October 30, 2020
Obesity is a risk factor for many medical conditions—heart disease, sleep disorders, and some cancers—to name just a few. So it’s not completely surprising that obesity is also a risk factor for infertility. What may surprise you is that being underweight can also make it more difficult to become pregnant.
What is a Good Weight for Pregnancy?
One of the easiest ways to determine if you are underweight or overweight is to calculate your body mass index (BMI). The Centers for Disease Control and Prevention offers this BMI calculator.
A BMI between 19 and 24 is considered normal and an optimal range for a healthy pregnancy. Less than 19 is considered underweight. A BMI between 25 and 29 is considered overweight and greater than 30 places you in the category of obese.
Why Being Overweight Impacts Fertility
Obesity can prevent a woman from ovulating and having a monthly period, making it very unlikely for her conceive.
Ovulation isn't the only issue, however. Even obese women with normal menstrual cycles have lower pregnancy rates than normal-weight women. Other disorders related to obesity—like thyroid disease, insulin resistance, and diabetes—can also affect your ability to conceive.
Why Being Underweight Impacts Fertility
Being underweight may also cause ovulatory dysfunction. Women who exercise excessively and/or have low caloric intake may have irregular or no periods at all, again making it very difficult to conceive. However, the mechanism behind this does differ from that in obese women.
Plan Ahead for Pregnancy Success
If you are considering pregnancy and are facing challenges with being underweight or overweight, your doctor can help you address any underlying medical conditions and offer weight management guidance. He or she may also recommend you see a fertility specialist to help you find the best path forward.
Men Play a Role Too
There is also a connection between fertility and obesity in men. Being overweight may be associated with changes in testosterone levels and other hormones important for reproduction. Low sperm counts and low sperm motility (movement) have been found more often in overweight and obese men than in normal-weight men.
The bottom line: Achieving a healthy weight is important for both men and women embarking on a journey to parenthood.
Learn more about the relationship between weight and fertility and how the team at Penn Fertility Care – Lancaster General Health can help you achieve your goals.