Long-chain omega-3 fatty acids and their food sources have garnered interest as a potential nutrient with wide-range health benefits, including fertility.

This study aimed to investigate the association of women’s and men’s intake of omega-3 fatty acids and omega-3 rich–foods with semen quality and outcomes of infertility treatment with assisted reproductive technologies.

Couples presenting to the Massachusetts General Hospital were invited to enroll in a prospective cohort study (2007–2020). Male and female diets were assessed using a validated 131-item food frequency questionnaire. The primary outcomes were implantation, clinical pregnancy, and live birth probabilities. The secondary outcomes included total and clinical pregnancy loss and conventional semen parameters, for males only. We estimated the relationship between intakes of omega-3 fatty acids, nuts, and fish and the probability (95% confidence interval) of study outcomes using generalized linear mixed models to account for repeated treatment cycles per participant while simultaneously adjusting for age, body mass index, smoking status, education, dietary patterns, total energy intake, and male partner diet.

A total of 229 couples and 410 assisted reproductive technology cycles were analyzed for primary and secondary outcomes. Of note, 343 men contributing 896 semen samples were included in analyses for semen quality measures. Women’s docosahexaenoic acid + eicosapentaenoic acid intake was positively associated with live birth. The multivariable-adjusted probabilities of live birth for women in the bottom and top quartiles of eicosapentaenoic acid + docosahexaenoic acid intake were 0.36 (95% confidence interval, 0.26–0.48) and 0.54 (95% confidence interval, 0.42–0.66) (P trend=.02). Eicosapentaenoic acid + docosahexaenoic acid intake was inversely related to the risk of pregnancy loss, which was 0.53 among women in the lowest quartile of eicosapentaenoic acid + docosahexaenoic acid intake and 0.05 among women in the highest quartile (P trend=.01). Men’s intake of total omega-3 fatty acids was positively related to sperm count, concentration, and motility, but unrelated to any assisted reproductive technology outcomes. Similar associations were observed when evaluating the intake of primary food sources of these fatty acids.

Women’s consumption of omega-3 fatty acids and omega-3–rich foods may improve the probability of conception by decreasing the risk of pregnancy loss. In addition, men’s intake of omega-3 fatty acids may influence semen quality.