Article contributed by:
Desireé McCarthy-Keith, MD
Georgia Reproductive Specialists, a participating provider in the WINFertility Network
Couples and individuals who are planning a pregnancy often ask, “What can we do to improve our chances of getting pregnant?” Although some aspects of your personal or medical history cannot be modified, adjustment of certain lifestyle behaviors can improve your fertility. The greatest non-modifiable factor affecting fertility is the age of the female partner. Awareness of the significant impact of aging on fertility potential allows couples to pursue fertility evaluations and treatments sooner.
Identification of modifiable lifestyle factors allows couples to adjust behaviors which may be harmful to their fertility potential. Throughout the reproductive years, there is a gradual and permanent loss of eggs from the ovaries. This process is accelerated after the mid-thirties. The loss of eggs is compounded by a decrease in the quality of the remaining eggs over time. This results in a lower chance of pregnancy and a greater chance of miscarriage if pregnancy does occur. When planning for a family, women should understand that delaying childbearing can decrease chances for pregnancy and that infertility evaluation should be sought sooner as they gets older. It is recommended that couples and individuals seek care after six
months of infertility once the female partner reaches age 35 or older. Fertility factors such as anovulation, tubal infertility or male factor infertility may warrant earlier evaluation and treatment, regardless of age. Unlike egg production in women, sperm production in men continues with advancing age. Although sperm production continues, some studies have found that sperm quality and fertility decrease in men over 40 years old.
BMI and Fertility
Maintaining a healthy weight is important for general wellness, and having a weight outside of the healthy range can be harmful to your fertility. Both underweight and overweight women are at risk of decreased fertility. The usual way to determine if your weight falls within the “healthy” range is by calculation of your body mass index (BMI). Your BMI is calculated from your weight in kilograms (kg) divided by your height in meters squared (m2). Tables highlighting the ranges for underweight, normal
weight and overweight categories in men and women are readily available and easy to interpret [Table].
Variations do exist by race, but in general a BMI between 19 and 25 kg/m2 is considered normal for women. Overweight is defined as a BMI between 25 and 29.9 kg/m2 and obesity is defined as a BMI greater than 30 kg/m2. Women with low BMI (<17 kg/m2) and high BMI (>27 kg/m2) are less likely to ovulate regularly, which can lead to infertility. In overweight and obese women, anovulatory infertility is due to high insulin levels related to insulin resistance. Excess insulin can lead to high male hormone (androgen) levels, and these excess androgens can alter the normal ovarian function and ovulation. The
anovulation that occurs in infertile women with low BMI is often associated with excessive exercise or low calorie intake. These behaviors can suppress reproductive hormone production, which results in a lack of regular ovulation.
Less is known about the impact of weight on male fertility. There is evidence that men with increased BMI have lower reproductive hormone levels, but the effect of these lower hormone levels on sperm count and function is unclear. Some studies have found lower sperm counts in men with increased BMI, where others have found no difference compared to men with normal BMI. Weight management is critical to improving fertility in women with both high and low BMI. A weight loss of 5% to 10% can improve ovulation and pregnancy rates in infertile women who are overweight. For infertile women with low BMI, weight gain can improve the frequency of ovulation and the chance for pregnancy. Weight loss in men can improve hormone levels, but the effect of weight loss on fertility is not known. Reaching and maintaining a healthy weight is best achieved through a combination of dietary modification and moderate exercise for both male and female partners.
Exercise and Fertility
Regular physical activity is the cornerstone to achieving and maintaining a healthy weight. As mentioned, excessive exercise in women can lead to anovulatory infertility, but even ovulatory women’s fertility can be negatively impacted by too much exercise. This negative impact may be due to low progesterone levels in the second half of the menstrual cycle or to alteration in reproductive hormones related to ovulation. The hormone leptin has recently been identified as a possible contributor to infertility in women who exercise excessively. Leptin plays a key role in energy balance and strenuous exercise can reduce leptin levels. Low leptin levels are associated with reproductive hormone imbalance, which may cause infertility. Population studies have found that women who engage in more than 7 hours per week of intense aerobic activity have a higher incidence of ovulatory infertility. In women undergoing in vitro fertilization (IVF) procedures, participation in four or more hours of intense exercise per week has been associated with lower treatment success. In general, excessive exercise in males does not appear to affect fertility; although certain types of exercise (e.g. cycling and triathlon) have been associated with alterations in sperm quality.
Tobacco use and Fertility
Tobacco use is associated with decreased fertility in women and altered sperm quality in men. Most studies indicate that smoking more than 10 cigarettes per day decreases the likelihood of pregnancy. This is true for women trying to get pregnant on their own as well as for women undergoing IVF. It is believed that toxins in cigarette smoke cause damage to ovarian follicles, accelerate depletion of eggs in the ovary and lead to premature aging of the ovary by one to four years. Cigarette smoking has also been associated with increased miscarriages and ectopic pregnancies. Studies demonstrate that the negative impact of smoking on fertility can be reversed within one year of quitting.
Alcohol and Fertility
In women, moderate (3-13 drinks per week) and heavy (14 or more drinks per week) alcohol intake are associated with longer time to conception and infertility. Heavy drinking in males is associated with lower reproductive hormone levels and decreased sperm production. Men and women should limit alcohol consumption to moderate use when trying to conceive. Women should abstain from alcohol at conception and throughout pregnancy to avoid the risks of fetal alcohol exposure.
Caffeine and Fertility
Caffeine consumption in America is quite high and excess caffeine intake has been associated with decreased fertility. The most common sources of caffeine are coffee, tea, carbonated sodas and chocolate containing products. By far, coffee contains the highest amounts of caffeine. Heavy caffeine intake is often associated with increased age, tobacco and alcohol use so it is difficult to determine the effect of caffeine use on fertility alone. Most studies suggest that consuming less than 200 to 300 mg of caffeine a day does not harm fertility, but that consuming greater amounts may contribute to infertility and increased miscarriages. The March of Dimes recommends that women who are pregnant or trying to get pregnant limit caffeine consumption to less than 200 mg a day. There is no evidence suggesting that caffeine consumption affects male fertility.
Stress and Fertility
Some studies suggest that stress can cause female infertility and that psychological stress is a risk factor for decreased semen quality in men. Planning for a pregnancy can be stressful and encountering fertility difficulties can increase psychological stress. Relaxation techniques, acupuncture, stress management and group therapy can be useful in reducing stress and may improve fertility.
Factors Affecting Male Fertility
Exposure to infectious diseases and toxins in the workplace and at home can lead to infertility in men. Communicable diseases like mumps and tuberculosis and sexually transmitted infections like gonorrhea and chlamydia can produce an inflammatory condition of the testes called orchitis. Orchitis produces an immune response in the testes and can cause damage to sperm. In some men, this can cause infertility. Chemotherapy drugs and medicines that interfere with male hormone levels can also harm sperm production and testicular function. Exposure to high-doses of radiation is associated with failed sperm production and infertility, as are occupational exposures to pesticides and heavy metals like lead, cadmium and mercury. Prolonged high testicular temperature is also believed to be harmful to sperm production and sperm quality. Frequent use of saunas, hot tubs or hot baths, prolonged sitting during work or driving, wearing tight fitting underwear and prolonged laptop computer use can deliver high heat to the testes and damage sperm. Varicocele is a medical condition where dilated veins in the scrotum maintain high heat in the testis and cause damage to sperm.
Men and women should be aware of the age-related impact on male and female fertility. Engaging in unhealthy lifestyle behaviors can make it more difficult to get pregnant and modifying these behaviors can improve your fertility. Achieving a healthy weight with proper nutrition and exercise can restore ovulation and improve chances of pregnancy in women with low and high BMI. Women should limit excessive physical activity to less than seven hours per week and men should be aware that certain types of exercise are associated with altered sperm quality. Cigarette smoking should be avoided based on long-term health effects as well as its impact on male and female infertility. Alcohol and caffeine consumption should also be limited in women trying to get pregnant and alcohol use should be avoided during pregnancy altogether. Men should avoid environmental and occupational exposures which can be harmful to sperm production and sperm quality. When planning for pregnancy, adopting these healthy lifestyle behaviors can improve your fertility potential and reduce the time to achieve a pregnancy.