Lifestyle intervention to limit gestational weight gain: the Norwegian Fit for Delivery randomised controlled trial

Objective: To examine whether a lifestyle intervention in pregnancy limits gestational weight gain (GWG) and provides measurable health benefits for mother and newborn.

Design: Randomised controlled trial.

Setting: Healthcare clinics of southern Norway.

Population: Healthy, non-diabetic, nulliparous women, aged ≥18 years, with a body mass index of ≥19 kg/m² , and with a singleton pregnancy at ≤20 weeks of gestation.

Methods: Women were randomised to an intervention group (with dietary counselling twice by telephone and access to twice-weekly exercise groups) or to a control group (with standard prenatal care). Participants were measured three times during pregnancy and at delivery, and newborns were measured at delivery. Hospital records were reviewed for outcomes of pregnancy and delivery. Assessors were blinded to group allocation. Analysis was performed by intention to treat, assessing GWG using the Student's t-test and linear mixed models, and comparing proportions using the chi-square test.

Main outcome measures: GWG, rates of pregnancy complications and operative deliveries, and newborn birthweight.

Results: A total of 606 women were randomised. Of these, 591 were analysed, with 296 in the intervention group and 295 in the control group. At term, the mean GWG from pre-pregnancy was 14.4 kg for the intervention group and 15.8 kg for the control group (mean difference 1.3 kg; 95% confidence interval, 95% CI 0.3-2.3 kg; P = 0.009). There was no significant difference between groups in the frequency of pregnancy complications or operative deliveries. The intervention demonstrated no effect on the mean birthweight of term infants, or on the proportion of large newborns.

Conclusions: The Norwegian Fit for Delivery lifestyle intervention in pregnancy had no measurable effect on obstetrical or neonatal outcomes, despite a modest but significant decrease in GWG.

Tweetable abstract: Norwegian Fit for Delivery RCT: reduced gestational weight gain, unchanged birthweight and obstetric outcomes.