Here is a summary of foods that have been shown to affect one's odds of having a miscarriage:
Chocolate: causes miscarriage risk to drop by 19%. more...
Dairy: causes miscarriage risk to drop by 33%, and improves fertility. Lowers homocysteine and insulin resistance. more...
Milk: causes miscarriage risk to drop by 40%. Also affects hormones. more...
Cheese: causes miscarriage risk to drop by 50%. more...
Butter: causes miscarriage risk to increase by 100%. more...
Oil: increases miscarriage risk by 60%. more...
Eggs: causes miscarriage risk to drop by 30%. more...
Fiber: lowers miscarriage risk in sheep, and improves fertility in humans. Also affects hormones. more...
Fruit: causes miscarriage risk to drop by 46% to 70% in various studies. more...
Fish and Poultry: cause miscarriage risk to drop by 15% to 30% in different studies. more...
Vegetables: causes miscarriage risk to drop by 40% to 50% in two studies. more...
Overeating or undereating increases risk of miscarriage in pigs; overeating lowers progesterone
The present experiment was conducted to evaluate the effects of feeding allowance level on embryonic survival and reproductive hormone secretion in early gestation gilts. Embryonic survival was affected by dietary treatment; total number of viable embryos and embryo survival of group with medium feed allowance (1.2x maintenance) were higher than high (2x maintenance) or low (0.6x maintenance) groups in the early pregnancy. Progesterone levels were the lowest in the high feeding group (2x maintenance). These data demonstrated that feed allowance level after mating has important consequence on embryo survival, embryo development and uterine development, possibly mediated by nutrition level inducing changes in concentrations of reproductive hormones and/or intermediary metabolites in early pregnancy.
http://www.ncbi.nlm.nih.gov/pubmed/18700853
For a concise list of qualities found to affect one's risk of miscarriage, see: Causes of Miscarriage