Materno-fetal immunogenetic disparity: the biological basis for in vitro fertilization treatment in patients with unexplained recurrent abortion?

Problem: The majority of women with recurrent miscarriage have no discernible cause but it has been postulated that immunologic aberrations may be the cause in most of such cases. Also, it has been stressed that deliberate modification of the maternal host defense system can improve the chances of success. We tested the hypothesis that it is possible to potentiate maternal immune functions so as to improve reproductive performance by replacing several embryos into the uterus, thus favoring the recognition of fetal antigens.
Method of Study: A total of 57 couples with three or more (mean 5.52; range 3-12) consecutive first-trimester spontaneous clinical abortions of unknown etiology were treated with in vitro fertilization (IVF) and embryo transfer for a total of 84 cycles. Patients underwent IVF after combined gonadotropin-releasing hormone agonist/gonadotropin treatment for ovarian stimulation, and up to four embryos were replaced into the uterus.
Results: There were 32 pregnancies (three of them after frozen-thawed embryo transfers) and 26 (81%) of them were viable gestations. Overall, patients had a previous obstetric history of 315 pregnancy losses and 15 live-born babies. Thus, the probability of having a live baby before treatment was 4.54% (95% CI, 2.78-7.36) a figure significantly lower (P < 0.0001) than that observed under IVF treatment (81%; 95% CI, 64.53-91.01). None of selected variables potentially related with the outcome of pregnancy after IVF and embryo transfer in recurrent aborters (including pre-implantation genetic diagnosis) was found to be associated with miscarriage.
Conclusions: This study shows that replacement of several embryos after IVF is a useful treatment in the prevention of unexplained recurrent spontaneous abortion thus providing further evidence for immunologically modifiable pregnancy loss.