How Weight Affects Your Chances of Getting Pregnant | Obesity & Pregnancy

Studies have shown that being overweight can increase the risk of infertility by as much as three times. This is the case in both natural and assisted conception with probability increasing an estimated 5% per unit of body mass index (BMI) over 29.

The link between obesity and infertility

Being overweight can have numerous effects on infertility but, ultimately contributes to menstrual cycle disturbances and anovulation. Anovulation is when the ovaries fail to release an oocyte also known as an egg cell. According to the World Health Organization (WHO), obesity is defined as having a body mass index equal or greater than 30

Factors included in the effects of obesity on infertility

There are a number of weight related medical issues that can affect your chances of getting pregnant. Some of these conditions are listed below.

POLYCYSTIC OVARY SYNDROME (PCOS)

PCOS can be a significant factor in infertility and is typically more severe in obese women. While PCOS often develops around the time of initial menstrual cycles it is frequently seen as a side effect of substantial weight gain and may present with symptoms such as:

Irregular menstrual cycles that may be prolonged, excessively heavy, painful, or absent.
Elevated levels of the male hormone androgen which may result in excess facial or body hair, severe acne, and male pattern baldness.
Enlarged ovaries with numerous fluid-filled sacs (follicles) that fail to release eggs regularly.

IMPAIRED ESTROGEN METABOLISM

Estrogen is a sex hormone produced in the ovaries and is essential for reproduction. Estrogen is also found in adipose tissue (fat) therefore excess adipose tissue can lead to increased levels of estrogen which contributes to PCOS.

CHANGES IN THE LEVEL OF FREE TESTOSTERONE

Obesity can lead to decreased levels of sex hormone binding globulin (SHBG) causing increased levels of free testosterone in females also contributing to PCOS.

HYPERINSULINEMIA

Hyperinsulinemia or high levels of insulin in the blood is so closely linked to obesity it is often debated whether obesity is the cause or result of hyperinsulinemia. Excess insulin circulating in the bloodstream impacts various hormones such as follicle stimulating hormone (FSH) and luteinizing hormones (LH), as well as estrogen and progesterone. An imbalance of these hormones can negatively affect egg quality so when ovulation does occur, the possibility of successful conception is reduced.

LEPTIN LEVELS

Leptin is a hormone primarily produced by adipose tissue and high levels have been distinctly linked to the incidence of PCOS. Leptin plays a role in regulating appetite and body weight however; leptin resistance is often present in obese individuals. Insulin plays an important part in the stimulation of leptin secretion therefore the combination of increased insulin and leptin levels are often seen together.

What can be done to improve chances of successful reproduction?

A sensible weight loss program that includes diet changes and moderate exercise have proven to assist in restoring menstrual cyclicity and ovulation thereby improving the chance of successful reproduction.

Are you concerned about how your weight may be affecting your chances of pregnancy? Contact us today for a consultation with one of our reproduction specialists.