There is a strong correlation between food intolerance/ food allergies and killer cells. An overactive immune system is more likely to attack an embryo. In the article Treatment for recurrent miscarriages, I discuss how intralipid therapy can suppress killer cells. Another way to suppress the cells, is to avoid foods your body is intolerant of. Unfortunately, most people are unaware if they have a mild intolerance. The two worst offending foods are gluten and dairy. An igG immunoglobulin test can reveal if these allergies are present.
There is also a link between dairy and anovulation. Anneli Rufus's article, Can Food Make You Infertile? discusses a Harvard-affiliated study which revealed that "women who eat lots of low-fat dairy products face an 85 percent higher risk of ovulatory infertility than women who consume little or no low-fat dairy products". Researchers hypothesize that the hormones in cow's milk: prolactin, somatostatin, melatonin, oxytocin, growth hormone, lutenizing releasing hormone, thyroid stimulating hormone, estrogens, progesterone, insulin, corticosteroids, are causing hormonal disruptions in women's bodies. If you are dealing with unexplained infertility, giving up dairy may be a worthy endeavor.