Egg freezing, explained.

author : Jane Riccobono

art : Cari Vander Yacht

It’s presented as a magic bullet for career-minded women: freeze your eggs now, figure out kids later. First offered in the 1990s to cancer patients undergoing radiation therapy, it’s now a draw for healthy women worried about age-related infertility.

And it’s on the rise. According to the Society for Assisted Reproductive Technology, the number of women freezing their eggs climbed 24 percent between 2016 and 2017. Employers have caught on, too, especially in the tech sector. Facebook, Apple, Google, and a host of other companies offer to cover the $15,000-plus price tag for their employees.

This growing industry, part of the $17 billion fertility market, rests on the idea that as women age, their eggs deteriorate, so healthy ones need to be preserved ASAP. Freezing eggs, the logic goes, gives a woman a better chance of having her own biological child at a later age through in vitro fertilization (IVF). Yet a closer look at the research presents a more complex view.

Foundational studies that show a decline in fertility after age 35 are based on populations from 300 years ago, and we’re not even sure the women in them were trying to conceive. When we look at women today, the data suggests this fertility decline might be overhyped. According to the UK’s National Institute for Health and Care Excellence, women under age 40 have an 80 percent chance of becoming pregnant after one year of trying to conceive and a 90 percent chance after two years. Between ages 40 and 44, about 30 percent of women experience infertility, according to the CDC. Risk of miscarriage goes up, but only slightly. Down Syndrome, the most common chromosomal abnormality, carries a 0.1 percent chance for 30-year-old mothers. By 40, it’s still just 1.1 percent.

But what if you’re sure you don’t want kids until you’re 40, or want extra reassurance about future reproductive options? Egg freezing is still worth considering—as long as you consider it fully.

Each cycle involves about two weeks of frequent office visits and self-administered hormone injections, which can cause bloating and fatigue, followed by a 20-minute surgical procedure to remove the eggs. During the procedure, which is done under anesthesia, a thin needle pierces the vaginal wall into the ovaries and retrieves the eggs. Depending on the number and quality of eggs retrieved, the cycle may need to be repeated. Each process costs about $15,000. Given the added costs of additional cycles and storage, the average person ends up paying between $30,000 and $40,000, which is rarely covered by insurance.

Researchers aren’t totally sure how long frozen eggs stay viable. One study showed no significant difference in pregnancy success rates after four years of storage, and in 2014 a baby was born using an egg that had been stored for 14 years. Whenever a woman decides it’s time to thaw her eggs, the process works the same way as in IVF. The egg is fertilized with sperm, and the resulting embryo is placed into the uterus with a thin catheter that enters through the cervix.

The likelihood of having a successful pregnancy depends on how many eggs are frozen and how old the person freezing them is. Fertility experts at Boston’s Brigham and Women’s Hospital suggest that a woman under age 35 who freezes 15 eggs has an 85 percent chance of having a baby with one of those eggs; at 40, it goes down to 42 percent.

The process is still quite new, which means there isn’t a lot of data on health outcomes for mothers or babies. The data we do have shows that babies conceived using frozen eggs have the same rate of chromosomal abnormalities as those conceived through IVF with fresh eggs. There is no research yet comparing births from frozen eggs to babies conceived naturally. The risks to the pregnancy itself are thought to be similar to those of IVF: a higher risk of a premature or low birth weight baby, and higher rates of pregnancy complications like high blood pressure and Caesarean section.

Rather than a straight- forward solution, egg freezing is a complex process full of research holes about age and fertility. We still don’t know enough about how effective the process is. Time and data can fill in the missing pieces and differentiate between myth and fact, but until then, it’s not a given that egg freezing is for everyone. Period.