Prenatal Considerations After Oocyte Cryopreservation

Oocyte cryopreservation is a technology that has helped many women undergoing in-vitro fertilization. The technology allows for the extraction, freezing and storage of their oocytes for future fertilization and transfer. It allows women to fertilize only as many eggs as they need for an IVF cycle, without developing excess embryos and having to face the ethical challenge of disposing them.

The data on pregnancy rates for oocyte cryopreservation are encouraging. Fertilization and pregnancy rates for egg donation cycles using cryogenically preserved oocytes are similar to cycles using fresh eggs. Additionally, a recent compilation of research studies on egg freezing have found that babies born as a result of oocyte cryopreservation do not demonstrate an increased chance of having congenital abnormalities over their counterparts who were naturally conceived. Oocyte cryopreservation is still a technology that is advancing, but at the same time, it is no longer considered experimental.

During an IVF cycle that involves oocyte cryopreservation, one option to consider is Pre-implantation Genetic Diagnosis. Much like prenatal diagnosis, PGD is the genetic profiling of embryos prior to implantation. It can be used to screen for a specific genetic disease, such as single-gene disorders, and even X-linked and mitochondrial disorders. By transferring only the most healthy and viable embryos to the uterus, it eliminates the chances of selective termination of pregnancy in the future, and increases the chance of giving birth to a healthy baby.

PGD also allows for the diagnosis of late-onset diseases and predisposition to cancer, as well as the presence of disease or disability such as deafness, which is particularly useful if either the mother or father has a family history of relevant illnesses.

For women of advancing maternal age (over 35 years of age) or who have undergone repeated failed IVF cycles, PGP is largely justified. The screening for detection of chromosomal abnormalities such as aneuploidy, chromosomal inversions and deletions can help shed some light on why previous IVF cycles had failed.

After implantation, there are also common prenatal screening and diagnosis that are important components of prenatal care. This includes first trimester exams such as Fetal Cells in Maternal Blood, and Cell-free fetal DNA in Maternal Blood tests, which are both noninvasive methods in the diagnosis of aneuploidy and such diseases as Down Syndrome, Edwards Syndrome, and Patau Syndrome.

Prenatal examinations are also important later in pregnancy. During the second trimester, less invasive screening exams such as maternal serum alpha-fetoprotein and beta-HCG can be used to screen for other deformities such as neural tube defects. Also, during the third trimester, fetal well being can also be monitored using the Non-stress test, which monitors the frequency of accelerations and decelerations of fetal heart rate.