In vitro fertilization, known as IVF, is a medical procedure in which a woman has an already fertilized egg inserted into her womb to become pregnant.
It is used when couples are unable to conceive naturally, and a sperm and egg are removed from their bodies and combined in a laboratory before the embryo is inserted into the woman.
Once the embryo is in the uterus, the pregnancy should continue as normal.
The intervention can be done using eggs and sperm from a couple or from donors.
National Institute for Health and Care Excellence (NICE) guidelines recommend that IVF should be offered on the NHS to women under 43 who have been trying to conceive through regular unprotected sex for two years.
People can also pay for IVF privately, which costs an average of £3,348 for a single cycle, according to figures released in January 2018, and there are no guarantees of success.
The NHS says success rates for women under 35 are around 29%, with the chances of a successful cycle decreasing as they get older.
Around eight million babies are thought to have been born through IVF since the very first case, Britain’s Louise Brown, was born in 1978.
Chances of success
The success rate of IVF depends on the age of the woman undergoing treatment, as well as the cause of infertility (if known).
Young women are more likely to have a successful pregnancy.
IVF is generally not recommended for women over 42, as the chances of a successful pregnancy are considered too low.
Between 2014 and 2016, the percentage of IVF treatments resulting in a live birth was:
29% for women under 35
23% for women aged 35 to 37
15% for women aged 38 to 39
9% for women aged 40 to 42
3% for women aged 43 to 44
2% for women over 44
