The extent of the issue
Obesity is a public health issue both in the general population and in women of childbearing age. Far from improving, the problem has progressively increased over the last few years.
A study published in the journal The Lancet concludes that 13% of the world population has weight issues. In Spain, there is a growing trend in the number of people suffering from this illness which is particularly alarming as it positions Spain as the second European country, after the United Kingdom, with the largest number of cases of obesity and excess weight.
The prevalence of obesity is high in the USA and Europe and it is increasing in practically all countries. In the USA, over 36.5% of adults are obese; obesity (BMI: Body Mass Index ≥ 30 kg/m2) during a woman’s childbearing age affects 31.8% of women between 20 and 39 years of age and this figure increases to 58.5% when excess weight and obesity are combined.
The impact of obesity on fertility
Fertility issues in obese women (BMI ≥ 30) are, in most cases, linked to ovulatory dysfunction and, in some cases, to polycystic ovary syndrome. Furthermore, it should be highlighted that in women with normal ovulatory cycles, obesity itself is linked to a lower spontaneous pregnancy rate and an increase in the time taken to get pregnant. A recent study found that obese women who are in the latter stage of their reproductive years (35 to 49 years of age) have significantly lower levels of AMH (anti-Müllerian hormone, a hormone that provides information on ovarian reserve). That is, up to 65% compared with women of the same age and normal weight.
What this tells is that obese women will have more issues getting pregnant naturally, will take longer to do so and also have less real time in which to achieve it, even if they have apparently normal cycles, because they appear to have a lower ovarian reserve. Numerous studies prove that a 5 to 10% weight loss leads to a notable improvement in their prognosis.
Assisted reproduction treatment (ART) in obese women
The data suggests that, as a woman’s BMI increases, there is an increased failure rate following ART (IVF: in vitro fertilisation; ICSI: intracytoplasmic sperm injection) and it has been linked to a poorer ovarian response, poorer ovarian response, poorer quality of oocytes obtained, poorer endometrial receptivity with lower implantation rate and increased number of miscarriages, or a combination of all these factors
A meta-analysis analysing 609,881 IVF/ICSI cycles, published in Hum Rep Update (2019) confirms a lower live birth rate in women with a BMI of 30 kg/m2 compare to women with a normal BMI and in other similar studies a higher rate of miscarriage was also found. An increase in the prevalence of other types of complications, such as ectopic pregnancies, ovarian hyperstimulation syndrome among others, has not been demonstrated.
At Instituto Bernabeu we have a Pro-fertility medical treatment for obesity aimed at those obese women who are trying to conceive with the objective of achieving a significant weight loss (5-10%) in a reasonable time and in a safe manner, under the guidance of a medical specialist in Endocrinology and Nutrition who is a fertility specialist.