Scientists from China have found that freezing human embryos for one to two years leads to a significant decline in the chance of it developing into a baby.
The experts looked at more than 24,000 cases where women opted for egg freezing and found that embryos stored for less than three months had better chances of developing into a successful pregnancy. Moreover, the researchers found that the storage process had no ill effects on the fetus' health.
In the study, the research team found that the clinical pregnancy rate significantly fell from 56 to 26 percent. They came up with these percentages after comparing embryos that had been kept in storage for up to three months with those frozen from between 12 and 24 months.
In the same manner, they found that the live birth rate also declined from 47 to 26 percent between the two different storage spans. Additionally, the researchers also looked at a subset of younger women to make sure that age was not a factor for the results.
They found that more than 7,000 women aged 36 or younger had infertility that was caused by damaged or blocked fallopian tubes, and not their age.
Based on their paper's results, the team have recommended that clinicians should consider the consequence of storage duration before deciding how many embryos to store and freeze.
Dr. Qianqian Zhu, one of the authors of the study, said that it is especially crucial for cancer patients who may have their ovaries damaged by cancer therapies. Also, it might have implications on those who have to postpone fertility until they have been cured of their disease.
The findings of the study were published in the journal Human Reproduction on June 23, 2020.
Egg Freezing Through Vitrification
Vitrification involves the process of briefly putting embryos in a solution that dehydrates them before they are quickly frozen into a glass-like state using liquid nitrogen.
Technicians use chemicals that inhibit ice crystals from forming on the embryos as they are being prepared to be frozen for storage.
Vitrification is a simple, fast and low-cost technique that has become popular around the world. When the embryos are needed, the process is then reversed.
However, many are still concerned about the safety of the procedure. Furthermore, some experts have suggested the method is unsafe for the embryo. Some also fear that it could lead to complications, such as low or high birth-weights and other defects.
How Does In Vitro Fertilization Work?
In vitro fertilization (IVF) is the process of fertilizing a human egg from outside of the body, and then implanting the early embryo in a woman's uterus. Many couples consider IVF when they cannot conceive on their own.
According to Dr. Megan Link, a reproductive health expert from the University of Utah Health, in vitro fertilization is also used to prevent genetic diseases that might concern parents. The procedure has become rather routine, and complications are acutely rare.
Although not every IVF procedure results in a pregnancy, it has become a feasible option for those who cannot become pregnant through natural means.
According to the University of Utah Health, the in vitro fertilization process involves five steps. First is the stimulation of the ovaries. Next is the retrieval of the egg and sperm cells. Then comes the fertilization of the eggs. Finally, the embryo will then be transferred to the uterus through a catheter.
Most women worry about the in vitro fertilization process hurting. Experts say that some discomfort may be expected, although extreme pain is not so likely.