How Weight Affects Fertility?

Quick Bites

  • You have better chances of conceiving and having a healthy baby if you are at a healthy weight
  • A healthy diet and regular exercise helps improve chances of conception
  • Being an unhealthy weight causes hormonal imbalances and problems with ovulation in females
  • Overweight males have lower quality sperm



The journey to achieving pregnancy is different for everyone. Some couples get pregnant by just having sex, while others seem to find themselves struggling with infertility for months or even years in some cases. Infertility is the most common reproductive problem in today's generation. In many cases, individuals do not have control over the factors that contribute to their infertility; there are a few modifiable factors that play a role in getting pregnant. An example of such a modifiable factor is the weight.

By maintaining a healthy BMI (Body Mass Index), not only can you improve your chances of a successful pregnancy, but also reduce the risk of pregnancy complications. Researchers have found that being at a healthy weight can be beneficial when it comes to conceiving. Of course, it is crucial to note that being at a healthy weight does not guarantee the best fertility, but being underweight or overweight reduces your chances of natural conception. In the upcoming sections, we will talk about how being overweight or underweight can delay your pregnancy.

In this article


What is healthy body weight?

Having a healthy weight is good for your reproductive and overall health. It prevents you from many chronic health conditions like heart diseases and diabetes. Healthy body weight also keeps your hormonal balance under check, preventing any issues related to ovulation (in women) and maintaining good sperm health (in men). But what is the ideal body weight?

It brings us to the Body Mass Index (BMI). This measures how much weight one should have depending on their height and indirectly measures the body fat. Body mass index is calculated by dividing your weight in Kgs by the square of your height in meters. You can also use any BMI calculator that is available on the internet.

General guidelines relating to BMI one can fall into these categories:[1]

Under 19- Underweight

19-24- Normal

25-29- Overweight

Over 30- Obese

It is a screening tool that is easy, though very limited, as it doesn't take things like nutrition habits, muscle mass, medical history, activity, or basically anything except your height and weight into consideration. Hence, if you are planning to conceive or are facing a problem in natural conception, consult a fertility expert for a thorough assessment.


How weight affects your chances of successful pregnancy?

Weight is known to influence the quantity of estrogen in your body. Most of you must be aware that your ovaries produce estrogen, but a lot of you don’t know that adipose tissue or fat cells also secrete some amount of estrogen. Estrogen is necessary to release eggs from your ovaries (ovulation).

Under ideal body weight, your body produces enough estrogen that helps you ovulate every month as per your menstruation cycle. However, when you are obese or overweight, along with your ovaries, the adipose tissue (fat tissue) also starts producing estrogen. This high level of estrogen causes hormonal imbalance, preventing regular ovulation. Studies show that obese women are less likely to conceive within 12 months of unprotected sex than women with normal body weight.[2]

Your body needs a fine balance between the hormones to ovulate, and having a high or low estrogen can throw off that balance. In general, the estrogen level in your body keeps on rising to a level that releases the eggs from the ovarian follicles, and then the level decreases. On the flip side, your ovaries make less estrogen if you are underweight. If you are significantly underweight and your menstruation can stop altogether if you are underweight (amenorrhea).[3]

With obesity comes other health complications, one such condition is insulin resistance. Insulin resistance can not only lead to type 2 diabetes, but it also harms your fertility. The job of insulin (a hormone secreted by the pancreas) is to transfer glucose from the bloodstream to the cells. But when your body is insulin resistant, cells don’t listen to insulin’s request to move glucose to the cells. In such conditions, the pancreas will detect the high glucose level and will produce more insulin to remove glucose from the blood to the body cells. That means the body is producing more insulin than normal to remove the glucose. This increased insulin causes metabolic disturbances that can affect ovulation and hence, delay conception. Not only this benign overweight also affects male fertility as the studies show that man who are overweight or obese have lower quality sperms, faces erectile dysfunction and low libido.

Researchers have found that being overweight can also impact women's ability to carry the pregnancy to full term and increases the risk of pregnancy complications. According to the American College of Obstetricians and Gynecologists (ACOG), babies that are born to obese women, with a BMI of 30 or higher, have higher chances of being born with defects like heart problems and neural tube defects. The ACOG also alerts that the risk of pregnancy-related complications like diabetes, preterm birth, and high blood pressure is higher in overweight women.[4]

Research published in the Journal Human Reproduction states that women who have a BMI higher than 25, miscarry chromosomally normal fetuses more than women with normal BMI. The exact mechanisms and reasons for increased miscarriages among obese and overweight women are not known presently. But it is believed that endocrine problems like PCOS and insulin resistance play a role in it.[5]

Not only this, but the rate of successful pregnancies with artificial technologies is also low for overweight women as compared to women with normal body weight. A published study in the Journal of Human Reproductive Sciences, states that women with a higher BMI, do not respond well(as compared to those with a normal BMI) to fertility treatments like IUI and IVF.


Can reaching a healthy weight help you conceive?

Reaching a healthy weight can help you get pregnant if the cause of your infertility is determined as weight. Every woman is different, but researches have shown that for losing weight in overweight or obese women raised their chances of getting pregnant.[6] Losing weight also helps in getting the menstrual cycles back to normal. Women who are underweight and need to gain weight before conception should gain weight gradually. They must talk to their doctor about how to increase weight safely.


Pregnancy risk and complications associated with obesity

Being overweight or obese during pregnancy can raise the risk of complications during pregnancy. Even if you are not already overweight or obese, gaining too much weight than recommended can also be a problem. Some of the complications caused due to being overweight during pregnancy are:

  • Gestational hypertension- High blood pressure during pregnancy may lead to a severe complication known as preeclampsia.
  • Gestational diabetes- It is a type of diabetes that starts during pregnancy and increases the risk of lifetime type 2 diabetes and obesity. It can also cause low blood sugar in the newborn. It also causes the unborn baby to become larger, which can injure the mother during birth or the baby.
  • Increased risk for C-section

Also, babies born to mothers who are overweight are at higher risk for health problems like:

  • Neural tube defects
  • Heart defects
  • Low blood sugar and bigger size of the body (If the mother has gestational diabetes)
  • Obesity
  • Type 2 diabetes
  • High cholesterol

Whereas, babies born to underweight mothers are at higher risk for health problems like premature birth and low birth weight.[7]

Talk to your doctor about healthy weight loss or gain to help lower the risk of these problems.


Tips for a healthier weight to enhance fertility

If you have doubts about your weight and are finding it difficult to conceive, you must talk to your doctor. Struggling to conceive can be lonely, completely isolating, and devastating. And finding out that your weight is a factor that is causing the problem can add to the frustration and confusion. If losing weight is a significant challenge for you, discuss with your doctor, and determine what steps can be most helpful for you. They either suggest a consultation with a dietician or offer a few lifestyle changes which help in making a difference.

Researches have proved that 5-10 percent weight loss can help in improving fertility outcomes.[8] So it is possible that you achieve your goals with modifications in your lifestyle like dietary changes and exercising. And remember anything that promises rapid weight loss through cleanses, too-good-to-be-true workouts, or supplements, is not the best for you and they could even be dangerous.

If you're underweight or are recovering from or struggling with an eating disorder, it is beneficial that you speak openly about it with your doctor. They can help you by connecting you to dietitians who specialize in EDs, or even therapists that can help and guide you through these complex food and weight issues.

If you are taking any regular medication or supplements, talk to your doctor about its effects on your fertility. The doctor will review your medicine and will ensure that they are safe to consume during pregnancy and are not hindering your ability to get pregnant. Do not forget to include any supplements or over-the-counter medications and not just prescriptions. Your doctor can do a full work-up that will help in determining if something else besides your weight is causing infertility, as there can be other reasons why you are facing trouble. Your doctor can point out ways to reduce the anxiety and stress that is often related to infertility or connect you to a therapist who specializes in everything pregnancy.

Apart from talking to your fertility expert, you can try these steps to reach a healthier body weight:

  • Set a realistic weight goal to keep yourself active and motivated. Aiming for losing half to one kilogram per week until you reach your goal weight is a realistic goal.
  • Follow a healthy diet including lots of fruits, vegetables, wholegrain, cereals, yoghurt, milk, cheese, lean meat, fish, poultry, eggs, seeds, and nuts.
  • Cut back on discretionary foods like fatty meats, biscuits, chips, cakes, pastries, fast foods, and confectionery.
  • Indulge in plant-based fats like nuts, olive oil, grapeseed oil, and avocados in moderation. It helps in general fertility and regular ovulation.
  • Consume less red meat and more fish like salmon, sardines, and canned light tuna as they are a very good source of omega-3 fatty acids and DHA. They also help in developing the baby's nervous system and reduce the chances of premature birth.
  • Avoid forms of soy, particularly energy bars and powders as it can harm your fertility
  • Cut down sugar levels and try to consume less-processed sweeteners.
  • Drink tea, coffee, and alcohol in moderation. You should also avoid sugary drinks completely.
  • Take multivitamins containing at least 40-80 milligrams of iron and 400 micrograms of folic acid every day.
  • Eat timely and regular meals and try to avoid unhealthy snacking.
  • Swap your screen time for other activities.
  • Get moving every day with regular physical activities like taking the stairs, walking with a friend, walking to the shops, or exercising.
  • Start a diet and exercise plan together along with your partner. This will increase the chances of conception and having a healthy baby.

These lifestyle changes will help in improving your overall health. Begin to make these changes before you start trying to get pregnant. It is recommended you keep these practices up till you conceive and then throughout your pregnancy and beyond.

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List of ReferencesHide

1 . “About Adult BMI”.Centre for Disease Control and Prevention, June 30, 2020.

2 .

Lake JK, Power C, et al. “Women's reproductive health: the role of body mass index in early and adult life”.Int J Obes Relat Metab Disord. 1997;21(6):432-438; PMID: 9192225.

3 .

Grodstein F, Goldman MB, et al. ”Body mass index and ovulatory infertility”. Epidemiology. 1994;5(2):247-250; PMID: 8173001.

4 . “Obesity and Pregnancy”. The American College of Obstetrician and Gynecologists, 27 July 2020.

5 .

Shilpi Pandey, Suruchi Pandey, et al. “The impact of female obesity on the outcome of fertility treatment”. J Hum Reprod Sci 2010 May, PMID: 21209748.

6 .

Erica Silvestris, Giovanni de Pergola, et al, “Obesity as disruptor of the female fertility”. Reprod Biol Endocrinol. 2018;16(1):22. PMID: 29523133.

7 .

Zhen Han, Sohail Mulla, et al. “Maternal underweight and the risk of preterm birth and low birth weight: a systematic review and meta-analyses”. Int J Epidemiol. 2011 Feb;40(1):65-101, PMID: 21097954.

8 .

Thomas A. Wadden, Victoria L, et al. “Lifestyle Modification for Obesity”. Circulation. 2012 Mar 6; 125(9): 1157–1170, PMID: 22392863.

Last updated on: : 28 Sep 2020

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