In vitro fertilization can be risky and costly. Implanting multiple embryos to increase the odds of birth often leads to multiple babies. But a study by Finnish researchers suggests a better way to do things. Transferring a single fresh embryo to the womb, followed by transfers of individual thawed embryos in later fertility cycles if necessary, may be as effective in achieving pregnancy as implanting multiple embryos at once. The study compared outcomes from two periods at a fertility clinic: one during which double-embryo transfer was used more than 95% of the time and another in which 46% of women opted for single-embryo. In both periods, 90% delivered babies within the first four treatment cycles. The study also considered the cumulative success rate for all embryos created from a single harvest of eggs including those that had been frozen. For each ovum pickup, the overall pregnancy rate was 38% among women who had elective single-embryo transfers and 33% among those who had multiples.