For patients with recurrent pregnancy loss

Preimplantation genetic testing for chromosomal structural rearrangement

• （6）Chromosomal translocation in either partner
• INDEX
• （8）Congenital uterine anomaly

Preimplantation genetic testing for chromosomal structural rearrangement (PGT-SR) prevents miscarriage, but it has not been proven that PGT-SR improves the live birth rate in patients with RPL caused by a translocation.

PGT-SR was first reported in 1998, and then came into use in Japan in 2006. This technology is designed to take out some of the fertilized embryos obtained through in vitro fertilization and to transfer (IVF-ET) only the balanced embryos to prevent miscarriage. In Japan, PGT for hereditary diseases is being deliberated carefully due to the ethical criticism that it could lead to a dominant philosophy. The Japan Society of Obstetrics and Gynecology (JSOG) has ruled that only serious genetic diseases can be approved after deliberation on a case-by-case basis.

The ethical criticisms are summarized as follows.

• It is a waste of life.
• It leads to eugenics.
• IVF-ET is performed on women who are able to conceive naturally.
• The long-term safety of the baby is unknown.

According to the European Society for Human Reproduction ESHRE PGD Consortium, the standard weight of babies born with a pre-implantation diagnosis is 3225 grams, and congenital anomalies were found in 5.8% (47/813), which is similar to the frequency reported by the ICSI. The development of a child at the age of 6 years is similar to that of a child from a natural pregnancy, but it is not yet known if the child will be safe in the long run.

As mentioned earlier, the success rate of a spontaneous first pregnancy after diagnosis is 31.9%-65%. While it seems theoretically possible that a pre-implantation diagnosis could slightly reduce the likelihood of a miscarriages, there are no reported randomized trials that prove that people who are unable to give birth will be able to do so.
In Japan as well, preimplantation diagnosis for repeated miscarriages caused by chromosomal balanced translocations was initiated in December 2006. Nagoya City University and St. Mother's Clinic of Obstetrics and Gynecology (Kitakyushu City, Japan) reported for the first time anywhere the birth rates of patients with RPL caused by chromosomal translocations who opted for PGT-SR and spontaneous pregnancy (19). Because the age of the patients who requested a PGT-SR was higher than average, we examined the birth rates and other data of 37 patients with RPL due to a balanced translocation who were under 35 years of age, as well as those of 52 patients who chose to have a natural pregnancy, until July 2014.
The results showed that the birth rate of the first PGT-SR patients was rather worse than that of patients with a natural pregnancy, but there was no difference in the cumulative birth rate (67.6% and 65.4%, Table 6). The pre-conception time was also similar (12.4 and 11.4 months). However, miscarriages were significantly reduced in the PGT-SR group (mean 0.24 and 0.58 miscarriages, respectively) and subsequent failure to conceive was more frequent (18.9% vs. 3.8%).
Nine out of 37 (24.3%) of the women over 35 years of age who opted for PGT-SR were able to give birth. Comparisons could not be made for those over 35 years of age because of the small number of spontaneous pregnancies. This was not a randomized trial and there may have been a bias between the two groups. In addition, the number of cases was limited.
The ESHRE RPL guideline cites this article as a reference and suggests that genetic counseling should be used to explain both the advantages and disadvantages of PGT-SR in cases of chromosomal abnormalities in either partner of a couple.