If you are worried that your weight is affecting your fertility, calculate your BMI! BMI, aka body mass index, is how your doctor will refer to your weight and is a measure of body content based on height and weight. A BMI within the 19-25 range is considered normal while a BMI in the 25-30 range is considered overweight. A BMI over 30 is considered obese. If your BMI is under 18.5, you're considered underweight. Your BMI does not have to be within the normal range to become pregnant but any movement towards the normal range may help you start ovulating.
Being underweight can impact fertility. Women with lower than normal BMI either because of nutrition or extreme exercise (think of Olympic gymnasts or ballerinas and extreme endurance athletes) can experience hypothalamic amenorrhea (a fancy way of saying that a women’s menses stop due to disruption of the normal hormonal change). Of course no period for these women means no ovulation and hence no pregnancy. Usually weight gain and increased body fat will cause them to resume normal periods (go for the extra slice of pizza!).
Being overweight or obese can impact fertility. Women who are overweight or obese are at increased risk of having polycystic ovarian syndrome, where hormonal imbalances prevent them from having normal periods and hence ovulating. Most of these women will notice that even losing 10 to 20 pounds will cause them to resume their normal cycles and start ovulating again.
Your partners' weight matters too!!! Unfortunately we women always think it is our fault, but studies have shown that men with a BMI over 30 (which is considered obese) have a lower sperm count. If you and your partner are both overweight or obese, then start an exercise or nutrition regimen together. In addition to increasing sperm counts and successful ovulation, couples who exercise together have more frequent intercourse (what a fun way to burn some calories!). This may be doubly beneficial to your chances of conceiving!
Remember weight loss and achieving a weight closer to a normal BMI will not only make you more likely to conceive but will also help you have a more healthy pregnancy. It will decrease your chance of having miscarriage, gestational diabetes, preeclampsia and as well as your need for a cesarean section. Additionally, a small weight change that returns your cycles to normal can reduce the need for medications (and their side effects) to improve fertility. Be sure to talk to your doctor if you think your weight is affecting your fertility!