Design: Systematic review and meta-analysis of 29 randomised trials
Population: 17,937 pregnant women
Primary outcome: Incidence of gestational diabetes
Effect: RR 0.88 (95% CI 0.79–0.98); 16.0% vs 17.1%; I² 51%

A meta-analysis in Nutrients (8 October) pooled 29 randomised trials of antenatal nutrition education in 17,937 pregnant women. Gestational diabetes occurred in 16.0% of those offered education and 17.1% of controls, a pooled risk ratio of 0.88.

That is about one case avoided for every 100 women counselled. Heterogeneity was moderate, reflecting very different programmes. Programmes delivered in hospital, built on a defined nutritional model and delivered as intended showed the largest effects, but those are subgroup comparisons.

The finding supports structured dietary advice early in pregnancy, which costs little. It does not show which programme to copy, and the absolute effect is small.

Offer structured dietary advice at booking, especially to women with risk factors for gestational diabetes
Expect a modest effect: about one case fewer per 100 women
Keep screening on the usual schedule; education does not replace the glucose test
In India, where gestational diabetes is common, booking-visit counselling is a low-cost place to start

Why it matters

Prevention of gestational diabetes has few cheap levers, and this is one with randomised evidence behind it.

The statistics, in plain English

A risk ratio of 0.88 (95% CI 0.79 to 0.98) means about a 12% relative reduction, but the upper end of the interval is close to 1, so the true effect could be very small. An I² of 51% says the trials disagreed with each other moderately, so the pooled number averages quite different programmes.