For women planning ahead to having children, egg freezing is an exciting opportunity. It is useful for fertility decline due to age, medical conditions, or medical treatments. Whether to use egg freezing, and if so at what time, is not an easy decision.
Female fertility and age
While we’ve still got farther to go, women have more opportunities now than in previous generations. Many women confidently build a career throughout their twenties, and it’s common to start having children in your thirties. Unfortunately, female fertility hasn’t caught up to the changes in our society. Fertility stays pretty similar in the twenties and early thirties for most women, but it starts to decline in the mid to late thirties. Fertility ends in the early forties for most women, or 8 to 10 years before the menopause.
Whether it’s finding the right partner or a change in life plan, maybe you’ve realized that having kids while your fertility is still high may be a challenge. Egg freezing is one option to buy yourself more time.
Egg freezing is more effective when it is done by the mid thirties. Studies have found that eggs frozen under age 35 lead to better pregnancy rates than those frozen later. However, freezing eggs in the late 30s still increases your chances of becoming pregnant later.
Let’s suppose you will try to get pregnant in 7 years, and you are deciding whether to use egg freezing now. If you don’t get pregnant naturally after six months, you will either use your frozen eggs or traditional IVF.
A 2015 study in Fertility and Sterility used a mathematical model to look at this scenario. They found that egg freezing had higher pregnancy rates when done under age 34. However, the greatest increase in pregnancy rates compared to not freezing eggs was in the late thirties. Also, egg freezing was most cost-effective at age 37.
In addition to age, there are several tests of ovarian reserve, or ability for eggs to mature. Eggs are contained in the ovaries in protective follicles. A number of follicles begin to grow at the beginning of each menstrual cycle, and one or two typically reach ovulation. An antral follicle count (AFC) uses an ultrasound to measure how many eggs grow in the ovary. A test of anti-Mullerian hormone (AMH) measures a hormone level released by these developing antral follicles. Both tests can give you a better idea of how well your ovaries are currently functioning.
What about after the pill?
Age is not the only thing which affects the ovarian reserve. There are also medications and substances which can affect the ovaries, including the pill. While taking hormonal contraception, the ovaries become dormant and shrink in size. AMH and AFC tests also show lower ovarian reserve for users of the pill. After stopping the pill, it can take several months for the normal hormonal cycle to resume and the ovarian reserve to return to its baseline level. Waiting six months after stopping the pill may lead to a stronger response from the ovaries to the medications used during egg freezing.
Fertility preservation and cancer treatment
If you are going through cancer or are a survivor, your fertility can be another cause for concern. Chemotherapy and radiation treatment both reduce ovarian function and can increase the risk of birth defects. Ovarian reserve often improves one to two years after stopping chemotherapy, but not always.
If you are considering fertility preservation prior to cancer treatment, it may be important to complete the egg collection as quickly as possible. Ovarian stimulation is usually done during the early part of the menstrual cycle. However, it is also possible to do ovarian stimulation during the second half, or luteal phase, of the menstrual cycle. This method can allow egg or embryo freezing to be completed more quickly.
When to freeze eggs
Whether and when to use egg freezing is a personal decision. Egg freezing for age-related reasons has better pregnancy rates when it is done by age 35, but egg freezing after that still raises the chances of getting pregnant later. If you are using fertility preservation due to cancer or another fertility-threatening condition, there are alternate protocols which can speed up the egg freezing process.
Egg and embryo freezing offer additional options to allow women to become parents. Understanding how timing affects egg freezing can help you to use these options. For additional information read Should I Freeze Eggs or Embryos?