COPENHAGEN — The higher rate of obstetric complications documented in donor oocyte pregnancies is confined to those pregnancies in which the oocyte donor is not related to the recipient, according to Korean researchers.
In fact, pregnancies achieved through in vitro fertilization procedures involving oocytes donated by a sibling have a complication rate similar to that of in vitro fertilization pregnancies that do not involve donor oocytes, reported S.H. Cha, M.D., in a study that was directed by M.K. Koong, M.D., from Samsung Cheil Hospital, Sungkyunkwan University, Seoul.
This is the first report linking different degrees of oocyte allogenicity to obstetric complications, suggesting that this phenomenon could be due to immunologic factors, Dr. Cha said during the annual meeting of the European Society for Human Reproduction and Embryology.
It has been well documented that pregnancies achieved using donor oocytes demonstrate increased rates of pregnancy-induced hypertension and first-trimester bleeding, Dr. Cha said. Possible explanations for these findings include primiparity, the higher rate of multiple pregnancies, and the increased maternal age of this obstetric population.
Dr. Cha's study compared 61 pregnancies resulting from oocyte donation and 127 pregnancies from standard, nondonor in vitro fertilization (controls). Of the donor pregnancies, 36 involved oocytes from siblings and 25 involved oocytes from nonsiblings.
As expected, the donor group had a much higher rate of early pregnancy loss (34% vs. 13%), second-trimester bleeding (13% vs. 1%), and pregnancy-induced hypertension (12.5% vs. 4%), compared with the controls.
But when the donor group was subdivided into sibling and nonsibling donors, the complications were largely concentrated in the nonsibling donor group. The sibling donor group showed a complication rate that was only slightly (and not statistically significantly) higher than that of the controls, Dr. Cha said. (See table.)
“These data suggest that PIH [pregnancy-induced hypertension] appears to occur more often in pregnancies following oocyte donation from immunologically unrelated donors. Therefore, women who become pregnant after oocyte donation from immunologically unrelated donors should be considered as high risk,” she noted.