Healthy Weight and Fertility—What's the Connection?

Content medically reviewed by Haley Meyer, MD

Fertility struggles in both men and women have been linked to both obesity and being underweight. For those trying to conceive or those who are facing difficulties, achieving a healthy weight is often recommended.

You’re considered to be at a healthy weight when your body mass index (BMI) is between 18.5 and 24.9. While BMI is not a perfect measure of health, it is a statistic that can be used to help inform health risk. A high BMI, one that’s over 25, has been linked to –

• Abnormal menstrual cycles, which impact conception
• Decreased pregnancy rates
• Higher rates of miscarriage
• Taking longer to become pregnant

“People who are of higher weight, including those who are obese, can still become pregnant and have a healthy pregnancy and delivery,” said Dr. Haley Meyer, OB/GYN at Essentia Health. “However, weight is an important factor that can impact the function of the female reproductive system.”

How Does Excess Weight Impact Fertility?

Several factors work together to form the female reproductive system, which regulates menstrual periods, ovulation, conception, and implantation—the process of an embryo attaching to a uterus.

“When one of these factors does not function properly, the risk for conception issues increases,” Dr. Meyer said. “For example, a hormonal imbalance can lead to irregular periods, which can make it difficult to predict when ovulation will occur.”

Obesity and carrying excessive amounts of body fat can impact the female reproductive system, mainly by disrupting hormone production, decreasing egg quality, increasing blood sugar, and lead to health issues such as polycystic ovary syndrome (PCOS).

Anovulation

Anovulation occurs when the ovaries do not release an egg during the menstrual cycle. Obesity is often associated with insulin resistance, which can lead to elevated levels of insulin in the bloodstream. High insulin levels can disrupt the production of sex hormones, further affecting ovulation.

Polycystic Ovary Syndrome (PCOS)

Carrying extra weight is a major risk factor for PCOS, a common hormonal disorder that affects women of reproductive age. PCOS can cause irregular periods, ovarian cysts, and hormonal imbalances, all of which can contribute to infertility.

Egg Quality

Research suggests that obesity can negatively impact the quality of eggs the ovaries produce. Lower egg quality can reduce the chances of successful fertilization and implantation, even if ovulation occurs.

Increased Miscarriage Risk

Pregnant people who are obese have a higher risk of miscarriage compared to pregnant people of a healthy weight.

How Much Weight Do I Need to Lose to Conceive?

The general recommendation is to reach and maintain a BMI between 18.5 and 24.9. But the good news is that even moderate weight loss can positively impact fertility for women. Providers recommend that those hoping to become pregnant lose 5% to 10% of excess weight to restore normal reproductive functioning. This is often enough to improve your chances.

“Achieving and maintaining a healthy weight is not just about the numbers on the scale,” Dr. Meyer said. “Leading an overall healthy lifestyle with exercise and good nutrition is equally important. It is also important to consider metabolic health and how this can affect conception and pregnancy.”

Remember that a healthy weight for one person may not be the same for you. If you’re concerned your weight is affecting your fertility, your Essentia Health provider can help you determine a healthy body weight and recommend other changes and treatments to boost fertility.

Weight Loss for Conception

Reaching a healthy weight is not always easy. Work, family obligations, and focusing on conceiving can consume much of your time. But the closer you are to a healthy weight, the closer you become to getting pregnant and having a healthy pregnancy.

The key is to identify areas of improvement, start small, and develop strategies to be consistent.

• Clean up your diet. The first step is to eliminate or limit processed foods, sugary drinks, and unhealthy fats. Try to find healthier alternatives, especially when snacking, such as fruit, nuts, or yogurt with minimal added sugar. Also, try to increase your intake of fruits, vegetables, lean protein, and whole grains.
• Move regularly. Aim for at least 150 minutes of moderate-intensity aerobic exercise per week, such as brisk walking, jogging, or swimming. It can be easier if you find an activity you like and commit to it for 30 minutes about five times per week.
• Tackle stress. Chronic stress can negatively impact hormone levels and fertility. Engage in stress-reducing activities that also burn calories, like gardening, taking a walk in nature, or playing with your pet—whatever you find enjoyable. 
• Talk with a weight-loss specialist. If you find it difficult to lose weight after making lifestyle changes, a weight loss specialist may be able to help you reach your goals. They can develop a weight-loss plan for you and help you stick with it.

Talk with a Fertility Specialist

Navigating weight loss, fertility issues, and other life factors can be challenging. You’re not alone in your journey. Providers at Essentia Health can help by providing guidance, diagnosing and addressing any underlying conditions, and recommending fertility treatments.