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IVF: some risks and side effects

IVF treatment is a medical and surgical procedure which carries its share of side effects and risks. Side effects are common events that seldom pose a threat to health or life although they may be unpleasant and painful. Risks are uncommon events that can potentially have serious and permanent consequences.

IVF treatment is a complex medical and scientific procedure so it is not surprising that unexpected things can sometimes happen even with the best knowledge in the world and lots of experience. If things do not go as well as expected, we will always discuss the options with you before any decision is made.

Below are some problems that can arise during an IVF cycle.

  • Slow down regulation: sometimes down regulation takes longer than expected – usually this just means delaying the start of the FSH injections by another 4-7 days. If a cyst develops it can usually be resolved by giving an injection of hCG. An alternative is to stop the cycle and to start again in 1-2 months time.
  • Stopping treatment for under-stimulation: if fewer follicles develop than expected the best option may be to stop treatment and start again using more medications. This happens in about 10% of cycles. If you have a poor response during a publicly-funded cycle, we will make the decision on whether or not to stop and whether you can be offered another publicly-funded cycle.
  • Over-stimulation: having too many follicles increases the risk of Ovarian Hyper-Stimulation Syndrome (OHSS). The solution depends on the degree of risk. It ranges from stopping the cycle, stopping FSH injections for a few days to cause some follicles to stop developing – which is called coasting, or freezing all the embryos to prevent pregnancy, since pregnancy increases the risk of OHSS - see below for more.
  • Ovulation before egg collection: this occurs in about in about 1 in 200 cycles.
  • No or low fertilisation: unexpected low or no fertilisation can arise because of a sperm factor, an egg factor, or can just be unexplained. It seldom recurs and the pregnancy rate in subsequent cycles may be normal.
  • Infection of culture dishes: very occasionally culture media may become contaminated with bacteria from the semen or from the vagina during egg collection which leads to the embryos dying. There are various strategies to minimise the risk in subsequent cycles.
  • Delayed or abnormal embryo development: almost everyone has at least some embryos that stop developing normally by the time of embryo transfer. Occasionally all embryos stop developing before day two or three so that there are no embryos to transfer. When this happens it can be very difficult to advise what to do next – for some people the problem will recur in another cycle, while for others it is a ‘one-off’ phenomenon that probably arose by chance.

Common side effects

  • Mild post-menopausal-like symptoms, such as hot flushes, headaches, sore breasts, tiredness and occasionally nausea. These are caused by the rapid changes in hormone levels from taking the medications to stimulate the ovaries.
  • Mood swings, usually following the start of the FSH injections. Many women report being more tearful than usual. Mood swings are also caused by the rapid changes in hormone levels.
  • A sharp but fleeting pain when the egg collection needle punctures the ovaries at egg collection, and sometimes at other times during egg collection. This pain is due to movement of the ovaries.
  • A small amount of bleeding from the vagina after egg collection where the needle went through the vaginal wall. A small amount of brown blood loss for one or two days is common.
  • Sore ovaries for one or two days after egg collection.
  • Nausea and not remembering the procedure are common side effects of the sedative and narcotic medications used during egg collection.
  • Mild abdominal discomfort or bloating from the medications used to stimulate the ovaries, sometimes before but mainly after egg collection.
  • There is a small chance of bleeding from the cervix after embryo transfer, on the day of transfer or the next day. This is not believed to affect the chance of pregnancy.

Risks for the woman

  • Respiratory depression: the medications used for egg collection can reduce the amount of air you breathe and thus the oxygen in your blood. We monitor your oxygen level during and after egg collection with a pulse oximeter. If your oxygen level falls too low, the doctor will stop collecting eggs and give oxygen. Very rarely you may require emergency drugs. Brain damage and death are theoretically possible, but so rare that no figures are available for IVF.
  • Pelvic infection after egg collection: pelvic infection can occur when the egg collection needle carries bacteria from the vagina or the bowel into the abdomen, or transfers bacteria from a damaged Fallopian tube into the abdomen. Infection occurs in about 1 in 500 cycles. The chance of infection can be reduced by giving antibiotics after egg collection if the needle punctures a damaged Fallopian tube, the bowel or an endometriotic cyst.
  • Vaginal bleeding after egg collection: vaginal bleeding of more than 100 ml (half a cup) occurs in about 1 in 100 egg collections, but usually settles quickly.
  • Internal bleeding after egg collection: puncture of a large blood vessel in the abdomen during egg collection occurs in about 1 in 1000 procedures. This may cause severe pain, and would usually occur before you went home. Another symptom of internal bleeding can be shoulder-tip pain caused by blood irritating the diaphragm.
  • Vaso-vagal reaction: there is a small chance of a vaso-vagal reaction at the time of embryo transfer. This is an involuntary reflex that causes the heart to slow, blood pressure to drop, and fainting. The embryo transfer is usually stopped and done at a later time.
  • Uterine infection after embryo transfer: uterine infection after embryo transfer occurs in about 1 in 300 transfers. The symptoms are feeling sore or unwell, or a fever. Infection usually settles with antibiotics. There have been cases of damage to the uterus or Fallopian tubes, but this is very rare. Infection is likely to reduce the chance of pregnancy.
  • Ectopic pregnancy: when an embryo implants in a Fallopian tube, the cervix or the abdomen, it is called an ectopic pregnancy. Ectopic pregnancies can be dangerous because the placenta can burrow into a blood vessel and cause major internal bleeding. We can usually detect an ectopic pregnancy by the level of hCG in pregnancy tests and an early ultrasound scan, but not always. Symptoms include severe, localised abdominal pain.

More about Ovarian Hyper-stimulation Syndrome (OHSS)

The following are possible symptoms of OHSS – if you have any of the these contact the clinic the same day:

  • weight increase of 2 kg or more may be an early sign of OHSS – contact the clinic the same day;
  • increasing abdominal (tummy) pain;
  • abdominal bloating or swelling;
  • nausea or vomiting;
  • decreased urine output;
  • shortness of breath or difficulty breathing;
  • severe headache.

Because OHSS only occurs with fertility treatment, the symptoms could be misinterpreted as appendicitis if you see a non-fertility doctor. If you see another doctor, please tell him or her that you have just had ovarian stimulation for IVF, and ask the doctor to contact the clinic. You may take paracetamol (Panadol) to relieve the pain.

OHSS is the most serious risk in IVF. A mild form occurs in up to 20% of women undergoing IVF, and the severe form in about 1–2% of women. If it is not treated, severe OHSS can cause blood clots, stroke and even death.

Why it occurs in some people and not in others is unknown, but it only occurs after the ovaries have been stimulated and then exposed to hCG. It is more common in women who produce more follicles after IVF stimulation, and in women who have Polycystic Ovary Syndrome (PCOS). It seldom occurs until four days or more after the hCG trigger injection. It occurs more commonly in women who become pregnant. Physiologically, it occurs when fluid moves from the blood into the abdomen or the lungs.

Mild and moderate cases are usually treated with observation and pain relief, but more severe cases always require admission to hospital. In hospital you may be given intravenous fluids or have fluid drained from the abdomen. If you are a New Zealand resident any hospitalisation as a consequence of IVF treatment is free, but if you are not a resident you will be personally responsible for costs of being admitted to hospital.

We take several active steps to reduce the chance of OHSS. We also help you detect the beginning of OHSS by measuring your weight at embryo transfer and then asking you to measure it every two days.


Ovarian torsion

In about 1 in 500 cycles an ovary becomes twisted around its blood supply which can cause severe and sudden pain and sometimes the loss of the ovary. It is more common in women who respond well to the IVF medications and who become pregnant. It is usually resolved by surgery to untwist the ovary.

For more information on the following please see our IVF Basics in the Pathways Magazine.

  • Side effects and risks for men having Surgical Sperm Retrieval (SSR)
  • Longer term risk of IVF
  • Pregnancy and childbirth
  • Multiple pregnancy
  • Sperm and embryo storage
  • Wellbeing of IVF children.

Good to know: about pain

Pain is your body’s way of saying that something may be wrong. We need to know about any symptoms that might be concerning you.

Immediately contact your clinic, your doctor or GP if you experience any of these symptoms:

  • more than a small amount of vaginal bleeding.
  • pain after egg collection or shoulder-tip pain the day of egg collection.
  • if you feel sore, feverish or unwell anytime after embryo transfer, phone the clinic immediately.
  • localised abdominal pain when you are pregnant.

If you experience these symptoms contact your clinic, your doctor or GP on the same day:

  • Fever and abdominal pain - these are the symptoms of infection.

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The Biological Clock

This tool indicates:

  • Natural conception per month if you have no fertility issues
  • IVF success rate at the same age
  • When to seek help after months of unsuccessful attempts

If you are concerned at any stage – we recommend booking a doctor appointment or a free nurse consultation. The sooner you make a plan the better your chances in the long term.

When to seek advice early

  • If you have polycystic ovaries, endometriosis, or have been through a cancer diagnosis; we recommend you get in touch quickly so we can talk you through all your options and give you the greatest possible chance of success.
  • If you’re a single woman considering motherhood in the future; it’s best to approach us early and consider egg freezing as this can be an option for you while you have a higher ovarian reserve and healthier eggs.
Set your age and the months you’ve been trying to conceive
Your chance of having a baby per month for fertile couples
Your chance of having a baby per IVF cycle (if experiencing infertility)

Body Mass Index calculator

Being overweight or underweight can reduce fertility, so it is important to keep your body weight within the normal healthy range.

Body Mass Index (BMI) is an indication of your body weight and can be calculated by dividing weight by height. You should aim for a BMI of between 20 and 25, as this will optimise your chances of conception.

Woman’s BMI below 19

Even in these modern times, nature knows best. If a woman's BMI falls below 19, the body senses famine and ovulation is switched off to prevent the risk of having a baby with malnutrition. Excessive exercise can reduce body fat and increase muscle mass to a point where periods cease for the same reason. Risk of miscarriage is also increased in women with a low BMI.

Being underweight

If a woman's BMI falls below 19, the body senses famine and ovulation is switched off to prevent the risk of having a baby with malnutrition. Excessive exercise can reduce body fat and increase muscle mass to a point where periods cease for the same reason. Risk of miscarriage is also increased in women with a low BMI.

BMI’s greater than 30

This can reduce fertility by 50%. Pregnancy for women with a 30+ BMI is often associated with problems such as maternal diabetes, high blood pressure, big babies and increased risk of caesarean section.

Add your height and weight to calculate your BMI