Revised 2023
How do I figure out if I am 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). There are many tables available online (search term: BMI table). Enter your height and weight into the tool to see your BMI. A BMI between 19 and 24 is considered normal; 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.
How does weight affect fertility in individuals with female reproductive anatomy?
Many underweight, overweight, and obese individuals have no problem getting pregnant. But others will have problems conceiving, most often due to ovulation problems (failure to release eggs from the ovaries). A BMI of 18.5 or less (underweight) often causes irregular menstrual cycles and may cause ovulation to stop altogether. Individuals with less than normal BMI should work with their doctor to understand the cause of this situation and develop strategies to correct it. A BMI in the obese range may also lead to irregular menstrual cycles and ovulation. However, even obese individuals with normal ovulation cycles have lower pregnancy rates than normal-weight individuals, so ovulation is not the only issue. A visit to a healthcare professional before becoming pregnant can help identify other disorders related to obesity that impact pregnancy, such as thyroid disease, insulin resistance, and diabetes.
Does obesity affect the chance of getting pregnant with treatment and having a healthy baby?
There is substantial evidence that obesity can impact the success rates of in vitro fertilization (IVF). Studies have indicated lower pregnancy rates and higher miscarriage rates in individuals with obesity. Those with obesity are at an increased risk for developing pregnancy-induced (“gestational”) diabetes and high blood pressure (pre-eclampsia). Additionally, individuals with obesity have a higher likelihood of requiring delivery by cesarean section. Children of individuals with obesity are at an increased risk for birth defects and having a high birth weight.
Are there fertility problems associated with obesity in individuals with male reproductive systems?
Obesity in individuals with male reproductive systems may be associated with changes in testosterone levels and other hormones important for reproduction. Overweight and obese individuals may more frequently exhibit low sperm counts and reduced sperm motility compared to those with normal weight.
Should I try to lower my BMI if I am in the obese category before I try to get pregnant?
You should first consult with a healthcare provider. They will consider all factors, including your age and any other infertility factors, before recommending whether you should try to lose weight first. Changing your diet and lifestyle (for example, exercise) combined with a program that may provide group support is effective but not always the appropriate first step if your age or BMI is above 40. Weight loss surgery (bariatric surgery) is the most effective treatment for weight loss in individuals with a BMI greater than 40.