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 aMED 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.