Infant mortality has risen in the US for the first time in 45 years, new US government figures have revealed. The worrying rise is being blamed partly on the increasing use of assisted reproductive therapies such as IVF by couples with fertility problems.
Between 2001 and 2002, the number of US infants dying within their first year for every 1000 live births climbed from 6.8 to 7.0, says the report from the Centers of Disease Control and Prevention (CDC). That is equivalent to nearly 500 additional infant deaths.
Until now, infant mortality in the US has declined every year since 1958. Most of the increase is due to a higher proportion of babies aged less than 28 days old dying.
“We were surprised,” said Joyce Martin, lead statistician for CDC. “You’re always concerned when an important indicator in public health increases,” she told Associated Press. The CDC’s National Center for Health Statistics in Maryland released the new report on Wednesday
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Twins and triplets
Three causes accounted for most of the increase in infant deaths, says the report; birth defects, disorders related to low birth weight and prematurity, and maternal complications of pregnancy.
The rise in multiple births in the US – 42 per cent between 1990 and 2002 – can help explain the increase in premature and low weight babies, write Martin and CDC statistician Kenneth Kochanek. Half of all twins, triplets and other multiple siblings experience these problems.
“The increased use of assisted reproductive therapies (ART) such as in-vitro fertilisation has been strongly associated with the growth in multiple gestation pregnancies and may also be associated with an increased risk of low birth weight among singletons,” they write. One per cent of all births in the US in 2001 were a result of ART.
Delayed motherhood
Andrew Lyon, a consultant neonatologist at the Royal Infirmary, Edinburgh, UK, says the new rise is significant and agrees that it could be explained by more multiple births.
“Twins and triplets tend to be born prematurely,” he told New Scientist. “That certainly would contribute to an increase in deaths early on.”
Lyon says that so far infant mortality in the UK has steadily declined, although multiple births have increased over the last decade as more people seek help for infertility. Also, more women are delaying motherhood to later in life, which may increase mortality.
The UK, like the rest of Western Europe and Canada, currently has an infant mortality rate of about five per 1000 live births, according to UN figures.
But Lyons adds a note of caution about the US rise: “It could be just a blip. It will be interesting to see if it persists.”
