Alcohol
Drinking 1+ drinks per day reduces odds of getting pregnant by 50%
319 women were followed for an average of 8 menstrual cycles, resulting in 124 pregnancies. Alcohol intake was significantly associated with reduced fertility. A dose-response effect was apparent, with those who drink <1 drink/day experiencing a 30% reduction, and those who drink 1+ drinks/day experiencing a 50% reduction in the fertility odds ratio when compared to nondrinkers. Smoking and caffeine were not associated with fertility in this model whether modeled categorically or continuously as cigarettes per day or milligrams of caffeine per day. Including prior cycles at risk as a covariate in the analysis (as opposed to prospectively measured cycles) did not alter the results.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3203540/
Drinking before becoming pregnant lowers live birth rate by up to 21% in IVF patients
In this prospective cohort study, men and women completed a self-administered questionnaire before their first IVF cycle. We conducted multicycle analyses with final models adjusted for potential confounders that included cycle number, cigarette use, body mass index, and age. RESULTS: A total of 2,545 couples contributed 4,729 cycles. Forty-one percent of women and 58% of men drank one to six drinks per week. Women drinking at least four drinks per week had 16% less odds of a live birth rate compared with those who drank fewer than four drinks per week (odds ratio 0.84). For couples in which both partners drank at least four drinks per week, the odds of live birth were 21% lower compared with couples in which both drank fewer than four drinks per week (odds ratio 0.79). CONCLUSION: Consumption of as few as four alcoholic drinks per week is associated with a decrease in IVF live birth rate.
http://www.ncbi.nlm.nih.gov/pubmed/21173655
Consuming one alcoholic drink per day boosts estrogen 20%
After adjustment for covariates, alcohol consumption was moderately associated with higher circulating estrogen levels; those who consumed more than one drink per day had 20% higher estrogen levels than non-drinkers.
Alcohol shortens follicular phase and menstrual cycle
Women who consumed one or more alcoholic drinks per week were significantly less likely to have long cycles (odds ratio = 0.38) or long follicular phases (odds ratio = 0.39).
http://aje.oxfordjournals.org/content/160/2/131.full
Other topics covered under Diet and Miscarriage:
Alcohol, Chocolate, Dairy, Dietary Fat, Eggs, Fiber, Fruit, L-Arginine, Meat, Methionine, Soy, Vegetables
For a concise list of qualities found to affect one's risk of miscarriage, see: Causes of Miscarriage