Women who have multiple births as a result of in vitro fertilisation (IVF) are more likely to be depressed and unhappy with the results than single-birth mothers, research has found.

Experts said multiple births were linked to "significant social risks", even among couples wealthy enough to cope with the cost of having several children at the same time.

The study raises questions about the large number of twins and triplets born as a result of fertility treatment and about the number of embryos which should be transferred into a woman in each IVF attempt. The Human Fertilisation and Embryology Authority (HFEA), which regulates fertility treatment in Britain, stipulates that no more than two embryos should be implanted, although in exceptional circumstances doctors can transfer three. The HFEA is now considering whether to amend the rule and limit it to a single embryo, with two allowed only in exceptional circumstances.

Increasing use of fertility treatment has led to a doubling of the number of multiple births during the past decade.

Researchers from Harvard Medical School in Boston interviewed 300 mothers who had a multiple birth and compared them with 128 mothers who had a single birth.

All the women had undergone fertility treatment, and were wealthy and educated to degree level, with a high socio-economic status.

Their results, presented at the American Society of Reproductive Medicine confer- ence in Texas yesterday, revealed that multiple-birth mothers were significantly more likely to be depressed and less satisfied with their partners and home life. Their quality of life was much lower and they felt less secure about their abilities as a mother.

While these problems were obviously related to the stresses of bringing up two or more children of the same age, the researchers also found that multiple births left many women questioning whether they should have undergone fertility treatment.

Marcia Ellison, the lead researcher, concluded: "Multiple births resulted in more negative appraisals of their decision to seek treatment and of reproductive science. Multiple births resulted in a trend towards significantly more negative evaluations of their treatment outcome.

"The results indicate that multiple births result in significant social risks which compounds previously recognised medical risks.''

Alison Cook, a spokeswoman for the HFEA, said: "These results show that multiple births are not good for the mother or the children and any way that we can reduce them without disadvantaging a woman's chances of getting pregnant should be considered.

"Multiple births are linked to higher risks for mothers and children, and it is something that does concern the HFEA.

"Women are designed to carry one child; not twins or triplets or quadruplets. Any way we can get fertility treatment births closer to the norm should be considered.''

The HFEA will publish its proposals for a revised code of practice on the number of transferred embryos in December. For some older women, Ms Cook said, transferring more than two embryos offered a greater chance of getting pregnant, and guidance would take into account their chances of conceiving with a single embryo transfer.

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