This can be a broad subject especially since there is an endless amount of information out there floating around in the abyss of the interwebs. But how do you weed through the information jungle separating the good from the bad? Start here. Jackie Gutmann, MD offers her thoughts on some common factors where there is scientific data that supports (or refutes) lifestyle modifications that impact fertility. Spoiler alert, the key as cliché as it may sound, begins with moderation.

What factors can impact my fertility?

Body Weight

Boosting Your Fertility ImageObesity is associated with infertility and a lower pregnancy rate in women undergoing in vitro fertilization (IVF). Women with a very low body mass index (BMI) also are more likely to experience infertility and have a lower likelihood of success with IVF than women whose BMI falls in the normal range. In men, obesity is also associated with infertility — sperm count and motility have been shown to be lower in obese men. Weight loss has been shown to improve semen parameters. Erectile dysfunction is more common in obese men. There is no scientific data that supports one diet over another with respect to maximizing fertility.

Exercise

Some data that suggest that moderate exercise, regardless of BMI, is associated with the highest pregnancy rates in women. Daily exercise, however, has been shown to be associated with reduced fertility—especially if the excessive exercise results in menstrual irregularity. Exercise has a similar effect on men—one hour of exercise three times weekly seems to be associated with a higher count, motility, and normal appearing sperm than sperm from men who do not exercise and those who engaged in more frequent/vigorous exercise

Caffeine Intake

Excessive caffeine intake (>500 mg/day) appears to be associated with a delay in time to conception. Consumption of moderate amounts of caffeine (200-300 mg/day) has been associated with lower pregnancy rates and higher rates of miscarriage. In one study, pregnancy rates with IVF were reduced in women consuming greater than 50 mg of caffeine daily. There is little data on the impact of caffeine on male fertility. The average 8oz cup of coffee has approximately 100 mg of caffeine, but not all coffees are created equal—look up the caffeine content of your favorite caffeinated beverage.

Alcohol Consumption

Extreme alcohol intake has been associated with decreased fertility. What is less clear is the amount of alcohol it takes to negatively impact reproductive function. A review of the literature suggested that four drinks per week is associated with a decreased likelihood of successful IVF in women. Heavy alcohol consumption in men is associated with decreased sperm count, motility, and percent of normal appearing sperm. Some studies have shown a negative impact on sperm with more moderate drinking. Semen parameters have been shown to improve after three months of abstinence from alcohol.

Smoking

There is strong evidence that nicotine negatively effects fertility. It has been suggested that women who smoke add ten years to their reproductive ages—a 30 year old smoker has the reproductive potential of a 40 year old! Smoking in men negatively impacts sperm quantity and quality and is associated with reduced success with IVF and intra-cytoplasmic sperm injection (ICSI). There is little scientific data on the impact of electronic cigarettes on fertility, but they contain nicotine, so they are likely associated with a decrease in fertility. Ideally, nicotine patches and gum should be avoided.

Recreational Drugs

Studies on the impact of recreational drugs on female fertility are few. Women who use marijuana appear to be more likely to experience infertility. In men, marijuana has been found to increase ejaculation problems and impotence as well as reduce sperm count and motility. Most negative effects from recreational drugs have been shown to be reversed by discontinuing their use.

Cell Phones

In some animal studies evaluating the effect of the radio-frequency electromagnetic radiation (RF-EMR) of cell phones on reproductive function, a negative impact on the ovaries, uterus, and embryo has been identified. Sperm exposed to RF-EMF have decreased motility and are more likely to have an abnormal appearance. The use of cell phones may decrease sperm concentration and motility as well as normal appearance. The abnormalities seemed to be directly related to the amount of use. However, there is no evidence that use of cell phones by women or men is associated with infertility.

And if that were not enough…

In some studies, tight clothing in men has been shown to increase scrotal temperature raising concern that it may impair sperm production. At present, there is no evidence that tight clothing is associated with infertility. Similarly, it does not appear that hot baths or hot tubs are associated with male infertility.

We know that some lifestyle factors affect fertility. Others you may have heard about are not supported by scientific data. In general, the “Goldilocks” approach is best — not too little, not too much, but just right. If you every have questions, ask your doctor.

Jackie Gutmann, MD, is Clinical Associate Professor of Obstetrics and Gynecology at Thomas Jefferson University and a partner at RMA of Philadelphia.