Alcohol and caffeine
The damaging effects of alcohol on the fetus during pregnancy are legion – abnormal facial features, microcephaly, low birth weight, hyperactive behavior, vision or hearing deficits, speech and language delays, and intellectual disability. Less known is the amount of alcohol that may have an effect during preconception. One of the first reports on the effect of alcohol on IVF concluded: a 13% decrease in the number of eggs aspirated; a 2.86 times increase in risk of not achieving pregnancy; and a 2.21 times increase in risk of miscarriage. For men, one additional drink per day increased the risk of not achieving a live birth from 2.28 to 8.32 times.12 Subsequent studies demonstrate a 16% reduction in IVF pregnancies in women who have at least four drinks per week; when the couple drank at least four drinks per week, the pregnancy rate decreased by 21%.13
However, a study from Denmark did not demonstrate a negative effect of low to moderate pretreatment amounts of alcohol and caffeine on IVF outcomes.14 Nevertheless, there is evidence that reducing or abstaining from alcohol intake may improve IVF outcomes.15 While there have been reports of higher miscarriage rates from caffeine,16,17 not all reports support a negative association.18
Smoking
The use of tobacco has been estimated to contribute to 13% of female infertility in a dose-response manner, including secondhand smoke. During ART, smoking reduces ovarian response to gonadotropins and decreases IVF success by up to 50%. Discontinuing smoking for 6 months beforehand appears to restore normal outcomes.19-20
The American Society for Reproductive Medicine Practice Committee on smoking provides the following invaluable information to share with patients on the harmful reproductive effects of smoking:21
- Early menopause by accelerating the loss of eggs.
- Higher rates of miscarriage and ectopic pregnancy.
- A decrease in sperm function.
- Possible genetic damage to eggs and sperm.
- Reduced sperm in son from maternal smoking.
Weight and exercise
Compared with normal-weight women, those with obesity are three times more likely to have ovulatory dysfunction;22 a lower chance for conception;23 and infertility.24 Obese women have higher rates of miscarriage and recurrent miscarriage, reduced success with ART, an increased number of canceled cycles, and poorer quality oocytes retrieved. During pregnancy, obese women have three to four times higher rates of gestational diabetes and preeclampsia,25 as well as likelihood of having a fetus with macrosomia and birth defects, and a 1.3-2.1 times higher risk of stillbirth.26
Regarding physical activity, the rate of pregnancies (39.0% vs. 16.0%, P = .002) and live births (24.4% vs. 7.4% (P = .004) were higher with regular exercise vs. being sedentary. Obese women who exercised regularly had a live birth rate over threefold higher compared with those who were not active.27 Moderation should be employed given that women who exercise to exhaustion have 2.3 times the odds of fertility problems.28 In men, obesity has been shown to increase estrogens and reduce spermatogenesis. Exercise has improved semen parameters and testosterone. Paternal physical and sedentary activities were not related to clinical pregnancy or live birth rates following infertility treatment.29 As in women, men experience negative effects from high-intensity exercise, including bicycling, which can result in decreased semen parameters, follicle-stimulating hormone, LH, and testosterone levels.30
In couples desiring a more natural approach to infertility, fertility specialists can address environmental and lifestyle factors that may improve reproduction. When natural attempts at conception are not applicable or successful, IUI and ART are appropriate treatment options after considering estimated success rates as well as the physical, emotional, and financial investment of patients.
Dr. Trolice is director of The IVF Center in Winter Park, Fla., and professor of obstetrics and gynecology at the University of Central Florida, Orlando.
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