Our website uses Cookies. By continuing to use our site, you are agreeing to our Cookies Policy

Join our IVF info session on 05/02 and receive a $250 IVF consult LEARN MORE

Medical Factors

How does egg freezing work?

Cryopreservation places cells into a “glass-like state” where all biologic processes stop by rapidly changing the temperature to -196°C using liquid nitrogen. The cell can be maintained in this state for years without aging. Your doctor will determine a protocol that’s right for you. Bioidentical hormones are used to help the ovaries produce multiple eggs from multiple follicles. These eggs are then retrieved from your body and cryopreserved a few hours later.


What causes the decline in fertility?

A woman’s age at the time an egg is released is the single most important factor affecting fertility. Beginning in your 20s, there’s a gradual decline in the ability to become pregnant. Around age 35, fertility begins to decline more rapidly. Freezing your eggs gives you more options for the future by preserving your eggs (and their current quality) today.

Two factors lead to this decline: fewer and lower quality eggs.

Fewer: eggs, unlike sperm, are only produced before a baby is born. At birth, a female is born with 1-2 million eggs. These eggs are called primordial follicles and are suspended in a state of partial maturity that is not completed until ovulation (often decades later). They are gradually released over the next 50 years. Total eggs remaining in the ovaries:
At birth: ~1-2 million
At puberty: ~400-500,000
At age 35: ~25,000

Quality: While the total number of eggs available declines daily, egg quality also starts to drop as the long term effects of minor environmental damage add up. The cumulative effects of aging become apparent by your mid 30s, when eggs are more likely to produce chromosomal errors (called “aneuploidy”), leading to miscarriages and infertility.

How does egg freezing help?

Egg freezing (or ‘oocyte cryopreservation’) stops eggs from aging by placing them into a state of ‘biologic pause’ (vitrification) until a woman is ready to get pregnant. The health of those eggs is safely maintained at the age and time they were frozen.

What about my uterus? Even if I freeze my eggs, isn’t my womb aging too?

Your uterus is amazing and is not affected by age the way eggs are. In fact, many women have conceived after menopause with donor eggs and a little estrogen to support the uterus.

Why is it so new?

Turns out, cryopreservation of eggs takes lots of expertise. Prior to freezing, the embryologist safely replaces all the water from an egg with cryoprotectants. Your embryologist then rapidly moves the egg cell through different solutions and then must freeze (vitrify) the eggs in 1 microliter of water (that is 1/1000 of a milliliter). The whole process is still done by hand, and the best protocols are still considered trade secrets. At Spring, we’re proud to work with the best embryologists who have the best equipment to innovate and improve existing protocols.

When should I freeze my eggs?

Everyone has different plans, and when egg freezing fits for one person might not be the right time for another. There’s no clear answer and this is a personal choice, but we know that eggs are healthiest when women are in their mid 20’s. This is when women have the most follicles and eggs free of chromosomal abnormalities. This is why most egg donor programs only work with women between the ages of 21 to 30.
Everyone has different reproductive horizons: some women go through menopause at 51 while others might have their last menses at 41. Freezing eggs can seem expensive for younger women who are earlier in their careers, but the process is actually less expensive when you are younger. Older women commonly need to do more cycles at a greater expense because they produce fewer eggs and require more medication.

So what if I’m 25? 30? 35? 40?

The best way to decide on whether and when to freeze your eggs is to have an initial consult. During this 60 minute appointment, we’ll perform a pelvic ultrasound and blood test to assess your ovarian function. Then we can discuss your treatment plan. The plan we choose depends on your unique situation. We want to understand your goals and concerns, and provide the best option for you.

How many eggs will I be able to freeze?

This all depends on your “ovarian reserve” (or the number of eggs present in the ovaries at any given time). Younger women usually have more follicles (immature eggs) and can retrieve and preserve more good quality, mature eggs per stimulation cycle. At your first consult, a pelvic ultrasound with an antral follicle count gives us a good idea of how many to expect.

Will I have to do multiple cycles?

Again, this all depends on your age and antral follicle count, as well as your family-building goals. Some women retrieve all the eggs they need in one cycle. Others may require several cycles, especially if they think they might like to have multiple children when they’re ready. Your initial consult is the best way to get started. We’ll assess your ovarian reserve, and discuss your options. Together we’ll make a plan.

How long can eggs be frozen?

Since egg freezing is a relatively new procedure, there isn’t a lot of data on the long term storage of frozen eggs. Reports comparing eggs frozen for four years with those frozen for short durations do not show any adverse effects of longer storage. Animal studies and human embryos have shown good outcomes after over 20 years of being cryopreserved. So while we can never say with complete certainty, it seems that storage for up to 20 years can be both safe and effective.

Is it safe for my future baby?

Yes. Studies of over 5,000 children born from thawed/frozen eggs show no increased risk for congenital abnormalities or adverse pregnancy outcomes.

This is San Francisco, what if there’s an earthquake?

Your eggs are safe at Spring. Our building was constructed to meet or exceed modern seismic standards, including all California and local guidelines, and will easily withstand any anticipated tremors or quakes in the area.
In the event of a large and prolonged power outage, all of our critical equipment is connected to a large Uninterruptible Power Supply (UPS) system (with over 16,000 pounds of batteries!) located on site, so we are never subject to a power surge or failure. Our UPS immediately sends us an emergency alert and can maintain power for over 8 hours, allowing plenty of time to fire up our backup generator, which is also regularly maintained and tested. As with everything at Spring, we have backup systems for our backup systems, and we take nothing for granted.

Is there an age limit on egg freezing?

At Spring, we believe it’s our responsibility to provide our patients with transparent and realistic expectations as to the likelihood that freezing your eggs will result in a successful future pregnancy. The oldest reported woman to successfully freeze and warm an egg that resulted in a live birth was 42 at the time she froze her eggs.  We want to leave room to “move the needle” and advance the field, so we will allow well-counseled women to freeze their eggs through age 43 (understanding that no 43 year old women have successfully frozen eggs that resulted in a live birth).  For women aged 44 and up, the probability of having a baby from frozen eggs is too low and the success rate unproven, so we will not freeze eggs at this time. To get a better idea of your individual chances for success based on your age and the number of mature eggs you can expect to retrieve, you can visit our Egg Calculator.

alertarrow_downarrow_left_largearrow_left_largePage 1checkboxemail_s1D9FFAA3-EA4C-4372-92E5-C3D5456F45D4footer_icon_fbfooter_icon_fbfooter_icon_instafooter_icon_twfooter_icon_twfooter_icon_yelpIcon/hero-arrowIcon/hero-arrowMenu Iconicon_bookicon_closeicon_loginicon_quote_1icon_quote_2icon_teamC5A1F0E9-A82D-464C-90CB-83D5F18FB165ArrowArrow16FD96C6-4422-43F6-ACA8-6CF60F2AD146