Interaction P values between GWG categories and parental education and infant sex for adverse birth outcomes.

Interaction P values between GWG categories and parental education and infant sex for adverse birth outcomes.</p

Association between different GWG classifications and adverse birth outcomes among women with underweight, normal, overweight or obesity.

Association between different GWG classifications and adverse birth outcomes among women with underweight, normal, overweight or obesity.</p

Comparison of baseline characteristics between mother-infant pairs included into final analysis and those were not.

Comparison of baseline characteristics between mother-infant pairs included into final analysis and those were not.</p

Sensitivity analysis using inverse probability weight to assess the potential of selection bias of the association between different GWG classifications and adverse birth outcomes among women with underweight, normal, overweight or obesity.

Sensitivity analysis using inverse probability weight to assess the potential of selection bias of the association between different GWG classifications and adverse birth outcomes among women with underweight, normal, overweight or obesity.</p

Characteristics of the pregnant women and their offspring (n = 1,239).

Characteristics of the pregnant women and their offspring (n = 1,239).</p

AUC for gestational weight gain recommendation range corresponding to each adverse birth outcome, under IOM, NHC, and z-score, respectively.

AUC for gestational weight gain recommendation range corresponding to each adverse birth outcome, under IOM, NHC, and z-score, respectively.</p

Classification of weekly average gestational weight gain during the second and third trimesters and consistency among different guideline (n = 1,239).

Classification of weekly average gestational weight gain during the second and third trimesters and consistency among different guideline (n = 1,239).</p

Association between different GWG classifications and birth weight and gestational age among pregnant women with normal weight based on Chinese guidelines.

Association between different GWG classifications and birth weight and gestational age among pregnant women with normal weight based on Chinese guidelines.</p

Classification of weekly average gestational weight gain during the second and third trimesters and consistency among different guidelines based on complete eligible data.

Classification of weekly average gestational weight gain during the second and third trimesters and consistency among different guidelines based on complete eligible data.</p

Flowchart.

Several gestational weight gain (GWG) guidelines have been established based on monocenter or multicenter researches. We aimed to examine the associations between categories of GWG under the Institute of Medicine (IOM) recommendation guideline, the Chinese National Health Commission (NHC) guideline, and weight-gain-for-gestational-age z-scores derived from the INTERGROWTH-21st Project and adverse birth outcomes. We used data from an antenatal micronutrient supplementation trial in rural western China between 2002 and 2006. Maternal weekly average GWG during the second and third trimesters was calculated and classified into inadequate, adequate and excessive GWG according to the IOM and NHC, respectively. Weight-gain-for-gestational-age z-scores derived from the INTERGROWTH-21st Project were grouped into three subgroups using two approaches: z-score percentileth, 25th to 75th, >75th and z-score 1 SD. Infant birth weight and gestational age were measured using standard approaches. Generalized linear model with binomial family and logit link was applied to estimate the odds ratio (OR) and 95% confidential intervals (CI) for GWG categories and adverse birth outcomes. Among 1,239 women with normal weight (18.5 kg/m2 to 23.9 kg/m2) during early pregnancy, 18.0% and 34.2% were classified as adequate GWG according to IOM and NHC, respectively. Less than half of Chinese women reached optimal GWG by any recommendation guideline. According to NHC, excessive GWG showed a significant association with macrosomia (OR 3.75, 95% CI 1.03, 13.74), large-for-gestation-age (LGA) (OR 2.12, 95% CI 1.01, 4.45), and inadequate GWG was associated with post-term birth (OR 2.25, 95% CI 1.21, 4.16), compared with adequate GWG. Inappropriate GWG was associated with adverse birth outcomes even among women with normal weight during early pregnancy. The monitoring and interventions of weight status during pregnancy, especially for the second and third trimesters, are of great public health importance for optimal birth outcomes. Additionally, developing guideline of appropriate GWG ranges should account for the traits of regional population.</div