The influence of body mass index to in-vitro fertilisation treatment outcome, risk of miscarriage and pregnancy outcome.

The aim of this work was to evaluate the effects of extreme body mass index (BMI) on assisted reproductive treatment outcome and pregnancy outcome. This is a descriptive cohort study that evaluated 8,145 consecutive in-vitro fertilisation/intracytoplasmic sperm injection-embryo transfer (IVF/ICSI-ET) cycles in which BMI were known, from July 1997 to June 2005 in an inner London major fertility clinic. The data were collected prospectively and analysed retrospectively on women undergoing IVF/ICSI and ET. Patients' weight and height were established prior to treatment. IVF/ICSI treatment was then started using either a long or an antagonist protocol. Patients were divided into five groups: Group A (BMI < 19); Group B (BMI between 19 and 25.9); Group C (BMI between 26 and 30.9); Group D (BMI between 31 and 35.9); Group E (BMI > 36). The main outcomes measured were number of eggs collected, fertilisation rate, number of embryos available for transfer, pregnancy rate (PR), live-birth rate (LBR) and miscarriage rate (MR). The results showed no significant difference in the average number of days taking follicle stimulating hormone (FSH) for ovarian stimulation, the average amount of gonadotrophin used for stimulation, number of eggs collected and fertilisation rate. The pregnancy rate, miscarriage rate and the live-birth rate were not statistically different between all groups. However, in group E the miscarriage rate was significantly higher and the LBR was statistically lower compared with group B. We concluded that extreme BMI did not affect the super-ovulation outcome fertilisation rate and pregnancy rate. Women with a BMI > 35 had a higher miscarriage rate and hence a lower live-birth rate, but a reasonable pregnancy and live-birth rate can be achieved. For women with a BMI < 20 there was no difference in assisted reproduction treatment (ART) outcome and pregnancy outcome when compared with women with a normal BMI. This information should be used to advise patients who wish to embark on ART with extreme BMI.