current recommendations may be too high for the health of the pregnant individual and child.

Objectives: The aim of this study was to identify the range of pregnancy weight gain for pregnancies within a normal body mass index (BMI) range that balances the risks of high and low weight gain by simultaneously considering 10 different health conditions.

Methods: We used data from an United States prospective cohort study of nulliparae followed until 2 to 7 y postpartum (N = 2344 participants with a normal BMI). Pregnancy weight gain z-score was the main exposure. The outcome was a composite consisting of the occurrence of ≥1 of 10 adverse health conditions that were weighted for their seriousness. We used multivariable Poisson regression to relate weight gain z-scores with the weighted composite outcome.

Results: The lowest risk of the composite outcome was at a pregnancy weight gain z-score of -0.6 SD (standard deviation) (equivalent to 13.1 kg at 40 wk). The weight gain ranges associated with no more than 5%, 10%, and 20% increase in risks were -1.0 to -0.2 SD (11.2-15.3 kg), -1.4 to 0 SD (9.4-16.4 kg), and -2.0 to 0.4 SD (7.0-18.9 kg). When we used a lower threshold to define postpartum weight increase in the composite outcome (>5 kg compared with >10 kg), the ranges were 1.6 to -0.7 SD (8.9-12.6 kg), -2.2 to -0.3 SD (6.3-14.7 kg), and ≤0.2 SD (≤17.6 kg). Compared with the ranges of the current weight gain guidelines (-0.9 to -0.1 SD, 11.5-16 kg), the lower limits from our data tended to be lower while upper limits were similar or lower.

Conclusions: If replicated, our results suggest that policy makers should revisit the recommended pregnancy weight gain range for individuals within a normal BMI range.

Keywords: child health; guidelines; maternal health; obesity; obstetrics; pregnancy; public health recommendations.

FIGURE 1

Confounder-adjusted association between pregnancy weight gain z-score and adverse maternal and child health conditions among pregnancies within a normal BMI range in the Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be Heart Health Study, N = 2344. Predicted probabilities of each adverse health outcome for the pregnant individual and child have been adjusted for participant’s age, education, race and ethnicity, marital status, prepregnancy smoking, gravidity, medical insurance, chronic hypertension, diet quality, nausea and vomiting, binge drinking, sleep satisfaction, resilience, depressive symptoms, anxiety, neighborhood walkability, neighborhood deprivation, proximity to grocery stores, and percent of neighborhood with income below the poverty line. Stillbirth and neonatal death have been omitted due to small numbers of cases. For gestational diabetes and preeclampsia cases, the total weight gain before diagnosis was used to calculate pregnancy weight gain z-scores. The upper x axis refers to the total pregnancy weight gain (kg) that is equivalent to pregnancy weight gain z-scores at 40 wk. Wt, weight.

FIGURE 2

Comparison of confounder-adjusted associations between pregnancy weight gain z-score and an unweighted versus a weighted composite of adverse maternal and child health outcome among pregnancies within a normal BMI range in the Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be Heart Health Study (nuMoM2b-HHS), N = 2344. The association between pregnancy weight gain z-score and the unweighted composite outcome appear in pink and the composite outcome weighted for seriousness appear in blue. The circles represent the adjusted rate ratios and lines represent the 95% confidence intervals (CIs). The referent z-score value for the unweighted outcome model is −0.8 standard deviations and for the weighted outcome model is−0.6 standard deviations. The upper x axis refers to the total pregnancy weight gain (kg) that is equivalent to pregnancy weight gain z-scores at 40 wk. Outcomes included in the composite are gestational diabetes, preeclampsia, unplanned cesarean delivery, >10 kg postpartum weight change, postpartum metabolic syndrome, stillbirth, infant death, preterm birth, small-for-gestational-age birth, childhood obesity. Rate ratios have been adjusted for participant’s age, education, race and ethnicity, marital status, prepregnancy smoking, gravidity, medical insurance, chronic hypertension, diet quality, nausea and vomiting, binge drinking, sleep satisfaction, resilience, depressive symptoms, anxiety, neighborhood walkability, neighborhood deprivation, proximity to grocery stores, and percent of neighborhood with income below the poverty line. For gestational diabetes and preeclampsia cases, the total weight gain before diagnosis was used to calculate pregnancy weight gain z-scores.

FIGURE 3

Confounder-adjusted associations between pregnancy weight gain z-score and a weighted composite of adverse maternal and child health outcomes (including >10 kg postpartum weight increase) with varying thresholds of increased risk (5%, Panel A; 10%, Panel B; 20%, Panel C) compared with a z-score of −0.6 SD (the weight gain z-score where the rate of the outcome was lowest). Pregnancies within a normal BMI range, Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be Heart Health Study (nuMoM2b-HHS), N = 2344. The dark blue markers highlight the z-scores at which risk of the weighted composite outcome was above the designated threshold. The light blue markers highlight the scores at which risk of the weighted composite outcome was within risk threshold. Risk thresholds shown are 5% (Panel A), 10% (Panel B), and 20% (Panel C). The referent value is a z-score of −0.6 standard deviations. The upper x axis refers to the total pregnancy weight gain (kg) that is equivalent to pregnancy weight gain z-scores at 40 wk. The vertical gray dotted line indicates the cut-points for the 2009 Institute of Medicine (IOM) pregnancy weight gain recommendations for normal weight pregnancies. Outcomes included in the composite are gestational diabetes, preeclampsia, unplanned cesarean delivery, >10 kg postpartum weight change, postpartum metabolic syndrome, stillbirth, infant death, preterm birth, small-for-gestational-age birth, childhood obesity. Weighted rate ratios (95% confidence intervals [CIs]) have been adjusted for participant’s age, education, race and ethnicity, marital status, prepregnancy smoking, gravidity, medical insurance, chronic hypertension, diet quality, nausea and vomiting, binge drinking, sleep satisfaction, resilience, depressive symptoms, anxiety, neighborhood walkability, neighborhood deprivation, proximity to grocery stores, and percent of neighborhood with income below the poverty line. For gestational diabetes and preeclampsia cases, the total weight gain before diagnosis was used to calculate pregnancy weight gain z-scores.

FIGURE 4

Confounder-adjusted associations between pregnancy weight gain z-score and a weighted composite of adverse maternal and child health outcomes (including >5 kg postpartum weight increase) with varying thresholds of risk (5%, Panel A; 10%, Panel B; 20%, Panel C) compared with a z-score of −1.1, the lowest risk. Pregnancies within a normal BMI range, Nulliparous Pregnancy Outcomes Study: monitoring mothers-to-be Heart Health Study (nuMoM2b-HHS), N = 2344. The dark green markers highlight the z-scores at which risk of the weighted composite outcome was above the designated threshold. The light green markers highlight the scores at which risk of the weighted composite outcome was within risk threshold. Risk thresholds shown are 5% (Panel A), 10% (Panel B), and 20% (Panel C). The referent value is a z-score of −1.1 standard deviation. The upper x axis refers to the total pregnancy weight gain (kg) that is equivalent to pregnancy weight gain z-scores at 40 wk. The vertical gray dotted line indicates the cut-points for the 2009 Institute of Medicine (IOM) pregnancy weight gain recommendations for normal weight pregnancies. The upper x axis refers to the total pregnancy weight gain (kg) that is equivalent to pregnancy weight gain z-scores at 40 wk. Outcomes included in the composite are gestational diabetes, preeclampsia, unplanned cesarean delivery, >5 kg postpartum weight change, postpartum metabolic syndrome, stillbirth, infant death, preterm birth, small-for-gestational-age birth, and childhood obesity. Weighted rate ratios (95% confidence intervals [CIs]) have been adjusted for participant’s age, education, race and ethnicity, marital status, prepregnancy smoking, gravidity, medical insurance, chronic hypertension, diet quality, nausea and vomiting, binge drinking, sleep satisfaction, resilience, depressive symptoms, anxiety, neighborhood walkability, neighborhood deprivation, proximity to grocery stores, and percent of neighborhood with income below the poverty line. For gestational diabetes and preeclampsia cases, the total weight gain before diagnosis was used to calculate pregnancy weight gain z-scores.