Being overweight or obese more than doubles the risk of miscarriage for women who are undergoing IVF or ICSI treatment, the annual conference of the European Society of Human Reproduction and Embryology heard yesterday.
One of the researchers behind the finding, Dr. Vivian Rittenberg, from Guy's and St. Thomas' Hospital, London, said that this information should be included in the counseling given to patients before they undertake IVF or ICSI.
"Although there is evidence that miscarriage rates are higher in overweight women who conceive spontaneously, there were conflicting views about the effect of increased weight on the outcome of pregnancies occurring after IVF and ICSI," Dr. Rittenberg said. "The difficulty of interpreting the studies to date is that their thresholds for defining obesity vary, and they assess the outcome in relation to BMI following the transfer of multiple embryos at various stages of development. Our study differs in that we transferred only one embryo at a specific stage of development, and were therefore able to provide clear evidence of the deleterious effect of being overweight on the chances of miscarriage."
Being overweight can lead to a number of other pregnancy risks including high blood pressure, pre-eclampsia, diabetes, premature delivery and post-partum bleeding. Additionally, babies of obese mothers are more likely to have a high birth weight and thus may face an increased rate of delivery by Caesarean section, which in itself can cause complications for both mother and baby.
"Overweight women wishing to get pregnant by spontaneous conception are already counseled to lose weight before trying for a baby," said co-researcher Dr. Tarek El-Toukhy. "Our findings have shown clearly that women undertaking ART [assisted reproductive technology] should be strongly encouraged to heed this advice in order that they can have the best possible chance of obtaining and maintaining a pregnancy."
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Source: European Society of Human Reproduction and Embryology