How can we improve the chances of pregnancy for women who are obese?

How can we improve the chances of pregnancy for women who are obese?

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.

La obesidad se asocia a alteraciones menstruales, con mayor frecuencia por la presencia del síndrome de ovarios poliquísticos
  • Obesity is associated with menstrual disorders, most often due to the presence of polycystic ovarian syndrome
Las mujeres con obesidad grave tienen un 50% menos de probabilidades de quedarse embarazadas
  • Women with severe obesity have a 50% less chance of achieving pregnancy
Por cada punto de incremento en el IMC se reduce la posibilidad de embarazo un 10%
  • For each point increase in BMI, the chance of pregnancy is reduced by 10%

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 fertilisationICSI: intracytoplasmic sperm injection) and it has been linked to a:

  • Poorer ovarian response
  • Poorer quality of oocytes obtained
  • Poorer endometrial receptivity with lower implantation rate
  • Increased number of miscarriages

Or a combination of all these factors

This translates into a poorer prognosis for the ART outcome in women with obesity, both in cycles with their own oocyte and in cases of donor oocytes. The BMI of the woman is important in this second type of ART because of its impact on endometrial receptivity.


There are currently effective medical treatments available to manage obesity, which produce safe weight loss in a reasonable amount of time and which can be implemented in these types of patients with very good results in terms of overall health and fertility.

Instituto Bernabeu, at the forefront of this type of treatment, has a Pro-Fertility Obesity Treatment programme aimed at women with obesity who are looking to become pregnant, under the guidance of an Endocrinology and Nutrition specialist who is an expert in obesity and fertility.

Dr Pino Navarroan endocrinologist and Director of the Endocrinology and Nutrition Department at Instituto Bernabeu


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