What’s the Skinny on Weight and Fertility?
At 33 years of age, Georgina (not her real name) and her husband desperately wanted babies. They had been trying to fall pregnant for a number of years but with no success. With Georgina’s BMI creeping up to 50, her doctors and the fertility clinic suggested that she needed to lose weight before she would be accepted into fertility treatments. Georgina tried everything – personal trainers, many and varied commercial dieting programs, even surgery (lapband). As her weight remained stagnant, her desperation and indeed her depression increased making it even more challenging for her to lose sufficient weight to make a difference.
This is such a common story, and over the years I have seen many women in both my general practice and weight management clinic, who have been overweight and wanting to get pregnant.
It is now recognized that being overweight can significantly affect our fertility, with fertility decreasing as BMI (body mass index) increases. Being significantly overweight can alter the circulating hormones in your blood including changes in the balance of sex hormones. Storing weight around your abdomen in particular, causes an increase in several circulating hormone levels including insulin which, in turn, results in insulin resistance, increased androgen levels from the ovaries and also increased oestrogen levels. These hormonal changes can make it more difficult to fall pregnant.
Weight Problems and Fertility in Women
A woman is considered fertile if she can conceive within twelve months of trying to fall pregnant. From research we know that:
- Not all overweight women are infertile.
- Infertility in women with a BMI over 30 primarily relates to ovulatory dysfunction (although we are only talking about weight related causes of infertility, not all causes of infertility).
- Women with a BMI greater than 30 are three times more likely to present to their Dr with fertility problems compared to women with a normal BMI.
- Rates of infertility increase by 4% for each additional BMI unit over a BMI of 30.
- There is a significant correlation between a BMI over 25 and an increased time to conception.
- For women using assisted reproductive techniques, the chance of becoming pregnant reduces with increasing maternal BMI.
There is still much research being done regarding the relationship between infertility and increased weight, and the mechanisms involved are very complex. In simple terms, when we eat carbohydrates, there is an increase in glucose /sugar in our blood, this causes our pancreas to produce a hormone called insulin. Insulin causes cells in our muscles and liver to absorb, utilize, and store any excess glucose, thus decreasing blood glucose levels so that they return to normal.
However if our energy, or sugar intake (from food/ drinks) is well above our needs, we store the excess energy in the form of central abdominal fat. These fat cells produce another hormone that blocks the muscle and liver cells from responding to insulin. This means that we become insulin resistant, which results in a rise in blood glucose and insulin levels.
So – How does this affect our fertility?
In our brain we have a gland called the pituitary gland, which is involved in regulating ovulation by producing our sex hormones. Instead of becoming resistant to insulin however, the pituitary cells become oversensitive to insulin and pump out large amounts of hormones that disrupt ovulation – hence ovulatory dysfunction.
Menstrual cycle disturbance and Polycystic Ovarian Syndrome
Having a BMI greater than 30 is often associated with menstrual cycle disturbances. Studies indicate that 30%-47% of overweight and obese women have irregular periods, which correlates with increasing BMI and abdominal obesity. Moreover, being significantly overweight in childhood and early adult life increases the risk of irregular periods during the reproductive years.
In our clinic women often ask whether Polycystic Ovaries (PCO) and Polycystic Ovarian Syndrome(PCOS) are actually the same thing. While they are related, it is important to understand the differences.
Polycystic Ovaries occur when the ovaries contain multiple small peripherally situated cysts. While women with Polycystic Ovaries have an increased risk of developing PCOS (and may or may not be overweight, or may or may not have menstrual irregularities), they do not necessarily do so. In PCOS there are other metabolic abnormalities including increased androgens as well as an increased BMI.
PCOS is the most common endocrine pathology in women and affects 4%-18% of women during their reproductive years. It refers to a collection of findings that may include:
- Multiple peripherally situated ovarian cysts as seen on an ultrasound
- Raised androgen levels
- Irregular periods with no ovulation, or even complete cessation of periods
- Increased body hair
- Increased BMI
- Infertility, although this depends on the severity of PCOS
THE GOOD NEWS: Benefits of weight loss for women with PCOS.
Studies show that even a modest weight loss of 5%-10% can cause significant improvements in menstrual regularity and fertility. This degree of weight loss (5%-10%) can improve insulin resistance, ovulation rate, and conception in women with or without PCOS – even when one’s BMI remains above the ‘healthy’ range. Importantly however, research also shows that if women can reduce their BMI to below 35 before conception this reduces the risk of pregnancy associated complications.
Ideally, it is important to consider weight management before reaching the stage of trying to get pregnant. However, it is never too late – Remember that even modest weight losses improve both fertility and pregnancy.
Obesity and fertility in men:
There are fewer studies examining the impact of weight problems on male fertility specifically. However, recent research does show that obesity affects the development of sperm. The precise mechanism is still under investigation, however we do know that insulin resistance in men produces hormonal changes, which result in:
- Reduced total sperm production and concentration
- Reduced sperm motility (ability to move)
- Increased DNA fragmentation.
This means that it is also important for men seeking to have children to maintain a healthy weight.
Overall – the take home message is good. If you can achieve 5%-10% weight loss and sustain this for at least twelve months (and hopefully longer), there is a good chance that weight related infertility and menstrual problems can be improved.
The Shrinked and Shrinked Plus programs provide you with all of the tools you need to achieve this. The combination of calorie restriction and healthy food choices, regular exercise, and working to develop a healthy relationship with food and changing old unhelpful habits will set you up to successfully manage your weight for life!
Finally – Back to Georgina – did she ever fall pregnant?
Yes!! Georgina commenced our in-clinic version of Shrinked. She certainly had her challenges. Progress was up and down and she often despaired that she would never get pregnant. However Georgina persevered and lost about 10% of her starting weight. Then despite her BMI still being just over 40, she fell pregnant, carried her bub to term, and is now a very proud mum who continues to focus on her weight management and health journey!