Weight gain in early, mid, and late pregnancy and hypertensive disorders of pregnancy.

Objective: To examine the relationship of weight change during early, mid, and late pregnancy with the development of a hypertensive disorder of pregnancy (HDP).

Study Design: These data are from a prospective cohort study of nulliparous women with live singleton pregnancies. "Early" weight change was defined as the difference between self-reported pre-pregnancy weight and weight at the first visit (between 6 and 13 weeks' gestation); "mid" weight change was defined as the weight change between the first and second visits (between 16 and 21 weeks' gestation); "late" weight change was defined as the weight change between the second and third visits (between 22 and 29 weeks' gestation). Weight change in each time period was further characterized as inadequate, adequate, or excessive based on the Institute of Medicine's (IOM's) trimester-specific weekly weight gain goals based on pre-pregnancy body mass index. Multivariable Poisson regression was performed to adjust for potential confounders.

Main Outcome Measure: Development of any hypertensive disorder of pregnancy.

Results: Of 8296 women, 1564 (18.9%) developed a HDP. Weight gain in excess of the IOM recommendations during the latter two time periods was significantly associated with HDP. Specifically, trimester-specific excessive weight gain in the mid period (aIRR 1.16, 95% CI 1.01-1.35) as well as in the late period (aIRR = 1.19, 95% CI = 1.02-1.40) was associated with increased risk of developing HDP. The weight gain preceded the onset of clinically apparent disease.

Conclusions: Excessive weight gain as early as the early second trimester was associated with increased risks of development of HDP.