Effect of antenatal dietary interventions in maternal obesity on pregnancy weight-gain and birthweight: Healthy Mums and Babies (HUMBA) randomized trial

Background Pregnancy interventions that improve maternal and infant outcomes are urgently needed in populations with high rates of obesity. We undertook the Healthy Mums and Babies (HUMBA) randomized controlled trial to assess the effect of dietary interventions and or probiotics in a multiethnic population of pregnant women with obesity, living in an area of high deprivation. Objectives To determine whether a culturally tailored dietary intervention and or daily probiotic capsules in pregnant women with obesity reduces the co-primary outcomes of (1) excessive gestational weight gain (mean >0.27 kg/week) and (2) birthweight. Study Design We conducted a 2 × 2 factorial, randomized controlled trial in women without diabetes at pregnancy booking, body mass index ≥30 kg/m2, and a singleton pregnancy. At 12+0 to 17+6 weeks’ gestation, eligible women were randomized to a dietary intervention (4 tailored educational sessions at ≤28 weeks’ gestation by a community health worker trained in key aspects of pregnancy nutrition plus text messaging until birth) or to routine dietary advice; and to daily capsules containing either (Lactobacillus rhamnosus GG and Bifidobacterium lactis BB12, minimum 6.5 × 109 colony forming units), or placebo, until birth. Analysis was by intention to treat with adjustment for maternal baseline body mass index. Infant outcomes were additionally adjusted for ethnicity, sex, and gestational age at birth. Results In total, 230 women were recruited between April 2015 and June 2017 (dietary intervention N = 116 vs routine dietary advice N = 114; probiotics N = 115 vs placebo N = 115). Baseline characteristics and demographic variables were similar across all groups. There was no significant difference between intervention groups, for the co-primary outcomes of (1) proportion of women with excessive gestational weight gain (dietary intervention vs routine advice: 79/107 [73.8%] vs 90/110 [81.8%], adjusted relative risk [relative risk, 0.92; 95% confidence interval, 0.80–1.05]; probiotics versus placebo: 89/108 [82.4%] and 80/109 [73.4%], relative risk, 1.14, 95% confidence interval, 0.99–1.31) or (2) birthweight (dietary intervention vs routine advice: 3575 vs 3612 g, adjusted mean difference, –24 g, 95% confidence interval, –146 to 97; probiotics vs placebo: 3685 vs 3504 g, adjusted mean difference, 107 g, 95% confidence interval, –14 to 228). Total maternal weight gain, a secondary outcome, was lower with dietary intervention compared with routine dietary advice (9.7 vs 11.4 kg, adjusted mean difference, –1.76, 95% confidence interval, –3.55 to 0.03). There were no significant differences between intervention groups in other secondary maternal or neonatal outcomes. Conclusion Although dietary education and or probiotics did not alter rates of excessive gestational weight gain or birthweight in this multiethnic, high-deprivation population of pregnant women with obesity, dietary education was associated with a modest reduction in total weight gain with potential future benefit for the health of mothers and their offspring if sustained.