Obesity and infertility by Prof Oladapo Ashiru
The World Health Organisation, convened a Global Summit on Safety and Access to Fertility Care between December 4 and 6, 2018 in Geneva, Switzerland. At the event, we made several recommendations on fertility that were of great value to the public and the entire nation. They range from underscoring the fact that infertility is a disease, like any other one, the de-stigmatisation of infertility and its management up to the most current technologies. I will use this medium to explain them to the public. Today I will consider the issue of obesity and infertility.
A WHO evaluation of Demographic and Health Surveys data from 2004 estimated that more than 186 million never- pregnant married women of reproductive age in developing countries were infertile, translating into one in every four couples between the ages 15 and 49.
The science of getting pregnant and having healthy babies is such a complex process that those who get pregnant and bear live healthy babies with ease are, indeed, lucky. Being in good health, with balanced and synchronised hormones, minerals and vitamins, organs and systems, is essential to achieving pregnancy, carrying the pregnancy to term and giving birth to live and healthy babies.
Getting pregnant is not so easy, even for couples who have normal physiological parameters. For example, a couple that has no medical abnormalities including normal weight with a body mass index (BMI of 19-25 kg/m2), has only 80 per cent chance of getting pregnant within one year of having unprotected sex. It gives an insight into how being overweight or obese can decrease your chances of getting pregnant or carrying a pregnancy safely for nine months without complications.
In this article, we will discuss the effect of obesity on fundamental reproductive mechanisms and its relationship with fertility treatment.
Obese women experience impaired fertility in both natural and assisted conception cycles. The mechanism through which obesity affects fertility is, however, controversial. Obesity is characterised by excess fat storage. Definitions of obesity can vary, but the most widely accepted definition is that of the World Health Organisation’s body mass index criteria. A person is obese if his or her BMI is more than or equal to 30 kilogrammes per meter.
There are degrees of obesity: Class 1 (30.0-34.9 kg/m2), Class 2 (35.0-39.9 kg/m2) and Class 3 (more than or equal to 40 kg/m2). Alternatively, although less commonly used, the parameters for the assessment of obesity include waist circumference and waist to hip ratio.
A waist circumference of more than 80 centimetres in women is an accepted indicator of abdominal fat accumulation and also referred to as central obesity. A high body mass index is associated with reduced fertility and an increased risk of complications in pregnancy. The likelihood of pregnancy declines with increasing BMI. In some countries, fertility treatment is denied to obese persons.
According to the Europe Pub Med Journal, a study of 26,638 women aged between 20 and 40 was conducted to determine the association between obesity, menstrual abnormalities and infertility. It was found that women with anovulatory cycles, or irregular cycles greater than 36 days, and hirsutism (male-like hair growth) were more than 30 pounds (13.6 kg) heavier than women with no menstrual abnormalities after adjusting for height and age.
The study also concluded that the more overweight or obese a woman is, the more likely that she would have anovulatory cycles. Women with a single menstrual abnormality, including cycles greater than 36 days, irregular cycles, virile hair growth with facial hair, or heavy flow were also significantly more substantial than women with typical values for these factors. A longer duration of obesity was associated with facial hair.
Another analysis found that teenage obesity was more significant for never-pregnant married women than for previously pregnant married women, and for women having ovarian surgery for polycystic ovaries than for women having ovarian surgery for other reasons. This also supports an association of obesity with anovulatory cycles. These findings showing evidence of abnormal ovulation, menstrual abnormalities and excess hair growth in obese women may be explained by other recent studies demonstrating an association between obesity and hormonal imbalances.
The American Journal of the National Institute of Health corroborates this when it reports that fertility can be negatively affected by obesity. In women, early onset of obesity favours the development of menses irregularities, chronic oligo-anovulation (reduced to absent ovulation) and infertility in the adult age.