Grieger JA, et al. - Experts scrutinized the connection between preconception dietary intake with reduced fecundity as measured by a longer time to pregnancy (TTP). Findings demonstrated that lower intake of fruit and higher intake of fast food in the preconception period were both related to a longer TTP. The significance of considering preconception diet for fecundity outcomes and preconception guidance was highlighted.

Methods

• This multi-center pregnancy-based cohort study examined 5,628 nulliparous women with low-risk singleton pregnancies who participated in the Screening for Pregnancy Endpoints (SCOPE) study.
• A total of 5598 women were included for this trial.
• During the first antenatal study visit (14–16 weeks’ gestation), data was extracted on retrospectively reported TTP and preconception dietary intake.
• Dietary information for the 1 month prior to conception was obtained from food frequency questions for fruit, green leafy vegetables, fish and fast foods, by a research midwife.
• This study included the documentation of the use of any fertility treatments associated with the current pregnancy (yes, n = 340, no, n = 5258).
• Accelerated failure time models with log normal distribution assisted in measuring the time ratios (TR) and 95% CIs.
• A comparison was carried out of the impact of differences in dietary intake on infertility (TTP >12 months) via a generalized linear model (Poisson distribution) with robust variance estimates, with resulting relative risks (RR) and 95% CIs.
• All analyses were controlled for a range of maternal and paternal confounders.
• Sensitivity analyses appeared to aid in evaluating the potential biases that were common to TTP studies.

Results

• Data shed light on the connection between lower intakes of fruit and higher intakes of fast food with modest increases in TTP and infertility.
• As per the outcomes, absolute differences between the lowest and highest categories of intake for fruit and fast food were in the order of 0.6-0.9 months for TTP and 4-8% for infertility.
• In contrast with women who consumed fruit ≥3 times/day, the adjusted effects of consuming fruit ≥1-<3 times/day (TR = 1.06, 95% CI: 0.97-1.15), 1-6 times/week (TR = 1.11, 95% CI: 1.01-1.22) or <1-3 times/month (TR = 1.19, 95% CI: 1.03-1.36), corresponded to 6, 11 and 19% increases in the median TTP (P_trend=0.007).
• Compared with women who consumed fast food ≥4 times/week, the adjusted effects of consuming fast food ≥2-<4 times/week (TR = 0.89, 95% CI: 0.81-0.98), >0-<2 times/week (TR 0.79, 95% CI 0.69-0.89) or no fast food (TR = 0.76, 95% CI: 0.61-0.95), corresponded to an 11, 21 and 24% reduction in the median TTP (P_trend < 0.001).
• With regard to infertility, compared with women who consumed fruit ≥3 times/day, the adjusted effects of consuming fruit ≥1-<3 times/day, 1-6 times/week or <1-3 times/month appeared to correspond to a 7, 18 and 29% increase in risk of infertility (P_trend=0.043).
• Likewise, in contrast with women who consumed fast food ≥4 times/week, it was determined that the adjusted effects of consuming fast food ≥2-<4 times/week, >0-<2 times/week, or no fast food, corresponded to an 18, 34 and 41% reduced risk of infertility (P_trend < 0.001).
• No link was demonstrated between pre-pregnancy intake of green leafy vegetables or fish with TTP or infertility.
• Stability was reported in the estimates across a range of sensitivity analyses.