A drive to cut twin and triplet births appears to be paying off, with 22% of births in the first six months of 2009 being two or more babies, down from 24% in 2008.
The Human Fertilisation and Embryology Authority (HFEA) launched the initiative in January 2009 with the overall aim of cutting the IVF multiple birth rate to 10% in the coming years. All IVF clinics must now have a strategy for reducing their number of multiple births.
Twins and triplets, whether conceived through IVF or naturally, have a higher risk of health problems than single babies. Half of all twins are born prematurely and have a low birth weight of under 5.5lbs (2.5kg).
Triplets have a 90% chance of being born prematurely and of low birth weight, and the risk of premature babies dying in the first week is around five times higher for twins and nine times higher for triplets than single babies.
Twins are also four times more likely to have cerebral palsy than single babies, while triplets have a risk that is 18 times higher.
Women who are carrying twins or triplets have higher chances of miscarriage, anaemia, haemorrhage, early labour and needing a Caesarean section. And up to a quarter of multiple pregnancies will lead to high blood pressure in pregnancy.
Around 80% of IVF treatment is carried out in the private sector and the HFEA has been urging private clinics to drive down their rates.
Women under 35 have a higher chance of success through IVF and therefore a higher chance of multiple pregnancy if two or more embryos are transferred.
The latest HFEA figures show that among women aged 18 to 34, 31.2% of pregnancies (not births) in 2008 were multiples, but by mid-2010 this had fallen to 23.9%.