Background: High weight gain in pregnancy has been associated with child adiposity, but few studies have assessed the relationship across childhood or in racially/ethnically diverse populations.

Objectives: To test if weight gain in pregnancy is associated with high birthweight and overweight/obesity in early, middle, and late childhood, and whether these associations differ by maternal race/ethnicity.

Methods: 7539 mother-child dyads were included from NLSY79: a nationally representative cohort study in the U.S. (1979-2012). Log-binomial regression models were used to analyze associations between GWG and the outcomes: high birthweight (> 4000 g) and overweight/obesity at ages 2-5 years, 6-11 years, and 12-19 years.

Results: Excessive weight gain was positively associated and inadequate weight gain was negatively associated with high birthweight after confounder adjustment (P < 0.05). Only excessive weight gain was associated with overweight in early, middle, and late childhood. These associations were not significant in Hispanics or blacks, although racial/ethnic interaction was only significant ages 12-19 years (P = 0.03).

Conclusions: Helping pregnant women gain weight within national recommendations may aid in preventing overweight and obesity across childhood, particularly for non-Hispanic white mothers.

Purpose. To quantify the relationship between pregnancy weight gain with early and late preterm birth and evaluate whether associations differed between non-Hispanic (NH) black and NH white women.

Methods. We analyzed a retrospective cohort of all live births to NH black and NH white women in the U.S. 2011-2015 (n = 10,714,983). We used weight gain z-scores in multiple logistic regression models stratified by prepregnancy body mass index (BMI) and race to calculate population attributable risk (PAR) percentages for the contribution of high and low pregnancy weight gain to early and late preterm birth.

Results. Pregnancy weight gain was related to early and late preterm birth, but associations varied by BMI and race. For early preterm birth, the PAR percentage for high pregnancy weight gain ranged from 8-10% in NH black women and from 6-8% in NH white women. There was little evidence of racial differences in late preterm birth:   PAR percentages ranged from 2-7% in NH black women and from 3-7% in NH white women.

Conclusions. Moderate gestational weight gain is associated with lower rate of  preterm birth, with greatest reductions for early preterm birth in NH black women.

BACKGROUND:

Women's experience of childhood adversity may contribute to their children's risk of obesity. Possible causal pathways include higher maternal weight and gestational weight gain, which have been associated with both maternal childhood adversity and obesity in offspring.

METHODS:

This study included 6718 mother-child pairs from the National Longitudinal Survey of Youth 1979 in the United States (1979-2012). We applied multiple log-binomial regression models to estimate associations between three markers of childhood adversity (physical abuse, household alcoholism, and household mental illness) and offspring obesity in childhood. We estimated natural direct effects to evaluate mediation by prepregnancy BMI and gestational weight gain.

RESULTS:

Among every 100 mothers who reported physical abuse in childhood, there were 3.7 (95% confidence interval: -0.1 to 7.5) excess cases of obesity in 2- to 5-year olds compared with mothers who did not report physical abuse. Differences in prepregnancy BMI, but not gestational weight gain, accounted for 25.7% of these excess cases. There was no evidence of a similar relationship for household alcoholism or mental illness or for obesity in older children.

CONCLUSIONS:

In this national, prospective cohort study, prepregnancy BMI partially explained an association between maternal physical abuse in childhood and obesity in preschool-age children. These findings underscore the importance of life-course exposures in the etiology of child obesity and the potential multi-generational consequences of child abuse. Research is needed to determine whether screening for childhood abuse and treatment of its sequelae could strengthen efforts to prevent obesity in mothers and their children.

Despite improvements in prenatal healthcare, preterm birth remains the leading cause of infant mortality. The causes of preterm birth are not well-understood, especially in Hispanics—who nationally have preterm birth rates comparable to non-Hispanic whites despite socioeconomic disadvantages. Even less understood are the effects maternal nativity may have on the causes of preterm birth. This study aims to assess prepregnancy risk factors for preterm birth in a Hispanic population of WIC participants in Southern California, if prevalence of preterm birth differs by maternal nativity, and whether there is effect measure modification of any associations between risk factors and preterm birth by nativity on the multiplicative scale. Cross-sectional survey data (N = 1174) were collected within one year postpartum and assessed by logistic regression with sampling weights. After adjustment for confounders, risk factors for preterm birth were maternal age 35 or older, and stressful life events among U.S.-born but not foreign-born women. The prevalence of preterm birth in this low-income study population (15.1%) suggests the risk of preterm birth in Hispanic women may be low relative to non-Hispanic black women. Further investigation with large, prospective studies is needed to better understand the causes of and disparities in preterm birth among the growing Hispanic population in the U.S.

Weight and weight change during pregnancy influence fetal growth and development and may have long-lasting effects on offspring health. Additionally, nearly half of women now begin pregnancy overweight or obese and a wide range of weight is gained and lost during and after pregnancy. In response to these concerns, the Institute of Medicine (IOM) revised its gestational weight gain recommendations in 2009 to include a specific, relatively narrow range of recommended gain for women with prepregnancy obesity. Unfortunately, limited scientific evidence and quantitative methods guided these recommendations. The IOM made several research recommendations, including that studies on the impact of gestational weight gain on a range of child outcomes be conducted in large, diverse populations, and that such studies address the extent to which optimal weight gain differs by maternal prepregnancy body mass index (BMI) and other maternal factors, including maternal race/ethnicity.

This dissertation aims to address gaps in our understanding of how pregnancy weight and weight change are associated with child health. The first paper demonstrates two recently developed, quantitative approaches to studying gestational weight gain and determining optimal ranges of weight gain for minimal risk of preterm birth. It also informs whether weight gain recommendations should be tailored to maternal race/ethnicity, which has previously been suggested by the IOM. The second paper identifies longitudinal trajectories of maternal weight from prepregnancy through the postpartum period and assesses the relationship between maternal weight trajectories and offspring obesity in childhood. The third paper determines if maternal history of physical abuse in childhood is related to the risk of offspring overweight in childhood, and whether prepregnancy BMI and gestational weight gain play mediating roles in such an association.

These dissertation papers together provide valuable information to help determine ranges of weight gain during pregnancy that minimize risk of adverse infant and child health outcomes. They also intend to stimulate further research to establish a scientific evidence base for creating effective interventions and clinical gestational weight gain guidelines. Promoting healthy weight and weight gain in pregnancy presents a potentially feasible and effective opportunity to improve infant and child health.

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