ABSTRACT
BACKGROUND: More than one embryo is normally transferred per cycle to increase the probability for pregnancy after assisted reproduction. This has led to a high rate of multiple pregnancies, which increases the risk of complications for the mother and child. MATERIAL AND METHODS: 2765 assisted reproduction cycles were performed in the Fertility Unit at St. Olav's Hospital, Trondheim from 2002 to 2005. During this period we changed our cryopreservation programme and introduced elective single embryo transfer in an increasing number of women. RESULTS AND INTERPRETATION: From 2002 to 2005 the multiple pregnancy rate following transfer of fresh embryos decreased from 36 to 8 %. 75 % of all women who received hormone stimulated treatment with transfer of fresh embryos in 2005, had one embryo transferred. The proportion of cycles with surplus embryos available for cryopreservation increased from 27 % in 2002 to 69 % in 2005. Despite a slight reduction in the number of pregnancies during this period the pregnancy rate per oocyte recovery has remained stable. The improvement of our freezing/thawing routines has been crucial for improving treatment at the same time as we have reduced the fraction of multiple pregnancies. This implies less constraint on the couple and reduced costs for society. Lack of refund and valuation of freezing/thawing of embryos renders a continued optimal medical practice difficult.
