Although GWG may be important for executive function, maternal BMI has a stronger relation than GWG to both offspring intelligence and executive function. Our findings contribute to evidence linking maternal obesity to long-term child outcomes.

We provide fetal growth velocity data to complement our previous work on fetal growth size standards, and have developed a calculator to compute fetal growth velocity. Preliminary findings suggest that growth velocity adds additional information over knowing fetal size alone.

Our objective was to systematically review the data interrogating the association between gestational weight gain (GWG) and maternal and child health among women with twin gestations. We identified 15 articles of twin gestations that studied GWG in relation to a maternal, perinatal, or child health outcome and controlled for gestational age at delivery and prepregnancy body mass index. A positive association between GWG and fetal size was consistently found. Evidence on preterm birth and pregnancy complications was inconsistent. The existing studies suffer from serious methodological weaknesses, including not properly accounting for the strong correlation between gestational duration and GWG and not controlling for chorionicity. In addition, serious perinatal outcomes were not studied, and no research is available on the association between GWG and outcomes beyond birth. Our systematic review underscores that GWG in twin gestations is a neglected area of research. Rigorous studies are needed to inform future evidence-based guidelines.

Multiple mechanisms appear to link obesity to stillbirth. Interventions to reduce stillbirth among obese mothers should consider targeting stillbirth due to hypertension and placental diseases-the most common causes of fetal death in this at-risk group.

Background Inadequate or excessive total gestational weight gain (GWG) is associated with increased risks of small- and large-for-gestational age births, respectively, but evidence is sparse regarding overall and trimester-specific patterns of GWG in relation to these risks. Characterizing the interrelationship between patterns of GWG across trimesters can reveal whether the trajectory of GWG in the 1st trimester sets the path for GWG in subsequent trimesters, thereby serving as an early marker for at-risk pregnancies. Objective Describe overall trajectories of gestational weight gain across gestation and assess the risk of adverse birthweight outcomes associated with the overall trajectory and whether the timing of GWG (1st trimester versus 2nd/3rd trimester) is differentially associated with adverse outcomes. Study Design A secondary analysis of a prospective cohort of 2,802 singleton pregnancies from 12 U.S. prenatal centers (2009–2013). Small- and large-for-gestational age were calculated using sex-specific birth weight references <5th, <10th or ≥90th percentiles, respectively. At each of the research visits, women’s weight was measured following a standardized anthropometric protocol. Maternal weight at antenatal clinical visits was also abstracted from the prenatal records. Semiparametric, group-based, latent class, trajectory models estimated overall gestational weight gain and separate 1st and 2nd/3rd trimester trajectories to assess tracking. Robust Poisson regression was used to estimate the relative risk of small- and large-for-gestational age outcomes by the probability of trajectory membership. We tested whether relationships were modified by pre-pregnancy body mass index. Results There were 2,779 women with a mean (SD) of 15(5) weights measured across gestation. Four distinct gestational weight gain trajectories were identified based on the lowest Bayesian Information Criterion (BIC) value, classifying 10.0%, 41.8%, 39.2%, and 9.0% of the population from lowest to highest weight gain trajectories, with an inflection at 14 weeks. The average rate in each trajectory group from lowest to highest for 0 to <14 weeks was −0.20, 0.04, 0.21, and 0.52 kg/week and for 14 to 39 weeks was 0.29, 0.48, 0.63, and 0.79 kg/week, respectively; the 2nd lowest gaining trajectory resembled the Institute of Medicine recommendations and was designated as the reference with the other trajectories classified as low, moderate-high or high. Accuracy of assignment was assessed and found to be high (median posterior probability = 0.99, interquartile range 0.99–1.00). Compared with the referent trajectory, a low overall trajectory, but not other trajectories, was associated with a 1.55-fold (95% CI: 1.06, 2.25) and 1.58-fold (95% CI: 0.88, 2.82) increased risk of small-for-gestational age <10th and <5th, respectively, while a moderate-high and high trajectory, were associated with a 1.78-fold (95% CI: 1.31, 2.41) and 2.45-fold (95% CI: 1.66, 3.61) increased risk of large-for-gestational age, respectively. In a separate a...

Background Conventional measures of gestational weight gain (GWG) are correlated with pregnancy duration, and may induce bias to studies of GWG and perinatal outcomes. A maternal weight-gain-for-gestational-age z-score chart is a new tool that allows total GWG to be classified as a standardized z-score that is independent of gestational duration. Our objective was to compare associations with perinatal outcomes when GWG was assessed using gestational age-standardized z-scores and conventional GWG measures. Methods We studied normal-weight (n=522,120) and overweight (n=237,923) women who delivered live-born, singleton infants in Pennsylvania, 2003-2011. GWG was expressed using gestational age-standardized z-scores and three traditional measures: total GWG (kg), rate of GWG (kg per week of gestation) and the GWG adequacy ratio (observed GWG/GWG recommended by the Institute of Medicine). Log-binomial regression models were used to assess associations between GWG and preterm birth and small- and large-for-gestational-age births while adjusting for race/ethnicity, education, smoking, and other confounders. Results The association between GWG z-score and preterm birth was approximately U-shaped. The risk of preterm birth associated with weight gain <10th percentile of each measure was substantially overestimated when GWG was classified using total kg and was moderately overestimated using rate of GWG or GWG adequacy ratio. All GWG measures had similar associations with small- or large-for-gestational-age birth. Conclusions Our findings suggest that studies of gestational age-dependent outcomes misspecify associations if total GWG, rate of GWG, or GWG adequacy ratio are used. The potential for gestational age-related bias can be eliminated by using z-score charts to classify total GWG.

Background Recent data suggest that children of mothers who are obese before pregnancy, or who gain too much weight during pregnancy, may be at an increased risk of cognitive impairments. Methods Mother–infant dyads enrolled in a birth cohort study in Pittsburgh, Pennsylvania (1983–1986), were followed from early pregnancy to 14 years postpartum (n=574). Math, reading and spelling achievements were assessed at ages 6 and 10 years using the Wide Range Achievement Test-Revised, and at age 14 years using the Wechsler Individual Achievement Test Screener. Self-reported total GWG was converted to gestational age-standardised z-scores. Generalised estimating equations were used to estimate the effects of GWG and pre-pregnancy body mass index (BMI) on academic achievement at 6, 10 and 14 years, while adjusting for maternal race, child sex, parity, employment, family income, maternal intelligence, maternal depression, pre-pregnancy BMI (in GWG models only) and the home environment. Results The mean (SD) BMI was 23.4 (5.7) kg/m2 and the mean (SD) GWG reported at delivery was 14.4 (5.9) kg. There was a significant non-linear association between pre-pregnancy BMI and an offspring’s academic achievement. At 6, 10 and 14 years, an offspring’s academic scores were inversely associated with pre-pregnancy BMI beyond 22 kg/m2. High GWG (>1 SD) was associated with approximately 4-point lower reading (adjusted β (adjβ) −3.75, 95% CI −7.1 to −0.4) and spelling scores (adjβ −3.90, 95% CI −7.8 to −0.2), compared with GWG −1 to +1 SD. Conclusions Future studies in larger and socioeconomically diverse populations are needed to confirm maternal weight and weight gain as causal determinants of a child’s academic skills, and whether this effect persists into adulthood.

Background Our objective was to estimate associations between gestational weight gain z-scores and preterm birth, neonatal intensive care unit admission, large- and small-for-gestational age birth (LGA, SGA), and cesarean delivery among grade 1, 2, and 3 obese women. Methods Singleton infants born in Pennsylvania (2003–2011) to grade 1 (body mass index (BMI) 30–34.9 kg/m2, n=148,335), grade 2 (35–39.9 kg/m2, n=72,032), or grade 3 (≥40 kg/m2, n=47,494) obese mothers were included. Total pregnancy weight gain (kg) was converted to gestational age-standardized z-scores. Multivariable Poisson regression models stratified by obesity grade were used to estimate associations between z-scores and outcomes. A probabilistic bias analysis, informed by an internal validation study, evaluated the impact of BMI and weight gain misclassification. Results Risks of adverse outcomes did not substantially vary within the range of z-scores equivalent to 40-week weight gains of −4.3 to 9 kg for grade 1 obese, −8.2 to 5.6 kg for grade 2 obese, and −12 to −2.3 kg for grade 3 obese women. As gestational weight gain increased beyond these z-score ranges, there were slight declines in risk of SGA but rapid rises in cesarean delivery and LGA. Risks of preterm birth and neonatal intensive care unit admission were weakly associated with weight gain. The bias analysis supported the validity of the conventional analysis. Conclusions Gestational weight gain below national recommendations for obese mothers (5–9 kg) may not adversely affect fetal growth, gestational age at delivery, or mode of delivery.