Female dietary antioxidant intake and time to pregnancy among couples treated for unexplained infertility

Abstract

Objective: To determine whether increased antioxidant intake in women is associated with shorter time to pregnancy (TTP) among a cohort of couples being treated for unexplained infertility.

Design: Secondary data analysis of a randomized controlled trial.

Setting: Academic medical center associated with a private infertility center.

Patients: Females with unexplained infertility.

Interventions: None.

Main outcome measure(s): The time it took to establish a pregnancy that led to a live birth.

Result(s): Mean nutrient intake exceeded the estimated average requirement (EAR) for vitamins C and E. No differences in mean intake of any of the antioxidants were noted between women who delivered a live-born infant during the study period vs. those who did not. In multivariable models, intake of β-carotene from dietary supplements was associated with shorter TTP among women with body mass index (BMI) ≥25 kg/m(2) (hazard ratio [HR] 1.29, 95% confidence interval [CI] 1.09-1.53) and women <35 y (HR 1.19, 95% CI 1.01-1.41). Intake of vitamin C from dietary supplements was associated with shorter TTP among women with BMI <25 kg/m(2) (HR 1.09, 95% CI 1.03-1.15) and women <35 y (HR 1.10, 95% CI 1.02-1.18). Intake of vitamin E from dietary supplements among women ≥35 y also was associated with shorter TTP (HR 1.07, 95% CI 1.01-1.13).

Conclusion(s): Shorter TTP was observed among women with BMI <25 kg/m(2) with increasing vitamin C, women with BMI ≥25 kg/m(2) with increasing β-carotene, women <35 y with increasing β-carotene and vitamin C, and women ≥35 y with increasing vitamin E.

Clinical trial registration number: NCT00260091.

Keywords: Diet; antioxidants; nutritional epidemiology; oxidative stress; unexplained infertility.