Effects of dietary counselling on food habits and dietary intake of Finnish pregnant women at increased risk for gestational diabetes - a secondary analysis of a cluster-randomized controlled trial.

The incidence of gestational diabetes mellitus (GDM) is increasing and GDM might be prevented by improving diet. Few interventions have assessed the effects of dietary counselling on dietary intake of pregnant women. This study examined the effects of dietary counselling on food habits and dietary intake of Finnish pregnant women as secondary outcomes of a trial primarily aiming at preventing GDM. A cluster-randomized controlled trial was conducted in 14 municipalities in Finland, including 399 pregnant women at increased risk for developing GDM. The intervention consisted of dietary counselling focusing on dietary fat, fibre and saccharose intake at four routine maternity clinic visits. Usual counselling practices were continued in the usual care municipalities. A validated 181-item food frequency questionnaire was used to assess changes in diet from baseline to 26-28 and 36-37 weeks gestation. The data were analysed using multilevel mixed-effects linear regression models. By 36-37 weeks gestation, the intervention had beneficial effects on total intake of vegetables, fruits and berries (coefficient for between-group difference in change 61.6 g day(-1), 95% confidence interval 25.7-97.6), the proportions of high-fibre bread of all bread (7.2% units, 2.5-11.9), low-fat cheeses of all cheeses (10.7% units, 2.6-18.9) and vegetable fats of all dietary fats (6.1% -units, 2.0-10.3), and the intake of saturated fatty acids (-0.67 energy-%-units, -1.16 to -0.19), polyunsaturated fatty acids (0.38 energy-%-units, 0.18-0.58), linoleic acid (764 mg day(-1), 173-1354) and fibre (2.07 g day(-1) , 0.39-3.75). The intervention improved diet towards the recommendations in pregnant women at increased risk for GDM suggesting the counselling methods could be implemented in maternity care.