5 Health Factors That May Affect Fertility

Unhealthy lifestyle habits, such as smoking and an unbalanced diet, can lead to infertility issues in both women and men.


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What does being in peak physical and mental condition have to do with conceiving? According to Dr. Jorge Chavarro, a Harvard researcher and co-author of The Fertility Diet (2009), if you want to be in the “fertility zone”, you need to aim for a healthy lifestyle. Combining five or more of lifestyle factors, such as weight control, physical activity and diet meant a 66 per cent lower risk of infertility due to ovulation problems and a 27 per cent lower risk of infertility due to other causes according to Chavarro and colleagues’ findings published in the journal Obstetrics and Gynecology.

Here are some lifestyle factors you and your partner—he doesn’t get off the hook—can change to up your chances of having a baby:

1. Smoking Increases Infertility in Women and Men

You may see couples in movies enjoying a smoke after lovemaking, but if you’re trying to conceive, butt out. Infertility is higher among smokers compared to non-smokers. Smokers even go through menopause about two years earlier than non-smokers, so your window of opportunity for getting pregnant is smaller.

“Cigarettes contain over 2000 toxins; basically cigarettes poison eggs,” says Ed Hughes, a professor of obstetrics and gynecology at McMaster University, Hamilton, Ont. Smoking reduces the ability of ovaries to produce estrogen, makes eggs prone to genetic abnormalities, as well as raising the risk of miscarriage and ectopic pregnancy. Smoking adversely affects men’s fertility too. Male smokers have a lower sperm count and motility (how well sperm move) and increased abnormalities in sperm shape and function, according to the American Society for Reproductive Medicine.

Luckily, just like quitting can reverse damage to heart and arteries, it can improve your fertility and the effectiveness of fertility treatments. Couples who quit two months before attempting IVF had much better results. Oh, and it’s also cheaper to quit—smokers need twice as many IVF treatments as non-smokers.

2. Obesity Reduces Fertility Treatment Success

While we often hear about the dangers of obesity with regards to heart health and cancer risk, now we know that extra pounds can adversely affect fertility too. “Obesity is linked to an increased risk of irregular periods, miscarriage and decreased success with fertility treatments,” says Hughes. What does weight have to do with conception? “Obesity increases insulin, which decreases the efficiency of glucose metabolism. The pancreas has to work harder to pump out more insulin, which also produces more androgens—and that impedes ovulation,” says Hughes.

The good news is that weight loss of five to 10 per cent can really improve ovulation and pregnancy. “Several studies have found that women who are overweight or obese and lose a modest amount of weight improve their ovulatory function,” says Chavarro. “There are many changes associated with weight loss and relevant to fertility, such as improved insulin sensitivity, which in turn improves the levels of many reproductive hormones, and decreased levels of inflammatory markers.”

Newer findings suggest that male weight matters too. “If men who are overweight or obese, couples have a harder time conceiving regardless of a woman’s weight,” says Chavarro. Lower sperm quality and count has also been observed in studies. Men who are obese (BMI 30-39.9) have 10 per cent lower sperm counts and men who are extremely obese (BMI 40 plus) had sperm counts 25-30 per cent lower than normal weight men (BMI 18.5-24.9). “Sperm are also DNA carriers, and what we find is that obese men have more damage to the sperm DNA,” says Chavarro.

3. How to Calculate Your BMI: Assess Your BMI

But wait—being too thin (e.g. BMI 18) can also impede fertility. “The body is programmed to not procreate if underweight or body is being highly stressed,” explains Hughes. The ideal weight range, according to Chavarro’s research, is a BMI of 20-24.

4. Trans Fats Also Hurt Fertility Chances

Need another reason to drop that bag of chips? There’s only one way for trans fats to get into our bodies, and that’s by consuming them in our diet. Each 2 per cent increase in energy intake from trans fats meant a 73 per cent greater risk of ovulation-related infertility, according to a study in the American Journal of Clinical Nutrition. The latest findings suggest that trans fats also impede male fertility. “It affects the fatty acid composition of sperm and leads to a decreased sperm count,” says Chavarro.

5. Stress Causes Fertility Irregularities

While there’s no direct link between stress and infertility, many women and experts alike do believe that it can contribute to difficulties. Even when you’re not trying to get pregnant, an acute bout of stress like a break-up or moving can cause your period to be late.

High levels of stress may be a culprit in lower sperm production in men and irregular egg production in women. The good news is that reducing stress may help fertility. The most well-known evidence of this comes from a study by Harvard researcher Alice Domar, Ph.D., whose findings showed women who participated in 10-week mind-body program that included relaxation and yoga, were almost three times more likely to get pregnant than women who didn’t. Of 184 infertile women who had been trying to get pregnant for one to two years, 55 per cent who were in the group using yoga and other stress-reducing techniques got pregnant within a year, compared to only 20 per cent of the women in the control group.

From health factors that can affect fertility to drugs that increase fertility, we have much more information on conception in our Ultimate Fertility Guide.

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