Early pregnancy probiotic supplementation with Lactobacillus rhamnosus HN001 may reduce the prevalence of gestational diabetes mellitus: a randomised controlled trial

Two-centre randomized controlled trial in pregnant women enrolled at 14–16 weeks' gestation in Auckland and Wellington, New Zealand. Participants were not selected for high gestational diabetes risk and were English-speaking, with the cohort including women with a history of allergic disease in themselves or the unborn child’s father. For the HN001 group, 212 participants were randomized; GTT data were available for 184 with IADPSG analysis and 194 for New Zealand definition analyses.

Lactobacillus rhamnosus HN001 was given as capsules at a dose of 6 × 10^9 colony-forming units daily, starting at enrolment in early pregnancy and continued throughout pregnancy; supplementation was extended until 6 months after birth if the participant was still breast-feeding. The comparator was placebo.

Early-pregnancy Lactobacillus rhamnosus HN001 may reduce gestational diabetes mellitus, with the clearest effect under New Zealand diagnostic criteria. Under IADPSG criteria, GDM occurred in 15/184 (8.2%) vs 26/189 (13.8%) with placebo, RR 0.59 (95% CI 0.32, 1.08), P = 0.08. Under New Zealand criteria, GDM occurred in 4/194 (2.1%) vs 13/200 (6.5%) with placebo, RR 0.31 (95% CI 0.10, 0.95), P = 0.03. Fasting glucose was also slightly lower with HN001, difference -0.08 (95% CI -0.15, 0.00), P = 0.048, and infants in the HN001 group had a significantly higher 5-minute Apgar score.

The main GDM result was not statistically significant under IADPSG criteria, and the New Zealand definition finding was attenuated with multiple imputation (P = 0.07). The trial was moderate in size and conducted in a specific New Zealand population of English-speaking pregnant women, which limits generalizability.