Preconception Plasma Phospholipid Fatty Acids and Fecundability.

Context: Fatty acids (FAs) are important for reproductive processes, including steroidogenesis, though associations with fecundability, as measured by time to pregnancy (TTP), are unclear.

Objective: To investigate the relationship between preconception plasma phospholipid FA (PPFA) levels and time to human chorionic gonadotropin-pregnancy among women with prior pregnancy loss.

Design, Setting, And Participants: Prospective cohort of 1228 women attempting pregnancy (aged 18 to 40 years, with one or two prior pregnancy losses) followed for up to six cycles at four US university medical centers during 2006 to 2012. PPFA levels were measured at baseline.

Main Outcome Measures: Associations with fecundability overall and by body mass index (BMI) group after adjusting for confounders were estimated using fecundability odds ratios (FORs) and 95% CIs. False discovery rate (FDR) was used to account for multiple comparisons.

Results: Monounsaturated fatty acids (MUFAs) were associated with increased fecundability or shorter TTP [FOR, 1.08 (95% CI, 1.01 to 1.16) per unit increase in percentage of total FAs], whereas polyunsaturated fatty acids (PUFAs) were associated with decreased fecundability or longer TTP [FOR, 0.95 (95% CI, 0.91 to 1.00) per 1% change], though associations only remained significant after FDR adjustment among women with BMI <25 kg/m2. Saturated FA and trans FA were not associated with fecundability. Omega-3 FAs and omega-6 linoleic acid were not associated with fecundability.

Conclusion: We observed associations between preconception MUFA and PUFA levels and fecundability among women with normal BMI, highlighting the importance of FA composition among normal-weight women with prior pregnancy loss.