The quick answer is – once you have decided that you would like to preserve your fertility – the sooner the better.

Age matters.

When it comes to fertility, age matters. We are born with all the eggs we’re ever going to have – about 2 million. By the time we reach our first period, we’re already down to 300,000-400,000 eggs (totally unfair, we know). From there – whether we’re on birth control and actually bleed or not – we lose up to 1,000 eggs every month.

Quality is just as important as quantity.

As we get older, the quantity of our eggs declines, but the quality declines too. Poor egg quality could result in a higher rate of miscarriage or having a child with a genetic abnormality. Doctors typically point to 35 as the age at which fertility declines. But, this isn’t just a switch that turns off one day. As we age, our eggs age with us. In addition, 1 in 20 women experiences premature low ovarian reserve under the age of 35.

Success rates decline with age.

We’ve heard a lot of confusion in the media and from our own patients about the success rates of egg freezing. Does egg freezing guarantee a successful pregnancy and birth? Does going through egg freezing guarantee you will have any eggs to freeze at all? Can I assume the success rates I’ve read about apply to me? The answer to all of these questions is no.

As egg quantity diminishes, the quality does too, and both of these impact success rates. The rate of egg decline varies tremendously among women, but usually increases in the mid-to-late 30s. For people who are not ready for pregnancy, egg freezing is a choice that may give them an increased chance of pregnancy at a later time. The key is that these chances vary based on each patient’s age and clinical history. 

At Kindbody, we believe that every person should understand their own fertility as well as their statistical chances of success so they can make her own decisions about how to achieve their reproductive goals. Our patients use our calculators found on the Kindbody Portal to help bring clarity to their personal success rates. 

In a Modern Love column in the New York Times, the author says, “When I froze my eggs, I didn’t understand [egg freezing] has only a 2 to 4 percent success rate per thawed egg, according to my clinic, meaning more likely than not, my eggs would fail me.” The truth is, success rates vary based on a lot of factors, but they vary most dramatically by age. We used our calculator tool in the portal, which uses one of the most reputable research studies in the industry to dig into this number. Here’s a sampling of the likelihood of 1 live baby with 20 eggs frozen:

Age 34: 90%

Age 37: 75%

Age 42: 37%

What these data tells us is that egg freezing is not a guarantee, and you certainly need more than 1 egg in order to have a reasonable chance of success. 

How many eggs can I expect from a cycle of egg freezing?

This answer also varies dramatically. Our patients use our calculator (which uses this other commonly used research study) to input Age, AMH (blood test), and Antral Follicle Count (ultrasound exam) to get a better idea. For a 33 year old with a “normal” AMH and Antral Follicle Count, they can generally expect north of 10 eggs retrieved from a single cycle which, using the data above, would give them a 69% chance of being able to use those eggs for 1 live baby. Using this data, they may choose to do an additional cycle to increase those chances. That’s up to them.

Success rates are a very important consideration in any fertility treatment decision, and we recommend understanding how they apply to you. We believe this data is empowering and not scary, because the earlier you can make your reproductive plan the more options you’ll have. As always, if you have any questions at all, we’re here to help.

Join one of our events to learn more


  • July 6th at 6:30pm EST with Dr. Rinku Mehta
  • July 20th at 6:30pm EST with Dr. Lauren Sundheimer
  • August 3rd at 6:30pm EST with Dr. Rachel Cohen


Learn more about egg freezing

Schedule an Egg Freezing Assessment at a Kindbody clinic.


Dr. Lynn Westphal
Dr. Lynn Westphal
Dr. Lynn Marie Westphal, M.D., FACOG, and Kindbody's Chief Medical Officer graduated summa cum laude from Lawrence University, earned her M.D. degree at Stanford University, and did her residency training in obstetrics and gynecology at UCLA and Stanford University. She did a fellowship in molecular biology at Stanford University and completed her fellowship in Reproductive Endocrinology and Infertility (REI) at UCSF. Dr. Westphal joined the full-time faculty at Stanford University in 1998 and was a Professor in the Department of Gynecology and Obstetrics, Director of the Fertility Preservation Program, Director of the Third Party Reproduction Program, and Director of the REI Fellowship. Her interest in fertility preservation for cancer survivors led her to set up one of the first oocyte cryopreservation programs in the country. She has held numerous national leadership positions and was the President of the Fertility Preservation Special Interest Group of the American Society of Reproductive Medicine from 2008-2009. She was the Director of Women’s Health at Stanford from 2005-2012. In 2012, she co-founded the Stanford Center for Health Research on Women and Sex Differences in Medicine (WSDM) and served as co-director of the program for two years.