0834 More on outcomes after assisted reproduction

Quite recently, in summary 0830, the comment was made that it was not clear whether increased morbidity and mortality observed in products of assisted reproduction were due to the technologies utilized (ICSI, ZIFT, GIFT, cryopreservation of embryos, etc) or underlying pathological factors affecting the couple utilizing the technology. This question has been addressed and perhaps answered in a Norwegian study recently published in the Lancet. Whereas several meta-analyses have compared the outcomes after assisted reproduction to outcomes after spontaneous pregnancies, this latter one first assessed differences as previously done and then looked at the outcome for singleton pairs born to 2546 women who had both a spontaneous and an assisted pregnancy. 92% of the procedures involved fresh embryos, 22% involved ICSI, 39% were for a male infertility factor, 31% were for endometriosis or tubal factors, and 11% for ovulation dysfunction. Whereas the conventional comparison confirmed results of the abovementioned meta-analyses (2 x risk for preterm delivery, 3 x risk of weight <1500g, 50% higher risk of SGA) and showed higher perinatal mortality risk, the sibling-relationship comparisons showed no differences for birthweight, preterm delivery or growth retardation. In other words the increased risks appeared to be related to underlying factors in the couple seeking the technology rather than to the technology itself. Other studies have also commented on chromosomal abnormalities, but this aspect was not mentioned in the Norwegian study which nevertheless goes a long way to answering some of the questions. However others probably remain e.g. whether there are differences in outcome for frozen vs fresh embryos, or whether blastomere chromosomal screening carries a risk for lower pregnancy and live birth rates.

Read more:
Lancet 2008; 372: 737-43
J Obstet Gynaecol Can 2005; 27: 449-59
Hum Reprod 2008; 23: 1644-53