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.