oral Anthropometric Changes over the Course of Pregnancy and Their Association With Adequacy of Gestation Weight Gain

Abstract

Gestational weight gain (GWG) is a normal and expected component of a healthy pregnancy as it reflects the increasing sizeand weight of the products of conception (e.g., fetus, placenta) as well as maternal tissue, blood, extracellular fluid andmaternal fat stores. However, the one component that is malleable, maternal fat stores, has not been well described by adequacyof GWG. The Pregnancy Eating Attitudes Study (PEAS) protocol allows for an examination of how changes in anthropometricindicators during pregnancy vary based on whether GWG is within the Institute of Medicine (IOM) guidelines. Data werecollected on 353 healthy pregnant women (white: 72%; black 15%; other 13%; mean age 30.4yrs), participating in the PEAScohort at the University of North Carolina Prenatal Clinics. Anthropometric indicators (weight, mid upper arm circumference,and skin folds of the triceps, thigh and upper iliac) weremeasured at <12 weeks, 16-22 weeks, and 28-32 weeks’ gestation. Fatgain was calculated using the formula by Paxton et al. 1 as fat gain=0.77 (weight change, kg) + 0.07 (change in thigh skinfoldthickness, mm) – 6.13. Adequacy of GWG was defined using the 2009 IOM guidelines, calculated for the period of observation.ANOVA was used to test for differences in anthropometric changes by baseline BMI and adequacy of GWG. Multiple logisticregression was used to examine the relationship of changes in anthropometrics, including fat gain, with adequacy of GWG,adjusting for baseline BMI. On average women gained 8.4 kg from a mean of 9.8 to 30.8 weeks of gestation which correspondedto 132% of the recommended GWG. Overall, 22.4% of women gained inadequately and 46% excessively. All anthropometricindicators were correlated with percent of recommended GWG, with fat gain having the highest correlation (r=0.73). Therewere significant differences in mean changes of anthropometric indicators by maternal BMI and adequacy of GWG. Amongobese women as well as among those who gained inadequately all anthropometric indicators were in the negative direction(not including weight gain). Logistic regression results illustrated significant associations between inadequate weight gain andchanges in mid-upper arm circumference, thigh and upper iliac skinfolds while excessive weight gain was only associated withchanges in triceps skinfolds. Fat gain was associated with both inadequate and excessive weight gain. In summary, these dataillustrate that anthropometric changes over the course of pregnancy differ by maternal BMI and are associated with adequacyof GWG.