Ripple Effect of Lifestyle Interventions During Pregnancy on Untreated Partners' Weight.

Objective: Weight-loss interventions have a positive "ripple effect" on untreated partners' weight, but ripple effects in pregnancy are unknown. The objective of this study was to determine whether prenatal lifestyle interventions that reduce gestational weight gain in pregnant women have a positive ripple effect on untreated partners' weight.

Methods: Two clinical trials with the same outcome measures randomly assigned pregnant women to a lifestyle intervention or usual care. Untreated partners were randomly assigned according to their pregnant partner's group allocation and were assessed at study entry (~13 weeks' gestation), 35 weeks' gestation, and 6 and 12 months after delivery.

Results: A total of 122 partners (100% male, 23% Hispanic, 82% married, and 48% with obesity) were randomly assigned to the intervention (n = 59) or usual care (n = 63). There was no intervention or intervention-by-time interaction effect on partner weight (P = 0.795). Partner weight changes were not statistically significant (P = 0.120) from study entry to 35 weeks' gestation (mean 0.19 kg; 95% CI: -0.73 to 1.24) or to 12 months after delivery (mean 0.82 kg; 95% CI: -0.26 to 1.91).

Conclusions: There was no evidence of a ripple effect on partner weight. In a self-selected sample, partners of pregnant women appeared not to experience sympathy weight gain.