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. It also hides the increased risk of mortality and disability for the babies.
At present, about one in six in vitro fertilisation (IVF) pregnancies leads to the birth of twins. This means that after IVF/ICSI, you are around 11 times more likely to have a multiple pregnancy than you would be if you'd conceived naturally.
Other fertility treatments, such as Clomiphene citrate (tablets used to induce ovulation) and intrauterine insemination (IUI) can also increase the risk.
Multiple pregnancy and birth carry significant risks to the children. Find out more about the risks to the child.
"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.
Even the less serious problems may result in the mother spending longer periods in hospital than would normally be necessary. Women expecting twins may have to spend the last weeks of their pregnancy in hospital, and a high proportion 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.