Obesity is known to have various adverse effects on health including heart disease, type 2 diabetes, hypertension, stroke, sleep apnea, and cancer among others. A large percentage of people are not aware of the effects of obesity on fertility. A number of studies have shown that obesity and infertility in both men and women are closely linked, how true is this?
Obesity is defined as having an excess weight that is above the ideal body weight. A person is said to be obese if they are more than 20% of their normal weight. An obese person usually has a Body Mass Index (BMI) of 30 and above.
BMI is a parameter used to measure body weight by relating it to height, it is a person’s weight in kilogram divided by their height in meters (squared). An ideal BMI is within the range of 18.5 and 24.9. Being obese is a risk factor for so many health issues and infertility is one of them.
A number of studies have associated obesity with poor reproductive health in women including irregularities in menstrual syndrome and fluctuations in sex hormones that contribute to infertility in women.
When a woman’s BMI is above 30, it can lead to changes in her hormonal balance. A change in the hormonal balance can reduce the chances of conception in women. Being overweight can also cause insulin resistance which happens when the body is forced to produce more insulin to keep blood sugar levels regulated.
It also causes a reduction in sex hormone-binding globulin (SHBG) whose function is to regulate sex hormones; androgen and estrogen. Insulin resistance and a change in the levels of SHGB can contribute to menstrual irregularities in women which increases the risk of infertility.
Insulin resistance can also trigger anovulation, a condition where the body is not able to release eggs from the ovary adequately. One study found that women with abnormal menstrual and anovulatory cycles have a higher BMI, whereas women who were not as overweight had no problems with their menstrual cycles.
Anovulation may not totally hinder the body from producing eggs but it can affect the quality of eggs produced and make conception difficult. It has also been found that women who ovulate but have a BMI above 29 have a reduced pregnancy rate of 4% within 12 months. Also, obesity can be a side effect of a disease called Polycystic Ovary Syndrome(PCOS) in women.
Although the primary cause of PCOS is known, it is linked to high insulin levels. The condition is characterized by enlarged ovaries that seldom mature or produce eggs that can be fertilized, making conception difficult.
Obesity can also cause complications in pregnancy such as miscarriages and difficulties with conception through in vitro fertilization (IVF).
A combined analysis of six studies that evaluated women within the normal weight range and those who were obese during pregnancy found that women who were not obese had lower chances of having a miscarriage by 10.7% while obese women had a high rate of miscarriage by 13.6%. Also, obese women had more episodes of recurrent miscarriage by 0.4% compared to women with a healthy BMI(0.1%).
Negative IVF treatment outcomes have also been linked to obesity. A research paper published in the journal of human reproductive sciences looked at the impact of obesity on fertility treatment outcomes.
The study reported that obese women found it more challenging to get pregnant through IVF and required higher drug doses than their counterparts who had a healthy BMI. Also, women with a high BMI have low live birth rates through IVF, this means that their chances of having live births is greatly reduced.
Obesity can also affect a man’s ability to impregnate his partner to a large extent. It can cause a dip in testosterone levels and reduced erectile function which jointly contributes to subfertility in men. It basically affects sperm quality and changes the physical and molecular structure of germ cells in the testes and in mature sperm.
Obesity in men can also affect pregnancy outcomes. There is evidence to suggest that obese men are less likely to have live birth through IVF with their partners. A study that used mice as a case model has shown that an increase in weight due to a high-fat diet can cause adverse changes to sperm motility and a decrease in the volume of sperm.
Obesity can also affect the temperature of the scrotum which is necessary for sperm production. Increased fat in scrotal tissues can raise testicular temperature which can impede sperm function.
A study carried out on a large population of Danish men examined the relationship between BMI and sperm concentration. Men in the study who were within a normal BMI range had a better sperm concentration and sperm count than obese and underweight men. They also showed low levels of abnormal spermatozoa. Although the study didn’t relate obesity to poor sperm morphology, it showed that obesity can contribute to reduced fertility in men.
Researchers at the University of Utah, school of medicine sampled a total of 526 patients who were seeking fertility treatment. They measured low sperm count, erectile dysfunction in relation to BMI. They found that sperm concentration and count became lower with increasing BMI, hence causing reduction infertility.
As an obese person, the key to increasing your chances of having a baby is by losing weight. If you are not sure you have a healthy weight, you can check your BMI using a BMI calculator, by inputting your height and weight. A BMI figure between 18.5 and 24.9 is considered healthy if it is below 18.5, it means one is underweight. A BMI between 25 and 29.9 means one is overweight, while a BMI above 30 means one is obese.
You can lose weight by making healthy dietary changes which usually involves cutting back on the consumption of carbs and refined sugar and carrying out regular exercises. You can also consult a dietician to help you work through a weight loss diet plan.
Partners that are obese conceive easily and have healthy babies if they can get rid of excess weight. For better results, you and your partner can team up and work towards losing weight together. Losing weight is not usually an easy process and requires commitment and dedication, but with the right mindset and support from your partner, family, and friends, including your dietician or doctor, it can be a walk in the park.
Originally published on Health in Vitro.
Based on what others are reading
Dr. Amy Marsh, Mar 25 2020