Three trajectories of gestational weight gain identified in an Australian twin study.

OBJECTIVES: Gestational weight gain (GWG) has been associated with maternal and child health outcomes, but knowledge of appropriate GWG for twin gestations is limited. STUDY DESIGN: The Peri/Postnatal Epigenetic Twins Study is a prospective twin cohort study of 250 women and their twin children in Melbourne, Australia. We modeled trajectories of GWG using group-based growth modeling and compared these trajectories to GWG categories (within, above, or below current GWG recommendations for twin pregnancy). We fitted robust linear and Poisson regression models to assess associations of maternal pre-pregnancy and gestational exposures with risk of gaining weight outside the recommendations. RESULTS: Of the 250 women enrolled in the PETS, GWG measures were available for 172 women. Forty-seven percent of women had GWG within the current recommendations. We identified three GWG trajectories - 23.6% of women had low GWG throughout pregnancy, 34.5% had average GWG throughout pregnancy, and 42.0% had average initial GWG, followed by high GWG from trimester two until delivery. Gestational diabetes mellitus (GDM) was associated with increased risk of inadequate GWG (RR: 2.40, 95%CI: 1.53, 3.75). Pre-pregnancy obesity (RR: 1.88, 95%CI: 1.09, 3.26) and hypertensive disorders of pregnancy (RR: 2.64, 95%CI: 1.20, 5.81) were associated with increased risk of excessive GWG. CONCLUSIONS: More than half of the women in the PETS did not meet the current GWG recommendations. Women with GDM or hypertensive disorders were more likely to gain weight outside these guidelines. More research is needed to establish comprehensive guidelines for twin pregnancies.

Gestational weight gain is associated with childhood height, weight and BMI in the Peri/Postnatal Epigenetic Twins Study.

Multifetal pregnancies are at risk of adverse maternal, neonatal and long-term health outcomes, and gestational weight gain (GWG) is a potentially modifiable risk factor for several of these. However, studies assessing the associations of GWG with long-term health in twins are rare, and studies which do assess these associations in twins often do not account for gestational age. Since longer gestations are likely to lead to larger GWG and lower risk of adverse outcomes, adjusting for gestational age is necessary to better understand the association of GWG with twin health outcomes. We aimed to explore long-term associations of GWG-for-gestational-age with twin anthropometric measures. The Peri/Postnatal Epigenetic Twins Study (PETS) is a prospective cohort study, which recruited women pregnant with twins from 2007 to 2009. Twins were followed-up at 18 months and 6 years of age. GWG-for-gestational-age z-scores were calculated from pre-pregnancy weight and weight at delivery. We fitted regression models to assess associations of GWG with twin weight, height and BMI at birth, 18 months, and 6 years. Of the 250 women in the PETS, 172 had GWG measured throughout pregnancy. Overall, higher GWG-for-gestational-age z-scores were associated with higher birthweight (ß: 0.32 z-scores, 95% Confidence Interval (95% CI): 0.19, 0.45), BMI (ß: 0.29 z-scores, 95% CI: 0.14, 0.43) and length (ß: 0.27 z-scores, 95% CI: 0.09, 0.45). However, these associations were not observed at 18 months or 6 years of age. GWG was associated with twin length, weight and BMI at birth but not during childhood. Further research is needed to determine the long-term effects of GWG on twin health outcomes.