A comparison between multiple and single pregnancies obtained by in-vitro fertilization.

Thirty-eight single and 10 multiple pregnancies obtained after in-vitro fertilization were compared. In the group of multiple gestations, maternal age was lower and the amounts of ovulatory drugs given were significantly smaller than in relation to single pregnancies. All multiple pregnancies arose from triple embryo transfers and the embryos from this group exhibited significantly higher vitality scores. In both groups, plasma levels of oestradiol and progesterone followed the same pattern until day 8 after oocyte retrieval. Following implantation, the secretion of these hormones increased more rapidly in multiple pregnancies pointing at greater luteal activity in this group. HCG levels became significantly higher in multiple gestation on day 25 after oocyte collection. Echographic examination showed that, compared to normal pregnancy, growth in both groups of IVF conceptuses was initially retarded but caught up with normal evolution at approximately 30 days after egg retrieval. The need for adjusting the number of embryos transferred not only to expected success rates but also to the risk of high rank multiples is emphasized.