Pregnancy Weight and Anthropometric Trajectories: The NICHD Fetal Growth Studies

Abstract

ObjectivesMaternal weight and anthropometric trajectories may affect both fetal programming and maternal pregnancy health outcomes. We developed a statistical model that categorized concomitant changes in weight and body composition across gestation. MethodsWe conducted a secondary analysis of a prospective cohort of singletons (n = 2,353) enrolled from 11 US perinatal centers, 2009–2013. Weight, mid-upper arm circumference (MUAC), plus triceps and subscapular skinfold thickness (TSF, SSF) were measured up to 5 times across gestation. Prenatal weights were also abstracted from medical records. Gestational weight change (GWG) trajectories and time-varying, region-specific body composition (MUAC, TSF, SSF) were modeled jointly with a flexible latent class trajectory model, adjusting for prepregnancy BMI. ResultsMost women had prepregnancy normal weight (56.4%), while fewer were classified as overweight (27.2%) or obese (16.4%). Five trajectory patterns for weight and body composition were identified. (1) InitalHighSteadyGain (12.5%) had the highest 1st trimester weight gain and steady gain thereafter, with high model estimated total GWG (36.1 lbs). (2) InitialModerateSlowGain (19.8%) had moderate 1st trimester gain, then slow steady gain with the lowest total GWG (28.7 lbs). InitalHighSteadyGain and InitialModerateSlowGain showed relatively stable MUAC, while SSF and TSF increased in 1st and 2nd trimesters and decreased in 3rd trimester. Other GWG trajectory groups showed (3) 1st trimester weight loss (LossSteadyGain, 8.2%), (4) stability (StableSteadyGain, 21.5%), or (5) low gain (LowSteadyGain, 38.2%), then steady GWG in the 2nd and 3rd trimesters with estimated total GWG of 35.7, 36.8 and 32.8 lb, respectively. Small increases in MUAC and SSF were observed in LowSteadyGain across pregnancy, while TSF increased up to 30 wk and then decreased. LossSteadyGain and StableSteadyGain groups showed similarities in initial MUAC, TSF and SSF measurements with small increases in MUAC and TSF, and moderate increases in SSF over time. ConclusionsJoint modeling of prenatal weight and regional body composition changes identified five trajectory patterns, which offers a more advanced understanding of how these trajectories concomitantly change during pregnancy. Funding SourcesNICHD; HHS.