Poster Topical Area: Maternal, Perinatal and Pediatric Nutrition
Location: Hall D
Poster Board Number: 411
Objectives: Pregnancy weight gain trajectories are potentially modifiable, and may reflect uterine milieu and nutrient availability to support fetal growth; however, evaluating weight gain over time is challenging to implement and interpret in practice. We sought to describe pregnancy weight gain trajectories with semi-parametric methods.
Methods: Data are from a prospective cohort (n=492) of African American (45.9%) and Dominican (54.1%) women from Northern Manhattan and the South Bronx enrolled during the third trimester from 1998 to 2006. Prepregnancy weight was self-reported, and pregnancy weight data was abstracted from participant medical charts. In women with >3 observations, we fit a latent-class trajectory model with splines and individual random slopes; prepregnancy BMI was used to predict class membership. Rates for each class by trimester were calculated by predicting weight gain for each latent class, and fitting a linear regression on the sets of trimester predictions.
Results: Before pregnancy, 50.6% of women were normal weight, 22.8% overweight, 21.5% obese and 5.1% were underweight. Overall, 5 distinct trajectory classes were identified (Figure). A majority of women (49.8%) were in the 1) LowSteady group with gain of 0.6 lb/wk in first trimester, 1.4 lb/wk in 2nd trimester, and 1.1 lb/wk in 3rd trimester. About a quarter of women (28.0%) were in the 2) SteadyGain group with steady weight gain across pregnancy (1.2 lb/wk in 1st trimester, 0.9 lb/wk in 2nd trimester, and 0.7 lb/wk in 3rd trimester). About 9.8% of women were in the 3) LossSteadyHigh group with loss of 0.3 lb/wk in 1st trimester, and gain of 1.7 and 2.4 lb/wk in 2nd and 3rd trimesters, respectively. 4) HighLowSteady (10.0%) showed gain of 2.4 lb/wk in 1st trimester, 0.6 lb/wk in 2nd trimester, and 0.9 lb/wk in 3rd trimester. Few women (2.4%) were in the 5) HighStableSteady group with very high initial gain and then minimal gain in 2nd trimester, and 0.8 lb/wk in 3rd trimester.
Conclusions: Our results suggest that semi-parametric methods can offer a more nuanced understanding of pregnancy weight trajectories to support clinical management of pregnancy weight gain and evidence based guidelines.
University of Texas at Austin