Maternal body weight trajectories across the life course and risk of preterm delivery.

We examined the association between life course body weight percentile trajectories and risk for preterm delivery (PTD). Data about women's weight at birth, age 18, and before pregnancy were obtained by retrospective self-report in a cohort of 1410 black women in metropolitan Detroit. Growth mixture models were used to categorize women with similar weight percentile trajectories across these time points. Log-Poisson models were used to examine the association between the trajectory groups and PTD. Four trajectory groups with different beginning and endpoints of their weight percentiles (high-high, high-low, low-high and low-low) best fit the data. The groups with the highest prevalence of PTD were those that started low (low-high, 21%; low-low, 18%). The low-high group had a higher prevalence of PTD than the high-high trajectory group in unadjusted models (prevalence ratio=1.49 [95% confidence interval (CI) 1.11, 2.00]). The association became not significant after adjusting for maternal age at delivery, income, diabetes and hypertension. When compared with the high-high trajectory group, the low-low trajectory seemed to also have a higher prevalence of PTD after adjusting for maternal age at delivery, income, diabetes and hypertension (prevalence ratio=1.35 [95% CI 1.00, 1.83]). Results suggest that a woman's risk for PTD is influenced by her body weight trajectory across the life course.

Changes in adipose tissue distribution during pregnancy in overweight and obese compared with normal weight women.

OBJECTIVE: Differences in body fat distribution contribute to the metabolic abnormalities associated with overweight and obesity; however, such differences have not been adequately explored during pregnancy. Our aim was to compare longitudinal trends in maternal abdominal adipose tissue deposition during pregnancy in overweight/obese compared with normal weight women. STUDY DESIGN: Pregnant women, classified as normal weight (body mass index (BMI) <25 kg m(-2); N=61) or overweight/obese (BMI 25 kg m(-2); N=57), were enrolled in a prospective cohort study starting in the first trimester. Maternal subcutaneous (smin) and preperitoneal (pmax) fat were measured by ultrasound at five time points starting between 6 and 10 weeks gestation. The abdominal fat index (AFI), an established marker of visceral adipose tissue, was calculated as the ratio of pmax to smin. The trajectories of smin, pmax, cumulative fat index (smin plus pmax) and the AFI across pregnancy were analyzed using mixed linear models. RESULTS: The rate of maternal weight gain during pregnancy was significantly lower for overweight/obese women compared with their non-overweight counterparts (P<0.05). Accordingly, the rate of change of pmax and smin differed significantly in normal weight compared with overweight/obese women (P=0.0003 and 0.01, respectively). The cumulative fat index did not change across gestation in normal weight women, whereas it decreased for overweight/obese women (P=0.0005). The log AFI increased across pregnancy in both strata, but significantly more rapidly for normal weight compared with overweight/obese women (P=0.06). CONCLUSIONS: Adipose tissue is preferentially deposited in the more metabolically active visceral compartment as pregnancy progresses. However, this process differs in normal weight compared with overweight/obese women and may contribute to metabolic differences between these groups. Our study is a step toward a more refined description of obesity and its consequences during pregnancy.