IDF21-0336 Longer gestation and reduced birth centile in women who consume a low carbohydrate diet in pregnancy

Abstract

Background: Studies of obstetric outcomes in women consuming low carbohydrate diets have reported conflicting results. The majority of these studies have defined low carbohydrate diets by the percentage that carbohydrates contribute to overall energy intake, rather than by an absolute amount in grams per day. Aim: The aim of this study was to determine if a low absolute carbohydrate diet affects obstetric outcomes differently than a low percentage carbohydrate diet. Method: A cohort study was conducted using detailed dietary data collected in women enrolled in the Study of Probiotic IN Gestational diabetes at both 16 and 28 weeks’ gestation by food frequency questionnaire. Obstetric outcomes were compared between women whose carbohydrate intake was in the lowest quintile and women whose carbohydrate intake was in quintiles 2-5. Carbohydrate intake was firstly assessed in grams per day and secondly as a percentage of total energy consumption. Results: Mean gestation was increased in women whose carbohydrate intake in grams per day was in the lowest quintile at 16 and at both 16 & 28 weeks’ gestation compared with all other women. The difference was greatest when women consumed a low carbohydrate diet at both 16 and 28 weeks’ gestation (16: 39.7 vs 39.1 weeks, p = 0.008; 16 and 28: 39.8 vs 39.1, p = 0.005). Birth centile was decreased in offspring of women whose carbohydrate intake in grams per day was in the lowest quintile at 28 and at both 16 and 28 weeks’ gestation, but not at 16 weeks’ gestation. No differences in gestation at delivery or birth centile were seen in women whose carbohydrate intake was in the lowest quintile when analysed as a percentage of overall energy intake. Discussion: Low absolute carbohydrate intake in pregnancy is associated with different obstetric outcomes from a low percentage carbohydrate intake. Low absolute carbohydrate consumption in pregnancy is associated increased gestational age at delivery and reduced birth centile.