Recently, Dr Makrakis gave a lecture in the 10th International Congress on Obesity; the topic was ‘The impact of female obesity on in vitro fertilization outcomes’. The main points of his lecture are summarized as follows:
Obesity seems to be the new worldwide epidemic. In USA and Europe 60% of all women are overweight (BMI>25 kg/m2), 30% of them are obese (BMI>30 kg/m2), and 6% of them are morbidly obese (BMI>40 kg/m2). Obese women have a threefold risk of infertility compared to women with normal weight; in the presence of irregular cycles, infertility is usually associated with oligo-anovulation, whereas in the presence of regular cycles (where the probability of pregnancy is reduced by 5% for every BMI unit that exceeds 29 kg/m2) infertility may be associated with anovulation (which may underlies even with regular cycles), with the release of oocytes with reduced fertilization potential or with endometrial abnormalities. Obesity can be main, secondary or accompanying infertility factor and in any case, there is a high prevalence of overweighed and obese women who need IVF. The impact of obesity on IVF outcomes is debatable, but it has to be mentioned that according to the British Fertility Society guidelines, infertility treatment should be deferred until BMI<35 kg/m2, or even until BMI<30 kg/m2 in young women with good ovarian reserve.
Even though there is no evidence-based consensus, obesity may have negative effects on ovarian stimulation parameters (need for higher doses of drugs, longer duration of stimulation, fewer retrieved oocytes), on oocyte and embryo quality (fewer mature oocytes, embryos of poorer quality), on fertilization rates, on embryo transfer (more difficult technique), and on endometrium (impaired receptivity). The final consequences seem to be the reduced implantation and pregnancy rates, as well as the increased miscarriage rates in the overweighed and obese women which have been reported in many studies. Women who are planning to get pregnant or to enter IVF programs should be advised to lose weigh before starting so, as very strict diets are not allowed during pregnancy or while on IVF.
(More details can be found in the powerpoint presentation of Dr Makrakis, at the link Scientific Symposia and Meetings - Publications)