Objectives: To investigate the effects of single blastocyst transfer (SBT) on live birth and multiple pregnancy in women undergoing in vitro fertilisation (IVF).
Design: Descriptive cohort study.
Setting: A London private IVF/postgraduate training unit.
Sample: A total of 700 fresh and 102 frozen blastocyst cycles performed between January 2005 and December 2006.
Methods: Young women aged 25-37 years and those aged 38-43 years were further divided into those who had SBT and those who received two blastocysts (double blastocyst transfer [DBT]). Live birth and multiple pregnancy rates were compared between groups. Cumulative live birth was compared between women who had DBT and those who received a SBT followed by a frozen blastocyst if the fresh cycle was unsuccessful.
Main outcome measures: Live birth rate, cumulative live birth rate, multiple pregnancy rate, uptake of SBT.
Results: Among women aged 25-37 years, live birth rate following SBT was 59.0 versus 60.7% following DBT. The twin pregnancy rate in this group was 2.3 and 47.6% respectively. For women aged 38-43 years, live birth following SBT was 29.4% and multiple pregnancy rate was 33.3%. DBT in older women gave a higher live birth rate (44.3%) and a multiple pregnancy rate of 36.4%. Cumulative live birth following SBT in women aged 25-37 years was 72.8% versus 60.5% following DBT. Among the women aged 38-43 years, cumulative live birth was higher (63.3%) following DBT versus 28.6% following SBT.
Conclusion: Single blastocyst transfer followed by transfer of a frozen blastocyst if the preceding fresh cycle was unsuccessful resulted in a better cumulative live birth and lower twin pregnancy in young women. In older women, two fresh blastocysts gave better results than one fresh followed by a frozen cycle. Older women should have the option of replacing two fresh blastocysts as this optimises their chances of taking home a baby.