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Egg freezing is on my mind. At 36, I’m at an age when many of my friends have had babies, and the few who haven’t are weighing up their options. If they plan on having children at some point in the future, should they be freezing their eggs now?

It is an incredibly personal decision, and it’s not always an easy one. While egg freezing is often sold as a fertility insurance policy—“eggsurance”—we’re still not entirely sure how successful the procedure is likely to be for any individual person, or how success rates vary by age.

We do know that it is expensive—we’re talking potentially tens of thousands of dollars for hormonal treatments, egg collection procedures, and years of cryopreservation. And we know that it’s not without risks.

Around 16% of women who freeze their eggs end up regretting their decision. So researchers are now working on tools to help people considering egg freezing make the right decision for them.

People choose to freeze their eggs for all sorts of reasons. But the women who do so for social reasons tend to fall into one of two groups, says Zeynep Gurtin, a sociologist of women’s health at University College London.

The first group is made up of women in their 20s or early 30s. These women know they want to have children someday—perhaps in around five years’ time—but they’re not ready yet. They might be studying or training for their career, or traveling, says Gurtin. “They’re [egg freezing] as a proactive measure,” she says.

The second group includes women in their late 30s or 40s, who want to have children but aren’t in a position to do so, usually because they aren’t in a relationship with someone who feels ready. “Many of those women say they had hoped to be mothers by now,” says Gurtin. They know their fertility window is closing, and they want to give themselves the best chance of pregnancy in the near fu...