IVF is one of the most effective infertility treatments; it has resulted in over 190,000 live births since Louise Brown, the first baby to be born as a result of IVF, arrived in 1978. However, there is no guarantee that every cycle of in vitro fertilisation will result in a live birth, even if the healthiest and most promising-looking embryos are transferred to a healthy uterus.
On average, IVF has a success rate of around 33 % per embryo transferred for women under 35 years old. Success rates per cycle are slightly higher as more than one embryo is usually transferred. With a series of cycles, especially those including embryos frozen from the first cycle, more than 90 % of healthy women will eventually conceive using IVF, as long as there are no other gynaecological factors preventing them from doing so.
A US study has shown that the success rate of IVF does drop away sharply, however, from around 40 % per cycle for women under 35, to just 22 % for those between 38 and 40, and only 12 % for women between 41 and 42. Sadly, these figures represent live births, with actual conception rates at 30 % for the 38–40 group and 20 % for 41–42. So the older you are, the higher the risk of a miscarriage, even if you do manage to conceive with IVF.
If you are using eggs from a donor, then the success rate of the IVF treatment is influenced by the age of the donor, rather than your own age.
Other factors that will reduce the effectiveness of IVF include stress, weight, smoking and alcohol intake. A body mass index in the high twenties or above will reduce your chances of conceiving by around a third, and regular smoking will have a similar effect.
The skills of the clinic will also have an influence on how effective IVF treatment is, and most clinics will publish their success rates for different forms of treatments and different age groups.
At the end of the day, however, there are no guarantees. Just like natural conception, fertility treatment using IVF still remains in the hands of nature in the end, and your conception will always be partly down to chance.