A person is considered obese when his or her body mass index (calculated by dividing weight in kilograms over height squared in centimeters) is greater than 30. Obesity increases cardiovascular disease, hypertension, diabetes and infertility risks.

If you want to get pregnant and your body mass index is over 30, a good first step would be a healthy diet and regular exercise plan, which can be gradually incorporated to your daily life. There are several benefits to weight losing; however, it is important that your lifestyle changes are accompanied by a specialized fertility treatment, particularly if you are over 35.

What is obesity?

A person is considered obese when their body mass index (BMI), calculated by dividing weight (in kilograms) by height (in meters) squared, is greater than 30.

  • BMI between 25 and 30 = overweight
  • BMI between 30 and 35 = mild obesity
  • BMI between 35 and 40 = moderate obesity
  • BMI greater than 40 = morbid obesity

According to the World Health Organization (WHO), there are over one billion overweight adults worldwide, and at least 300 million are obese. Obesity increases cardiovascular disease, hypertension, diabetes and infertility risks.

Meanwhile, patients with a BMI of 20 or lower (for example those with anorexia nervosa) present an increased lung disease, malnutrition and infertility risk.

How does obesity affect female fertility?

When compared to normal weight women, overweight women have higher blood estrogen levels. This is caused by their fat cells, which incorrectly metabolize hormones, transforming androstenedione (produced by the adrenal gland) in a type of estrogen known as estrone.

International studies have shown that a 10 kilogram overweight increases a woman’s infertility risk by 10 percent. According to a study by the Amsterdam Academic Medical Center, women with a BMI of 35 have a 26 percent lower probability of achieving natural pregnancy when compared to normal BMI women (i.e. between 20 and 24.9).

Being overweight can affect female fertility in several ways:

  • Estrogen excess alters ovarian function, which could disrupt the normal ovulatory cycle
  • The obesity associated high level of estrogen may also result in the formation of (usually benign) uterine tumors
  • Women whose obesity began during childhood have a higher risk of amenorrhea, a condition in which menstrual cycles are absent
  • Obese women have an increased risk of miscarriages and a lower success rate when undergoing assisted reproduction treatments, since an excess in weight interferes with a proper absorption of ovulatory induction medication
  • Obesity is associated with diseases like polycystic ovarian syndrome and hypothyroidism. It also is believed to be partially responsible for metabolic disorders such as insulin resistance

How does obesity affect male fertility?

Obesity also affects male fertility:

  • Obese men have 15 percent fewer sperm in the ejaculate than normal weight men
  • Obesity decreases sperm motility and therefore their ability to fertilize the egg
  • Overweight men tend to have low testosterone levels and are prone to erectile dysfunction
  • Obesity is associated with an increased sperm DNA fragmentation rate, which can cause implantation failure and increase miscarriage risk in the pregnancy’s first trimester.

Obesity risks during pregnancy

While many overweight women succeed to conceive, it is important to understand that they also have a higher risk of complications during pregnancy and childbirth, such as:

  • Preeclampsia
  • Gestational diabetes
  • Spontaneous miscarriages
  • Caesarean section need
  • Postpartum infection

These conditions also affect the newborn’s health, causing:

  • Overweight
  • Under weight
  • Obesity tendency
  • An increased risk of developing hypertension, cardiovascular disease and diabetes

These are considered as high risk pregnancies, so they should be carefully monitored by a maternal fetal medical specialist.

What can I do to improve my fertility?

If you want to get pregnant and your body mass index (BMI) is over 30, it is recommended that you avoid eating too many carbohydrates, saturated fat or sugar and enrich your diet with fruits, vegetables, grains and lean protein sources. Also, you should gradually incorporate an exercise routine into your daily life. Walking is a great way to start.

Sometimes it is only necessary for a woman to lose 5 percent of her body weight for ovulation to be restored and pregnancy achieved; however, it is important to note that although the benefits of losing weight are very significant, this change in your style life must be accompanied by a specialized fertility treatment, particularly if you are over 35.

Diseases such as polycystic ovary syndrome, insulin resistance and hypothyroidism can hinder weight loss, so it is recommended that you start your fertility treatment with a blood test to discard all of them. These
conditions are usually easy to diagnose and, once they are under control, it will be much easier to lose weight.

At Ingenes we consider overweight as a problem that requires a multidisciplinary treatment. In order to do this, we offer useful workshops such as yoga and nutrition, as well as an emotional support unit and our assisted reproduction treatments. This integral treatment will help you improve your overall health, but will also allow you to conceive and achieve a healthy pregnancy