The Association between Seafood Intake and Fecundability: Analysis from Two Prospective Studies

Background: Seafood is an important source of omega-3 fatty acids, which have been associated with improved oocyte quality and embryo morphology in some studies. However, seafood is also a source of persistent organic pollutants and heavy metals, which may adversely affect fecundity. Previous studies of seafood intake and fecundity have generated inconsistent results. Methods: In two prospective cohort studies of 7836 female pregnancy planners from Denmark (Snart Foraeldre,n= 2709) and North America (PRESTO,n= 5127), we evaluated the association of dietary intake of total seafood and marine-sourced long-chain omega-3 fatty acids (eicosapentaenoic acid, docosahexaenoic acid, and docosapentaenoic acid) with fecundability. Participants completed a baseline questionnaire on sociodemographics, behavioral factors, anthropometrics, and medical history, and a food frequency questionnaire. Pregnancy status was updated bimonthly for up to 12 months or until reported conception. We estimated fecundability ratios (FRs) and 95% confidence intervals (CIs) using proportional probabilities regression models, adjusted for energy intake and other potential confounders. We restricted analyses to women with <= 6 menstrual cycles of attempt time at enrollment. Results: Intake of total seafood or marine-sourced long-chain omega-3 fatty acids was not appreciably associated with fecundability in either cohort (>= 200 vs. <50 g/week total seafood: FR = 0.94, 95% CI: 0.79-1.10 in Snart Foraeldre; FR = 1.00, 95% CI: 0.90-1.13 in PRESTO; marine fatty acids: >= 90th vs. <25th percentile: FR = 1.00, 95% CI: 0.85-1.18 in Snart Foraeldre; FR = 0.97, 95% CI: 0.86-1.09 in PRESTO). In PRESTO, where we collected additional data on seafood preparation, we observed an inverse association between fecundability and fried shellfish (>= 10 g/week vs. none: FR = 0.77, 95% CI: 0.61-0.98), but not unfried shellfish (>= 20 g/week vs. none: FR = 0.98, 95% CI: 0.89-1.07); in Snart Foraeldre, there was no association with total shellfish intake. Conclusions: We found little association between seafood intake and fecundability overall, but greater intake of fried shellfish was associated with reduced fecundability among North American participants.