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What Are the Risks of Egg Freezing?

Updated: Oct 13, 2022

Despite the huge uptake in elective egg freezing, it’s a relatively new procedure, so doctors and scientists are still building up the empirical data to understand the full risk profile.

While taking medication and during the retrieval procedure itself, you'll be under the care of trained fertility specialist doctors and nurses whose number one job it is to keep you safe. But, as with any medical procedure, there are some potential long and short-term health risks - some to your physical health and some to your emotional wellbeing (think: how will you feel if it doesn't work?)

The data that does exist for egg freezing cycles tends to focus on non-healthy women, given the fact egg freezing only used to be done for medical reasons. This dataset is small - some figures suggest that only seven percent of women have so far “gone back” to use their eggs161 - and, though it is informative, the data is not necessarily representative of healthy women undertaking egg freezing. As more and more healthy women go back to use their eggs that were frozen for age-related reasons, a more specific dataset will evolve. In the meantime, much of what is understood about the risks and safety of egg freezing is derived from studies that looked at IVF cycles.

So while over 2.4 million cycles of ovarian stimulation take place each year around the globe,162 the ASRM cautions that there is not enough data now to know all the possible risks. The organization’s guidelines state, “while short-term data appear reassuring, long-term data on developmental outcomes and safety data in diverse (older) populations are lacking.”163

Before we get into more specific risks and side effects, let’s cover some common, broader

findings that address concerns you might have:

Egg freezing is regarded as safe

Despite their caveat about the size of the dataset, the American Society for Reproductive Medicine (ASRM) says that:

“Most of the medical procedures involved in planned egg freezing are well established; ovarian stimulation, oocyte [egg] retrieval, embryo culture, and embryo transfer are all regular components of IVF that are well tested, used worldwide, and regarded as safe.”164

The risks of egg freezing are similar to those associated with ovarian stimulation before IVF. If you have concerns, raise them with your doctor.

No causal link with cancer has been identified

This is a common fear based on reports that women receiving fertility treatment have higher

rates of cancer (e.g. breast, endometrial, and ovarian), but in studies, no causal link has been

identified. While some studies suggest an increased risk of cancer, most do not.165 166 167 168 169 170 171

Researchers believe the correlation might be explained by surveillance bias172 (women undergoing ART treatment undergo scans and ultrasounds which increases the chances that

cancer will be found) or patient profiles (women who need fertility treatment are already more

at-risk as a group).173 174 175 Studies have shown that even women with breast cancer are not

more likely to have a recurrence if they undergo ovarian stimulation.176

DOCTOR INSIGHT: “In general, older studies linking increased cancer risk to fertility

treatment suffered from methodological limitations – mainly failing to find an appropriate

control, or control for confounders like infertility itself, which is linked with increased risk of

cancer. The increased cancer risks noted were deemed due to differences in underlying risk

factors in infertile patients compared to fertile patients, rather than the treatments. It is generally

well accepted that there is not an increased risk of invasive breast, ovary or thyroid cancer

related to fertility treatments. Long-term studies are ongoing.” - Dr. Eleni Greenwood Jaswa, University of California, San Francisco

DOCTOR INSIGHT: “Hormonal therapy itself does not cause cancer. It can, however,

stimulate the growth of cancerous cells. Therefore, if a person currently has cancer, or has a

higher risk of developing cancer due to their unique genetic composition, hormonal therapy

would be contraindicated. Before administering any hormonal therapy (for infertility or

otherwise), doctors should screen their patients for any genetic abnormalities that may

predispose the patient to cancer.” - Dr. Aimee Eyvazzadeh, Private Practice Physician, San Ramon

DOCTOR INSIGHT: “If a woman is in any way concerned because of age or family history

I suggest a baseline mammogram before starting stimulation.” - Dr. Diana Chavkin, HRC Fertility, Los Angeles

DOCTOR INSIGHT: "Infertility is an independent risk factor for breast/uterine/ovarian

cancer, however the treatments used [ovarian stimulation etc.] do not pose additional risk." - Dr. Meera Shah, Nova IVF, Mountain View

In essence, women who experience infertility are known to have higher rates of female

cancers (which accounts for some of the scare stories), but these cancers are not caused by the

fertility treatments. Research is still ongoing into the reasons for the link. Every one of the

fertility doctors on our expert panel say there is no robust evidence that egg freezing will

increase your risk of cancer, nor is there clear biological plausibility.

The only risk may

potentially be in women who already have breast cancer, because the hormones in an egg

freezing cycle may stimulate it in a minor way, but this is still considered "irrelevant." Despite

these reassurances, if you have concerns, especially if you have a family history of cancer, make

sure to raise them with your own doctor.

Egg freezing does not reduce your risk of having a natural birth in the future

A common misconception is that by stimulating and freezing multiple eggs, you are “using

up” eggs from your ovaries that could be used for a natural birth in the future. Don’t worry,

that’s not the case. You would have lost those follicles and eggs regardless. In a normal month,

your body loses around 1,000 follicles, of which only a single one usually matures to the point of

ovulation.177 You would also lose these eggs if you were taking birth control pills or during

pregnancy. If it was actually the case that you have a certain number of eggs and you ovulate

until they run out, stopping ovulation by taking birth control pills would then surely delay menopause! (Unfortunately that’s not the case.)

In an ovarian stimulation cycle for egg freezing, what happens is that a few of those other spare 999 follicles, which would normally be reabsorbed into the ovary (or “lost”) that month, are stimulated into the next stage of maturation and retrieved by your doctor. You’re effectively making use of some of the spare capacity.

The fact of the matter is, you will only ovulate around 500 times in your lifetime out of all the

millions of eggs you started with: 99% of the follicles are wasted.178 There are plenty to spare for

multiple cycles of egg freezing. In short, doing IVF or an egg freezing cycle does not lower your

chances of fertility in the future, nor does it cause you to have menopause at an earlier age. This

is because the eggs that are retrieved are eggs that would have been lost regardless.

Babies from frozen eggs are not more likely to have birth defects

About one in every 33 babies is born with a birth defect, also called congenital disorders.

Not all birth defects can be prevented, though age is a big risk factor. Babies born via ART with

frozen eggs show no more likelihood of having congenital anomalies than those born via ART

treatments using fresh eggs.179 180 As such, there’s not thought to be any difference in risk using

fresh or frozen eggs. Even before the new, improved freezing technology came along, by 2009

more than 900 babies were born from frozen eggs and according to a committee from the

ASRM, there was no apparent increase in congenital anomalies among these babies.181 182

However, babies born via ART are seen to have more congenital anomalies when compared

to naturally conceived children.183 184 185 186 187 188 Studies vary, but it’s suggested that this amounts to slightly increased risk.189 The thing is, this may be a case of correlation, not

causation. Babies born to infertile couples also have higher rates of congenital anomalies

whether they were conceived naturally or via ART, which is why some researchers say this

indicates the treatment itself might not be the cause.190

So, if there’s not necessarily a risk because of the actual technological process, why the

slightly increased percentage of ART babies born with birth defects? Researchers make the point

that women undergoing ART are already at higher risk of having babies with birth defects

because of their riskier profiles: infertile women are more likely to be older, obese and to have

chronic health conditions (like diabetes, high blood pressure, and epilepsy), all of which are

independent risk factors for congenital anomalies in the first place.191 192 193 194 Women who have experienced a hard time getting pregnant or staying pregnant and who have turned to ART to help them have a baby may also have a higher threshold for abortion, given the challenges they have faced, possibly leading to more babies born with birth defects. ART pregnancies are also more closely monitored than general pregnancies, so more congenital anomalies may be

identified simply because more are diagnosed and recorded. There are plenty of plausible

explanations for the slightly increased risk that mean it’s not actually to do with the process


It’s now generally agreed that there is no difference in likelihood of having a healthy baby

whether a fresh egg or a frozen egg is used. However, we should point out that the fresh v. frozen

studies done were primarily on women under the age of 35 years old - there haven’t been similar

ones on women older than that, so nobody can say for sure if there might be a difference after

that age. With that said, studies are still ongoing into the link between ART and birth defects and

more research is needed before the picture is crystal clear.195

Other pregnancy risks are probably not to do with the process itself

What is clear from the data is that women who undergo IVF are more likely to have twins,

triplets and other riskier multiple pregnancies. However, that is usually as a result of doctors

transferring more than one embryo into the womb, rather than because of the fertility treatment.

It is generally considered now that single embryo transfer is best for the health of mother and

baby. Ectopic pregnancy (when a fertilized egg doesn’t properly attach to the womb) and the

pregnancy complication preeclampsia (with symptoms including high blood pressure) appear to

be more common in assisted conception than in natural conception. However, researchers think

that the increased risk of these conditions is most likely related to a woman’s fertility problems

and the fact she’s more likely to be carrying more than one baby at a time.”196 As a result, it’s

not thought to be the actual processes of assisted conception increases these risks.


The Side Effects

You can expect some short term side effects

The short-term side effects of the procedure are clear and are generally minor. (Long term

side effects are considered safe, but, as with all things in egg freezing, are still being studied.)

While there are usually no dramatic or serious side effects, the main thing you should expect

is that during and immediately after ovulation stimulation and egg retrieval, your ovaries will be

enlarged due to the stimulation hormones, which can feel really uncomfortable. For most

women, this temporary bloating and some PMS-like symptoms are the extent of the egg freezing

side effects. These side effects should only last for the days the medication is taken and subside a

few days after the procedure. There are some other things to watch out for though:


● Bloating - During stimulation and for several days after retrieval, a degree of abdominal

bloating is common and expected.

● PMS-like symptoms - This might include headaches, mood swings, insomnia, hot or

cold flashes, breast tenderness, mild fluid retention.

● Fatigue - This isn’t just when recovering from the sedative after retrieval, but can

manifest during the hormone injection period, too. Think of it a bit like how your energy

levels can fluctuate during your menstrual cycle along with hormones.

● Bruising - The hormone injection site on your abdomen could become sore, red, or

slightly bruised. Switching up the injection site throughout the process can help with


● Grogginess after retrieval The sedative used for the retrieval procedure is similar to

that used by dentists for wisdom tooth extractions. It’s commonly a propofol-based

sedation medication sometimes called “twilight” anesthesia or a “deep sleep” and is

monitored anesthesia care. It carries an extremely low risk of complications and doesn’t

require a breathing tube. Still, you’ll probably feel groggy afterward as it wears off (like

a sleeping pill), which is why you won’t be able to drive home.

Somewhat likely:

● Cramping - After the retrieval procedure, some women report feeling discomfort

around the ovaries and lower abdomen due to puncture sites on the ovary and the vagina.


● Menstrual cycle problems - rare - Your menstrual cycle should return to normal with a

period one to two weeks following the procedure, though some women do experience

spotting. Speak to your doctor if you do not get a period within two weeks of the

procedure. The next period is sometimes delayed as the body “resets.”

Very rare:

● Bleeding or infection - Bleeding as a result of the procedure can happen, but this is

extremely rare. If you experience symptoms like the ones below call your clinic.

According to Dr. Eleni Greenwood Jaswa, “Bleeding after a procedure may accumulate

in the belly and cause abdominal/pelvic pain, shoulder pain (the nerves irritated by blood

in the abdomen are sensed in the shoulder), dizziness, lightheadedness, feeling faint or

weak. Often, women who have procedural bleeding into their belly will not seeing

vaginal bleeding.”

● Infection - Infection as a result of the procedure can also happen, but this is also

extremely rare. Some clinics may give antibiotics to prevent infections.

● Moderate Ovarian Hyperstimulation Syndrome (OHSS) - Affects less than 5% of

women - Mild-to-moderate ovarian hyperstimulation syndrome involves fatigue, nausea,

headaches, abdominal pain, breast tenderness, and irritability, but these adverse effects

can usually be well-controlled.197

● Severe Ovarian Hyperstimulation Syndrome (OHSS) - Affects less than 1%. (Many

clinics have been replacing the use of hCg as the trigger shot with GnRHa instead,

which advocates of that treatment protocol say has greatly decreased OHSS, in the last 5

years, especially in at-risk women.) 198 - Symptoms of moderate OHSS include extreme

bloating, thirst and dehydration. You may only pass small amounts of urine, which are

dark in color, and/or you may experience difficulty breathing, abdominal pain,

dehydration, and vomiting. A serious, but rare, complication is the formation of a blood

clot (thrombosis) in the legs or lungs. The symptoms of this are a swollen, tender leg or

pain in your chest and breathlessness.199A very small number of deaths due to OHSS

have been reported. Although there is no treatment that can reverse OHSS, it will usually

get better with time.200 Severe OHSS can be thought of as the loss of control over

stimulation of the ovaries.201 With careful dosing and monitoring, most cases can be

avoided. If you have concerns about OHSS, raise these with your doctor. Note that the

risk is higher if you are under 30 years old (as you are more likely to have a higher

number of eggs),202 if you’ve had OHSS before, if you have PCOS, 203 204 or if you have

other medical problems like hypertension, diabetes, obesity, hypothyroidism or anemia.


● Anesthesia risk - Less than 1% risk of difficulty breathing and low blood oxygen for

women of normal weight, but of more concern for obese women.206 Where general

anesthesia is used, it comes with its own set of risks, which is proportionately higher for

women that are obese. This is why many clinics have upper limits for BMI for the

patients they will treat. Make sure to let your doctor or nurse know if you have ever had a

reaction to an anesthetic or sedative, or if you are allergic to any medications.

● Damage to nearby organs like bowel/bladder/blood vessels - Less than 1% risk. The

procedure is performed under transvaginal ultrasound guidance to avoid this

complication. 207

● Ovarian torsion - Though very rare, an ovary may twist around the ligaments that hold it

in place, potentially cutting off blood flow to the ovary and fallopian tube.208 The chance

is slightly increased due to their enlargement. To avoid ovarian torsion, many clinics

recommend avoiding vigorous exercise during and after the treatment cycle until the

ovaries have returned to their normal size. 209

● Pregnancy - Although rare, this can happen. A lot of clinics recommend not having sex

during an egg freezing cycle.

Your own medical history and individual health may mean an increased risk of one or more

of these side effects, so always discuss these with your doctor at length.

“I felt fine most of the time. I just felt a bit tired.” - Shannon, 36

“I found the bloating really, really uncomfortable. I couldn’t sit still and things didn’t

properly go back to normal until about a week after my procedure.” - Hannah, 33

DOCTOR INSIGHT: “Feeling fatigued is probably the most common complaint/feedback I

get during stimulation and is not necessarily due to OHSS. I tell my patients, when counseling

them on how they may feel, is that in almost 30 years of doing this, I cannot remember a single

patient who stopped her medications prior to egg retrieval due to side effects.” - Dr. Diana Chavkin, HRC Fertility, Los Angeles


Other things to bear in mind


Though egg freezing has only become way more popular in recent years, it's not a new procedure by any measure - in fact, the first baby born from a frozen egg is now over 30 years old.

Since then, treatment protocols, equipment and attitudes have all evolved, so some of the stories and stats you hear from years ago don't accurately reflect outcomes now - just keep an awareness of this whilst doing your research. (And if you're unsure of anything - ask your doctor directly.)


Understanding the statistical outcomes as they are likely to pertain to you individually is a CRUCIAL part of your preparation. There may be egg freezing considerations or risks specific to you and your health. When you go into a fertility clinic, your doctor will take your full medical history. Along with preliminary tests, this will determine whether you are what they might call a good "candidate' for the procedure.

They should also let you know about any egg freezing side effects or procedure-related risks as they pertain to you individually based on your general health.


"How many did you get?!"

Get ready, that's the first question you'll hear from anyone you tell you froze your eggs. You may have found that there are a variety of perspectives on exactly how many eggs you want to have retrieved in order to secure a live pregnancy in the future. The more eggs you have frozen, the more chance of them making a baby in the future.

BUT what also really matters is how many of those are of a quality worth keeping - the elites. These are the eggs most likely to be abnormality-free, freeze well and make an embryo.

Quality is key because 95% of embryo health comes from the egg so, in theory, high quality eggs produce high quality embryos. Embryos must be strong enough to survive the early stages of development in order to have a successful pregnancy in the future. Poor quality eggs can can mean the difference between carrying your baby to term, or losing it in the first few weeks if it doesn’t implant properly.

Whilst freezing enough eggs to increase the overall chances of a successful birth in the future, studies show that more hormones might equate to more eggs, but those eggs start competing with each other and thus the quality is sacrificed. As such, the current thinking is that freezing more than 20 eggs in one "cycle" could potentially impact quality, though more research is needed in this area.


Egg freezing is a wonderful way to improve your odds of being able to future-proof your fertility, but - as every healthcare provider should be upfront in telling you - there are no guarantees.

The pre-screening tests are there to give you the best idea on how many eggs you might produce and how many end up being frozen but this is an indication using all the inferences available, rather than an absolute.

Also, whilst egg freezing and fertility technology is advancing at an incredible rate, there are situations down the line that can also affect the usability of your eggs, which you should be aware of:

  • Storage facility failure - this is very rare but has happened.

  • While studies indicate that there is no "expiration date" for your eggs, some countries like the UK have laws that prevent you from storing them for more than 10 years. This is an important consideration when choosing a country to store them. South Africa and the US have no limit.

  • The reality of needing multiple cycles. Depending on your age and the number/quality of eggs retrieved, there's a chance that you'll need to undergo multiple cycles in order to further futureproof your fertility. In almost all circumstances, your doctor will have a good indication of whether or not this is the case and will discuss your options accordingly. Just think, more chances to come on a fabulous retreat!

  • Of the eggs that are retrieved, some may not be suitable for freezing, some may not survive the freezing and thawing processes and some may not fertilize or develop into normal embryos. Of the embryos that are transferred, only some will result in a pregnancy, and some pregnancies miscarry. Freezing your eggs is no guarantee of a baby, it's a way of storing your own young eggs so that you have the potential to use them in IVF treatment (rather than, let's say, using donor eggs) if you ever need it. As such, IVF success rates are a good guideline.


We've gone through the exact same process you are going through right now. It's totally normal if you're feeling overwhelmed, like you're coming across a whole lot of sometimes conflicting data and opinions that are holding you back from actually making a decision on this. Particularly the scaremongering stories that don't seem to be based in any actual facts.

But know that reading things like this, considering your options and educating yourself about your fertility health and your options is only a good thing. We don't have full control over a lot of things in life - fertility included. But once you balance all the inputs you are better able to know whether taking the step to freeze your eggs is going to feel to you like it does offer you that bit more security.

We're on a continual mission to streamline all the information and make sure that you are able to formulate your own opinions/decisions so please let us know if you want to ask a question or flag up something we should cover


Still deciding if egg freezing could be right for you?

Take our 1 hour digital interactive decision-tool video workshop:


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