Learn how your weight can affect your ability to conceive, and what you can do to support your fertility.

You’re probably aware that being overweight is associated with a range of health issues such as type 2 diabetes, heart disease and cancer. However, recent findings show that there is also a definite negative association between obesity and fertility in females and males.

Essentially, it appears that the more overweight you are whilst trying to get pregnant, the lesser your likelihood of conceiving and delivering a healthy baby. Below, we discuss the effect of obesity on fertility to highlight the importance of being a healthy weight if you plan to have a family of your own.

Learn more about obesity and pregnancy.

What is the ideal weight for conception?

Your body mass index (BMI) is a great indicator of whether you are a healthy weight, which, as discussed above, affects your fertility. This metric is calculated by your weight and height. A healthy BMI is anywhere between 18.5 and 24.9, while a range of 25 to 29 is considered overweight. Above 30 is categorised as obesity.

Obesity and fertility in females: does being overweight affect chances of conception?

Being overweight can affect fertility in females by causing a variety of hormonal, ovulation and menstrual problems, which in turn hinder the ability to conceive.

Hormonal imbalances

Hormones regulate your menstrual cycle, and a careful balance is needed to do this properly. However, overweight women have more leptin, a hormone produced in fatty tissue that can disturb the overall hormonal balance and negatively affect fertility.

The amount and distribution of fat has an influence on the menstrual cycle via hormonal activity. Excess fat, especially in the abdominal area, is associated with insulin resistance and reduced levels of sex hormone-binding globulin, which modulates androgen and oestrogen production. These knock-on effects lead to a greater risk of irregular menstrual cycles, which then impedes fertility.

Ovulation issues

Disruption to the fine hormonal balance that modulates the menstrual cycle can also lead to a greater risk of anovulation (whereby the ovaries fail to release eggs). Research shows that if you have a BMI over 27, you are three times less likely than women in the healthy BMI range to ovulate and therefore conceive.

While many overweight women still ovulate, the quality of their eggs may also be affected, with studies suggesting that every BMI unit over 29 lowers the likelihood of conception within 1 year by approximately 4%.

Obesity is also associated with polycystic ovary syndrome (PCOS), a common cause of low fertility or infertility. Women with PCOS may have infrequent or prolonged menstrual periods or excess male hormone (androgen) levels. The ovaries may develop numerous small collections of fluid (follicles) and fail to regularly release eggs.

Assisted reproduction issues

Obesity is associated with lower rates of successful assisted reproduction, including in-vitro fertilisation (IVF), intracytoplasmic sperm injection (ICSI) and ovulation induction.
More specifically, the likelihood of a live birth from IVF is 20% lower for obese women and 9% lower for overweight woman compared to those with a healthy BMI.

Obesity and male infertility

Obese men may also experience a reduction in fertility levels, with obesity not only affecting the quality and structure of sperm. It also has a more indirect influence, being associated with health conditions like diabetes and sleep apnoea (both of which are linked to reduced testosterone and erectile dysfunction).

That said, it’s important to note that weight loss in obese men may considerably improve sperm count and quality. It is recommended to reach a healthier weight three months in advance of attempting to conceive, as sperm takes this amount of time to develop. Essentially, the healthier a man’s weight during this period, the better your chances of getting pregnant.

Obesity and fertility regain

With all of the above information in mind, the good news is that it is also possible to reverse the cycle and increase your fertility levels, simply by losing weight and once again achieving a healthy BMI. However this will involve, in the very least, setting some goals for diet and lifestyle changes.

Get professional support with weight loss before pregnancy

If you have previously failed many weight loss attempts through diet and exercise, and your BMI remains at an unhealthy level, there is another option in that you may be eligible for weight-loss surgery with Newcastle Obesity Surgery.

To be eligible, you must:

• Have a BMI greater than 35 (BMIs lower than this may be considered if suffering from serious health problems related to obesity)
• Have demonstrated that you have failed previous weight loss attempts
• Be fit for surgery (this may be assessed by your surgeon, however other specialist assessments may be required in some circumstances)
• Not drink alcohol to excess, not have a drug addiction or serious uncontrolled psychiatric issues.
• Be willing to continue being monitored by the specialist team

In combination with the surgery, Newcastle Obesity Surgery Centre provides specialist obesity dietitians who will provide expert nutritional assessment and ongoing nutritional care to all weight loss surgery clients, individualised to their needs.

If the above information is of interest to you and you feel obesity surgery may assist you on your path to a healthy pregnancy, begin your journey with Newcastle Obesity Surgery Centre. Book an appointment through our contact form or get in touch on 02 4058 3936.