Dietary patterns and difficulty conceiving: a nested case-control study.

OBJECTIVE To investigate potential associations between dietary patterns (defined using factor analysis) and difficulty conceiving. DESIGN Case-control study nested in a Spanish cohort of university graduates (Seguimiento Universidad de Navarra [SUN] Project). SETTING Female university graduates all over Spain participating in the SUN Project. PATIENT(S) A total of 485 women, aged 20-45 years, reporting having presented with difficulty getting pregnant, and 1,669 age-matched controls who had at least one child. INTERVENTION(S) None. MAIN OUTCOME MEASURE(S) Reported difficulty getting pregnant. Data were collected from baseline and follow-up questionnaires of the SUN Project. RESULT(S) Two dietary patterns were identified. They were labeled as "Mediterranean-type" and "Western-type" patterns. A lower risk of difficulty getting pregnant was apparent in the highest quartile of adherence to the Mediterranean-type pattern compared with the lowest quartile (odds ratio 0.56, 95% confidence interval 0.35-0.95). Greater adherence to the Western-type dietary pattern showed no association with this outcome. CONCLUSION(S) A greater adherence to the Mediterranean-type dietary pattern may enhance fertility. Further evidence about the relationship between this dietary pattern and fertility is needed to develop nutritional interventions for women desiring to get pregnant.