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Continually updated but major update 5/25/19
Delay of fertility
Couples are delaying their efforts to have a family because of careers and because contraception allows them to wait until their circumstances are more ideal. Unfortunately, fertility decreases with ages of the male (De la Rochebrochard, 2006, Fratterelli, 2008, Girsh, 2008) as well as the female. The antioxidant status of tissues of the body is lower as age increases. The older age at marriage often means contact with more sexual partners and sexually transmitted diseases like chlamydia which can damage the fallopian tubes. Endometriosis increases as more menstrual periods occur. Finally, more time allows more body weight to accumulate. Even an extra 100 calories per day causes a weight gain of 10 pounds per year and 100 pounds in 10 years. Obesity decreases fertility, increases miscarriage, and causes pregnancies to be more complicated (see weight and fertility).
Personal habits such as smoking, alcohol, and even caffeine can have effects on fertility. Surprisingly, even second hand smoke damages the sperm and eggs, apparently as much as smoking.
Exercise and fertility
Modern society has devised so many tools to avoid physical activity that we all have to make a conscious effort to set aside time for exercise. Recent studies show that fertility increases with moderate exercise in both the male and female partner. It makes sense, because exercise improves blood flow and the body's natural antioxidant status. On the other hand, high levels of exercise appear to reduce fertility. Two studies have suggested more than 3-5 hours of vigorous exercise per week for the female partner may reduce fertility (Morris, 2006, Wise, 2012), hence the above guidelines. Moderate or even high exercise for the male will enhance erectile function and will help prevent any decline of that function with aging. However, in a very thorough and well controlled study, normal young men assigned to regular high intensity exercise had significant reductions of most semen parameters and gonadotropin and testosterone levels (Safarinejad, 2009, Hayden RP, 2018). As it is likely that men with decreased semen quality would have similar or greater adverse effects, we do not recomment regular, high intensity exercise for the male partner. Biking for > or = 5 hours per week (Wise, 2011) has been reported to have negative effects on sperm. Overheating of the testicles may explain the effect of biking.
Nutrition and fertility - click on "lifestyle and fertility"
Sexual dysfunction and fertility
Sexual difficulties are much more common with infertility (see sexual dysfunction and infertility). In one study almost a quarter of couples had sexual dysfunction. This is partly due to the same factors that can harm the eggs and sperm- excess body weight, a less than healthful diet, insufficient exercise, insufficient antioxidant intake, smoking, second hand smoke, and excessive alcohol all impair erectile function (see sexual dysfunction and infertility page on this site and "Survival of the Firmest" available for purchase on Amazon/kindle or "itunes"). Certainly the stress of infertility and fertility treatments and having to time relations to the time of ovulation are also factors, but sex doesn't have to be regimented. Having relations every 1-2 days around ovulation is ideal. Just don't let 3 days pass during that crucial time, and if your ovulation test turns positive, be sure to have relations that night or the next morning. Even before IUI, having regular ejaculation increases the success rate and that probably holds for IVF as well. The sperm's DNA remains more intact when sperm spend less time in the collecting system where oxidative stress can damage them. And, as a bonus, having more frequent erections also improves erectile function and will help to prevent erectile dysfunction in the future.
Stress and fertility
Stress is certainly a factor. The level of stress for a woman with infertility has been compared to having a diagnosis of cancer or HIV. Also, some individuals are naturally more reactive to stress. In one study, women scheduled for IVF were tested with stressful visual and auditory stimuli (Facchinetti, 1997). Those who failed to conceive had significantly greater rises of their blood pressure and pulse rate. That study suggested the adverse effect of stress is due to constriction of blood flow to the pelvic organs.