Recent attempted and actual weight change in relation to pregnancy loss: a prospective cohort study

Objective: To assess weight change and attempted weight loss during the 12–18 months before spontaneous conception in relation to the risk of pregnancy loss. Design: Prospective cohort study. Setting: United States, 2007–2011. Methods: Women (n = 629) who were attempting pregnancy reported at baseline any weight loss attempts over the past 12 months, and their minimum and maximum weights during that time. Follow up lasted one to six menstrual cycles and throughout pregnancy. Using bodyweight measured at 4 weeks’ gestation, participants were categorised as having weight loss ≥5%, weight gain ≥5%, both, or neither, over the previous 12–18 months. Log-binomial models adjusted for potential confounders. Main outcome measures: Risk ratio (RR) and 95% confidence interval (CI) of pregnancy loss. Results: Attempted weight loss was reported by 44% of women and actual weight loss by 11%, but neither was consistently associated with pregnancy loss. The RR for recent weight gain ≥5% was 1.65 (CI 1.09, 2.49). Conclusions: Weight gain over the period spanning 12–18 months pre-conception to 4 weeks’ gestation may increase the risk of pregnancy loss among fertile women with prior pregnancy losses. Attempted and actual weight loss were not associated with pregnancy loss; however, replication is needed from larger studies with data on particular weight-loss methods. Tweetable Abstract: Recent weight gain before and around the time of conception may increase the risk of pregnancy loss.