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Oocyte cryopreservation, commonly known as egg freezing, has become more popular among women who desire to postpone childbearing. We talked to Dr. Frank Nawroth about how it works and whether it entails any risks.
DW: How does egg freezing work?
Prof. Dr. Frank Nawroth: In general, the patient self-administers a subcutaneous injection of hormones that stimulates her ovaries to produce eggs, for a period of ten days. Two ultrasound examinations will take place during this period to see how egg production is progressing. After about ten days, egg cells will be harvested with the patient under anesthesia. This takes around five minutes. A vaginal ultrasound probe is used to guide a needle through the vaginal wall and into the ovary. Once the needle is inside the follicle, suction is used to aspirate the fluid and egg into a test tube. Eggs that are fully mature are then frozen.
At what age do women stand good chances of conceiving with frozen egg cells?
“Good chances” is a broad term. Ideally, the patient would be in her late 20s or early 30s. In my practice, we take the patient’s age into account when we advise her and we don’t treat patients older than 38 or 39. We don’t freeze the eggs of older patients as the likelihood of conception is much lower and we cannot justify raising the patient’s hopes. So ideally, the patient will be in her late 20s. But for the time being, no women this age are coming to us.
How long can the eggs remain frozen for?
According to current information, time is not a factor. But this also applies to fertilized eggs, sperm and tissue. What’s important is that the eggs survive the freezing and thawing process. How long they are stored for is not an issue. Years, days – it doesn’t matter.
Does freezing eggs pose any risks to the patient?
The risks are minimal. There is a one percent risk that harvesting the eggs can cause an infection or a hemorrhage; there is also a one percent risk that over stimulation of the ovaries can lead to stomach ache.
Are there any risks for the baby?
We can assume that there is no increased risk because we have been freezing eggs for thirty years. We know that in the case of one thousand babies born from frozen eggs, the risks are not increased. There would be no logical explanation for why they should be higher in the case of unfertilized eggs than in fertilized eggs. We assume that there is no increased risk for the child. Of course we need to be careful with a 50-year-old patient. That would be a high-risk pregnancy, so should be thought through.
Frank Nawroth is a gynaecologist and obstetrics specialized in reproductive endocrinology and infertility. He works at the amedes experts fertility center in Hamburg. http://www.amedes-experts-hamburg.de
Interview: Dorothee Grüner