International Federation of Gynecology and Obstetrics

The rate of triplet births has increased, even after excluding pregnancies that are a result of assisted reproductive technology, according to new research.

Researchers in Norway analysed over two million pregnancies during a 40-year span from 1967 through to 2006.

They discovered the rate of triplet births is nearly 2.5 times what it was in the 1970s, with 2.7 occurring in every 10,000 pregnancies.

Although the death rate for single, twin and triplet pregnancies have fallen over the past four decades, deaths are still ten times as likely to occur during triplet births than single-child ones.

Doctor Anne Tandberg of the Haukeland University Hospital in Bergen told Reuters: "Advances in obstetric practice and perinatal care have increased the survival of very preterm infants. However... the improvements have not been so favourable for triplets compared to twins and singletons."

Meanwhile, a survey carried out by Britain's Twins and Multiple Births Association has discovered that parents with twins or triplets are more likely to end up divorced or separated.