Tips for avoiding infertility

Within a year of trying, 92 percent of healthy couples will find themselves pregnant. The remainder, however, face the possibility that they will never become pregnant without medical help for one or both partners. Don't automatically blame the female half of the couple; the cause of infertility is just as likely to lie with men as with women. Our advice for reducing the risk of infertility includes options for both of you.

The odds of getting pregnant plummet with age. In men, the drop usually begins in the early forties thanks to sperm that, like men themselves, tend to move slower with age.

Women are most fertile between 19 and 26, when they have a one-in-two chance of getting pregnant if they have sex when they're most fertile (typically, two days after ovulating). A woman aged 35 to 39 has only about a one-third chance of getting pregnant during that time, and less if her partner is at least five years older.

In women, obesity plays havoc with reproductive hormones, more than doubling the risk of infertility and increasing by tenfold the likelihood that it will take longer than usual to get pregnant. In men, a nine kilogram (20 pound) weight gain increases the risk of infertility by about 10 percent.

If you decide to lose weight by dieting, consider a high-protein, low-carbohydrate approach, which several studies suggest works best to return reproductive hormones to normal levels.

Men, did you ever consider that your smoking habit lessens your chances of getting your partner pregnant? It does. Smoking creates free radicals, molecules that damage healthy cells. Having too many free radicals, also triggered by a poor diet, affects how many sperm you make and how fast they swim.

It's not clear whether stress contributes to infertility or vice versa, but studies find that infertile women who seek help from assisted reproductive techniques like in vitro fertilization (IVF) have much higher levels of stress hormones than women who aren't infertile.

Studies also find higher levels of stress hormones in women with disturbances in their menstrual cycles that could affect fertility, such as endometriosis. One study also found lower rates of pregnancy associated with higher stress levels in couples undergoing IVF.

Women trying to become pregnant shouldn't wait until they conceive to cut back on drinking. One study of healthy women who were not alcoholics found that those who imbibed more than three drinks a day had disrupted menstrual cycles and temporary infertility

Studies find improved fertility in men and women who take vitamin C supplements. In men, supplementing daily with 200 to 1,000 milligrams of C increases sperm production.

Buy a vitamin C supplement that contains flavonoids; the two together work better than either alone to reduce oxidative damage to sperm. In women, the dose required to boost fertility was 750 milligrams a day. Don't take more than 500 milligrams at once, however; your body can't absorb more than that.

Women who are sexually active but aren't in committed relationships should be screened at least annually for sexually transmitted infections (STIs). They can cause pelvic inflammatory disease, in which bacteria move up through the cervix into the uterus and fallopian tubes, creating scarring that can prevent a normal pregnancy. In addition to STIs, men should be checked regularly for inflammation of the prostate gland. All can damage sperm.