Willis SK, Wise LA, Laursen ASD, Wesselink AK, Mikkelsen EM, Tucker KL, Rothman KJ, Hatch EE. Glycemic load, dietary fiber, added sugar and spontaneous abortion in two preconception cohorts. J Nutr. 2023 Jan 14;152(12):2818-26. doi: 10.1093/jn/nxac202

BACKGROUND: Spontaneous abortion, pregnancy loss before the 20th week, has adverse psychological and physical sequelae. Some medical conditions with conditions known to affect insulin sensitivity, including polycystic ovary syndrome and diabetes, may affect risk of spontaneous abortion. No prior studies have examined glycemic load and incidence of spontaneous abortion in populations without conditions known to affect insulin sensitivity.

OBJECTIVES: We prospectively evaluated the association between preconception glycemic load and intake of carbohydrates, dietary fiber, and added sugar and risk of spontaneous abortion.

METHODS: During 2013-2020, we recruited pregnancy planners from Denmark (SnartForaeldre.dk; SF) and the United States and Canada (Pregnancy Study Online; PRESTO). Participants completed a baseline questionnaire and a cohort-specific food frequency questionnaire evaluated for validity. We estimated preconception glycemic load and intake of carbohydrates, dietary fiber, and added sugar from individual foods and mixed recipes. We included 2,238 SF and 4,246 PRESTO participants who reported a pregnancy during the course of the study. SAB data were derived from questionnaires and population registries. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CI).

RESULTS: In the study population, 15% of SF participants and 22% of PRESTO participants experienced SAB. Across both cohorts, there was no appreciable association between glycemic load, carbohydrate quality, dietary fiber, or added sugar intake and SAB. Compared with daily mean glycemic load < 110, the HR for women with daily mean glycemic load ≥ 130 was 0.76 (95% CI: 0.52-1.10) in SF and 1.01 (95% CI: 0.86-1.19) in PRESTO.

CONCLUSIONS: Diets with high glycemic load, carbohydrates, and added sugars were not consistently associated with risk of SAB in parallel analyses of two preconception cohort studies of women, in North America and Denmark.