the Impact of Weight on Fertility
Weight can often be a sensitive topic, but it’s important to address, not only because the rate of obesity is increasing but also because it can have a significant impact on your overall health and your ability to get pregnant—whether you're undergoing fertility treatment or not.
What is considered a healthy weight?
A person can determine if he or she is maintaining a healthy weight by using a body mass index (BMI) score. BMI measures the percentage of body fat based on your height and weight. A normal (or “ideal”) BMI falls between 19 and 25.
How does weight impact female fertility?
Studies that have compared overweight and obese women with women of normal weight who are using assisted reproductive technology (ART) treatments have shown excess weight having negative effects such as:
- Lower pregnancy rates
- Increased miscarriage rate
- Lower rate of a live birth
In addition, because BMI is strongly connected to treatment success, obese women who are undergoing ART may:
- Need higher and longer doses of ovarian stimulation medication
- Have fewer or more immature eggs to retrieve or more cancelled cycles due to an inadequate response
- Experience higher risk of bleeding, damage to surrounding organs, and an anesthesia-related complication during surgery or egg retrieval
- Gestational diabetes
- High blood pressure
- Cesarean section (also known as a C section)
- Birth defects
Women who are underweight may not be getting adequate nutrition or may have hypothalamic amenorrhea that keeps them from ovulating on a predictable basis as well. Studies have shown though that in patients whose infertility is specifically due to weight, correction of the underlying disorder can lead to pregnancy in up to 70 percent of women.
How does weight impact male fertility?
Just like with women who have fertility complications related to BMI, men can experience similar difficulties. If men are overweight, it can affect sperm count and sperm motility (movement). When the male hormones are increased (a result of a higher BMI at a heavier weight), it can impair the man’s ability to make sperm on a regular basis. The natural balance of testosterone and estrogen can be affected, which then may affect the ability to produce sperm. Men who are obese can also experience warming of the scrotum. If the scrotal temperature increases by 1 or 2 percent, it can impact sperm production or survival.
Weight Loss Improves Health and Outcomes
The good news is, a modest weight loss of 5 to 10 percent can affect a woman’s ability to resume regular ovulation if her inability to conceive is associated with weight alone.
If men are able to achieve a healthier BMI, that, too, can greatly improve their sperm production. Men produce millions of new sperm every day, making it highly beneficial to men who want to alter their lifestyle habits. Sperm takes about 72 days to mature, which means that men who lose weight or make positive lifestyle changes only need to wait about 3 months before seeing improvements in sperm quality—and an increase in their chances of reproductive success.
Exercise and Fertility
Many patients ask how much exercise is ok when they're trying to get pregnant. While the link between exercise and fertility is a difficult to define with certainty, some facts have been well established.
- Intense physical activity, such as that of competitive female athletes, can disturb the menstrual cycle, but moderate activity has little effect on the cycle.
- Obesity is associated with decreased fertility. Weight loss in obese women can improve their fertility. Weight loss can also improve menstrual regularity in obese women with polycystic ovary syndrome (PCOS).
Improve Your Chances of Conception
At Shady Grove Fertility, we always recommend and encourage overweight and obese patients to move towards the normal weight range based on their height through healthy diet and exercise. We focus on structured weight loss programs that include behavioral modification, in addition to regular exercise with a minimum of 30 minutes of moderate activity at least 3 days per week (always check with your physician before beginning any type of exercise regimen).
Patients and physicians can work together to non-invasively help a woman or man reach an optimal weight for conception. Being aware of the importance of body weight on reproduction can enable couples to maintain their ideal body weight before they begin fertility treatment. When patients have their weight at the ideal level, it can greatly increase their chances of reproductive success and reduce potential risks and complications.