From: BMJ-British Medical Journal
Being underweight or overweight reduces fertility in women
Body mass and probability of pregnancy during assisted reproduction treatment: retrospective study
Extremes of weight are associated with reduced probability of achieving pregnancy in women receiving assisted reproduction treatment, finds a study in this week's BMJ.
Over 3,500 Australian women, who received assisted reproduction treatment between 1987 and 1998, were divided into five groups according to their weight: underweight, moderate, overweight, obese and very obese. Fertility was defined as the probability of achieving at least one pregnancy throughout the treatment.
The fertility of the moderate group was almost 60% higher than that of the very obese group, and the fertility of the underweight group was also significantly lower than that of the moderate group. When factors, such as age, number of embryos transferred and type of treatment were accounted for, the pregnancy rate among very obese women was half that of the moderate group.
Ways in which extremes of weight can affect fertility include menstrual disturbance and inability to ovulate, but these problems can be overcome through assisted reproduction treatment, say the authors. They suggest that other mechanisms, such as disturbance to the lining of the uterus, may cause reduced fertility.
Jim Wang, Department of Obstetrics and Gynaecology, University of Adelaide, Queen Elizabeth Hospital, Australia
Michael Davies, Department of Obstetrics and Gynaecology, University of Adelaide, Queen Elizabeth Hospital, Australia