You may have heard of, or know personally, mothers who have successfully carried and given birth to twins or more babies. Newspapers and magazines often carry articles on such families, and the story is usually one of joy, rather than heartache.
Unfortunately, this rosy picture hides the reality for the women who suffer a miscarriage or life-threatening conditions during pregnancy, or who, in extreme cases, die during pregnancy or labour.
At present, about 1 in 4 in vitro fertilisation (IVF) / intra-cytoplasmic sperm injection (ICSI) pregnancies leads to the birth of twins. This means that after IVF/ICSI, you are around 20 times more likely to have a multiple pregnancy than you would be if you'd conceived naturally.
Other fertility treatments, such as drugs and intrauterine insemination (IUI) can also increase the risk.
Multiple pregnancy and birth carry significant risks to the children and they also carry considerable risks for mothers. See Risks to the child for more information.
"Multiple births increase risks for mothers and babies. They should not be seen as inevitable and acceptable outcomes of assisted reproduction."
Prof Siladitya Bhattacharya, University of Aberdeen
The risks to mothers from multiple pregnancy and birth range from the mild to the potentially life-threatening.
Risks during pregnancy
During pregnancy, mothers of twins are at greater risk of various serious health problems, as well as the risk of losing their babies.
Risks during or after birth
During birth, mothers of twins are more likely to require intervention, more likely to experience serious problems and more likely to die than mothers of singletons.
Even the less serious problems may result in the mother spending longer periods in hospital than would normally be necessary. You may have to spend the last weeks of your pregnancy in hospital, and the birth may have to be induced early.
The HFEA want to hear your views on single embryo transfer.
Your feedback will help them develop their approach to the risk of multiple births from fertility treatment.