Each month in a natural menstrual cycle, your body withdraws one gumball (egg) from the machine (your ovaries). That egg is either healthy or unhealthy. As you age, you have fewer gumballs in the machine, and a higher percentage of the gumballs are unhealthy, lowering the chances that the one you get in a given month will be able to result in a healthy baby. That’s why it can take much longer—many more menstrual cycles—for older women to get pregnant.
Even when fertility medicine comes into play, the relationship between age, fertility, and egg quality affect chances of success. Fertility treatments like in vitro fertilization use hormone medications to prompt the ovaries to produce multiple eggs in one cycle, but some of those eggs will still be abnormal (how many are abnormal will depend on your age). So while IVF can help increase the chances of finding some healthy eggs, it can’t make more of your eggs healthy. If a woman in her 40s retrieves 10 eggs in an IVF cycle, it’s likely that only 10–20% of those eggs will be normal. If she retrieves 20 eggs in two IVF cycles, still only 10–20% of those eggs will be normal—but she’ll have more to work with because she retrieved more.
That’s why we see declining success rates as women age, even when using advanced reproductive technology like IVF. If there are very few healthy eggs to work with, the chance of success is low.
IVF involves 6 main stages:
Once the embryo(s) has been transferred into your womb, you’ll need to wait 2 weeks before taking a pregnancy test to see if the treatment has worked.
Read more about what happens during IVF.
The success rate of IVF depends on the age of the woman undergoing treatment, as well as the cause of infertility (if it’s known).
Younger women are more likely to have a successful pregnancy. IVF isn’t usually recommended for women over the age of 42 because the chances of a successful pregnancy are thought to be too low.
Between 2014 and 2016 the percentage of IVF treatments that resulted in a live birth was:
These figures are for women using their own eggs and their partner’s sperm, using the per embryo transferred measure.
The Human Fertilisation and Embryo Authority (HFEA) has more information on in vitro fertilization (IVF), including the latest success rates.
Maintaining a healthy weight and avoiding alcohol, smoking and caffeine during treatment may improve your chances of having a baby with IVF.
IVF doesn’t always result in pregnancy, and it can be both physically and emotionally demanding. You should be offered counselling to help you through the process.
There are also a number of health risks involved, including: