Excess weight can interfere with conception [1]. This applies to both men and women. Being underweight can also lead to fertility issues.
What is the optimal weight for a future mom for conception?
It’s more helpful to talk about the ratio of weight and height — the body mass index (BMI) than weight. Doctors recommend achieving a BMI of 18.5 to 25 before you plan to conceive [2]. A BMI of 18.5 or less disrupts the regularity of menstrual cycles and can lead to a complete stop of ovulation. Without ovulation, there is no pregnancy [3].
A BMI of 30 or higher can also lead to a lack of ovulation. Early miscarriages are also statistically more common in women with a high BMI [2]. According to the American Society of Reproductive Medicine, a BMI of greater than 30 reduces even the chances of success with IVF [3].
Does the weight of the future father matter?
Low motility and low sperm concentration are more common in overweight men than in men of average weight. Presumably, this is due to the fact that excess adipose (fat storage) tissue affects the level of testosterone and other hormones important for reproduction. Every 20 lbs (9 kg) of excess weight reduces the chances of becoming a father by 10% [4].
So, you need to lose weight before you go to the doctor about infertility?
No. You should start by contacting a doctor. Together, you can develop a weight loss and conception plan. Sometimes the same factors that lead to infertility also provoke weight gain — and it is impossible to get rid of them with diet and exercise alone. For example, many women with polycystic ovary syndrome (PCOS) are overweight, and this is a vicious circle: PCOS contributes to obesity, and obesity exacerbates PCOS. Women with polycystic ovaries may need additional treatment for weight loss, including medications that regulate insulin resistance [3].
