Prepregnancy dietary patterns and risk of pregnancy loss

Background: Two previous case-control studies observed associations between specific food groups and risk of miscarriage; however, to our knowledge, no previous studies have investigated dietary patterns and risk of pregnancy loss. Objective: We aimed to assess prepregnancy adherence to the alternate Healthy Eating Index 2010 (aHEI-2010), alternate Mediterranean diet (aMED), and Fertility Diet (FD) and risk of pregnancy loss. Design: Our prospective cohort study included 15,950 pregnancies reported by 11,072 women in the Nurses' Health Study II between 1992 and 2009. Diet was assessed every 4 y starting in 1991 by using a validated food-frequency questionnaire. Prepregnancy dietary pattern scores were computed as the sum of a woman's score on each pattern's predefined components. Multivariable log-binomial regression models with generalized estimating equations were used to estimate RRs and 95% CIs. Results: Incident spontaneous abortions and stillbirths were reported in 2756 (17.3%) and 120 (0.8%) pregnancies, respectively. None of the 3 dietary patterns were associated with risk of pregnancy loss. In the multivariable model, RR of pregnancy loss for a 1-SD increase in score was 1.02 (95% CI: 0.98, 1.05) for the a MED pattern, 1.01 (95% CI: 0.98, 1.05) for the aHEI-2010 pattern, and 0.98 (95% CI: 0.95, 1.01) for the FD pattern. Results were consistent when pregnancy loss was classified as either a spontaneous abortion (loss at <20 wk) or a stillbirth (loss at >= 20 wk). Conclusion: Prepregnancy adherence to several dietary patterns was not associated with risk of pregnancy loss.