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6 Things You Didn't Know About Egg Freezing

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Last week, singer-songwriter Sophie B. Hawkins ("Damn, I Wish I Was Your Lover") announced that she is pregnant—and due any day now—with a baby conceived via eggs she froze nearly 20 years ago. Hawkins is 50 and has a 6-year-old son named Dashiell.

Besides the interesting point she made on the TODAY Show about wanting to give Dashiell a playmate ("I had, you know, spoken to a fertility doctor in New York. And she said, 'You're old.' And I said, 'That's the point.' My son has an old mother. Why can't I give him somebody young to be his family for the rest of his life."), how fascinating is it that Hawkins not only had the foresight to freeze her eggs back when she was 31 (most women wait until their late 30s), but that those eggs were able to be thawed and create life two decades later?

I spoke with reproductive endocrinologist Jane Frederick, MD, Infertility and Medical Director of HRC Fertility in Orange County, Calif., who gave me the dirt on exactly how this is possible …and why Hawkins was smart to freeze early. We came up with the following six things most women don't know about egg freezing:

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1. A woman is born with all of the eggs she will produce throughout her lifetime

Actually, our ovaries contain over 6 million eggs when we're 20 weeks in utero. By the time we're born, it drops to 350,000 eggs. During puberty, at age 12, our stash drops to 200,000. (The reason? Just as we shed skin and hair, we lose eggs, too.) And once we hit age 37, a sharp decline begins, accelerating by 40. This is why older moms are more prone to delivering babies with chromosomal issues; the eggs that contributed their genetic material have been sitting around for a fairly long time (versus, say, a 20-year-old.)

2. Babies created from frozen eggs are just as healthy as babies conceived the "normal" way

"Even if your eggs have been frozen for a long time, you can still have a healthy kid," Frederick says. "There's no increased rate of birth defects just because an egg or embryo was frozen."

3. It's not the same as freezing your leftover chicken

Once they're retrieved, eggs are stored in liquid nitrogen at a temperature of minus-300 degrees Celsius. "The egg is a big cell filled with fluid," Frederick explains. "We dehydrate it, remove the fluid, the membrane shrinks down, and then it is plunged into nitrogen." Doctors used to do this slowly, over the course of hours, but they now know that a rapid freeze produces better odds of thawing and surviving at a later date. (For that very reason, Frederick is pleasantly surprised that Hawkins was able to conceive; the fast freeze technique wasn't being used when she froze.)

4. Egg freezing was first developed for women undergoing cancer treatment as a means of preserving their fertility

It's only in the relative recent past that it's begun gaining in popularity among healthy women in their 30s and early 40s. Now some companies (usually tech-based) are even covering the costs.

5. Egg freezing is not a foolproof way to get pregnant

Instead of thinking, "My eggs are frozen, I'm good to go, no rush to start my family," Frederick recommends viewing them as insurance backup. Besides, lets say you freeze your eggs and then, a few years later, decide to start trying to conceive; your doctor will likely encourage you to start trying the old-fashioned way. If a patient is between 35-40, Frederick will suggest she try on her own for six months before having a fertility workup done. (Once you hit 40, though, doctors typically drop the waiting period.)

RELATED: To the Parents Raising My Eggs

6. Having eggs chillin' in the freezer is no absolute guarantee of pregnancy

According to the American Society for Reproductive Medicine, the chance that a single frozen egg will produce a live birth is about 2 to 12 percent. Thankfully, most women don't freeze only one egg; you want a few dozen to maximize your odds. Frederick says that in her practice, women who froze their eggs before age 35 ultimately have about a 50 percent chance of conceiving and carrying to term. Over 40 when you froze? That percentage drops to 25 percent. All clinics are different, though, so make sure to investigate yours thoroughly.

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