Elective single embryo transfer yields good delivery rates in oocyte donation

BACKGROUND: High pregnancy rates have been noted after oocyte donation (OD). Multiple pregnancies should be avoided, because oocyte recipients have an increased risk of obstetric complications. METHODS: We analysed our OD results from 2000±2001 when elective single embryo transfer (eSET) was introduced as a recommended policy for all recipients if at least one good quality embryo was available. The results were compared with those achieved in 1998±1999, when usually two embryos were transferred (double embryo transfer, DET). Between 1998 and 2001, 100 healthy women donated oocytes and 135 fresh embryo transfers were carried out. The mean age of the donors was 31 years and that of the recipient women was 35 years. RESULTS: The proportion of eSET of all OD transfers was 17.1 % in 1998±1999 and 61.0 % in 2000±2001. There was no statistically signi®cant difference in clinical pregnancy (36.8 versus 45.8%) and delivery rates (31.6 versus 33.9%) per embryo transfer between the two time periods. The proportion of twins declined from 29 % (1998±1999) to 10 % (2000± 2001). The delivery rate was similar after eSET and DET (32.6 versus 32.1 % respectively). CONCLUSIONS: By increasing the proportion of eSETs it is possible to reduce the number of twins without affecting delivery rates in oocyte recipients. Key words: multiples/oocyte donation/pregnancy rate/recipients/single embry