Preconception dietary patterns in association with live birth and pregnancy loss: a couples-based approach

OBJECTIVE: To examine associations of traditional healthy and fertility-focused preconception dietary patterns in female and male partners, individually and combined, with clinical fertility outcomes. DESIGN: Prospective cohort study. SUBJECTS: Heterosexual couples planning infertility treatment at four United States reproductive endocrinology and infertility care centers, June 2013-April 2019. EXPOSURE: Four a priori dietary patterns: two traditional healthy patterns (Healthy Eating Index-2015 and Mediterranean Diet) and two fertility-focused patterns (Fertility Diet and Pro-fertility Diet). Preconception dietary intake of each partner was assessed by a validated food frequency questionnaire. Each partner's score was calculated for all four patterns; a combined score for each pattern was the sum of the partners' individual scores. MAIN OUTCOME MEASURES: Live birth and pregnancy loss before 20 weeks' gestation. Log-binomial models estimated crude and adjusted risk ratios per SD increase in dietary pattern score of female partners, male partners, and couples combined. RESULTS: Of 2,370 couples, 1,054 experienced a pregnancy, 287 a pregnancy loss, and 821 a live birth. Greater alignment of reported dietary intake with traditional healthy patterns, as reflected by increases in Healthy Eating Index-2015 (females, adjusted risk ratio = 1.06 [95% confidence interval, 1.00-1.13]; males, 1.05 [0.99-1.11]; combined, 1.05 [ 0.99-1.12]) and Mediterranean Diet scores (females, 1.05 [0.99-1.12]; males, 1.05 [0.99-1.11]; combined, 1.06 [1.00-1.12]), by females, males, or couples combined was associated with a higher likelihood of live birth. For female partners only, alignment of reported dietary intake with a Fertility Diet showed a similar association (1.05 [0.99-1.12]). Alignment of reported intake with a Pro-fertility Diet was not associated with live birth. None of the dietary patterns was associated with pregnancy loss. CONCLUSION: Among couples experiencing infertility, following established, broadly recommended dietary patterns known to improve overall health also may offer modest benefits for fertility. In contrast, fertility-focused patterns may offer little or no fertility benefits and likely are more difficult to follow than traditional healthy dietary patterns.