Twin births double in 25 years

2 August 2004

AMSTERDAM — The number of twins born in the Netherlands has doubled in the past 25 years, due primarily to in vitro fertilisation (IVF) treatments, the Central Bureau of Statistics (CBS) said on Monday.

In 1976, there were 1,800 twins born, representing one out of every 103 births. That figure had increased to 3,600 last year, or one out of every 55 births.

The CBS attributed the rise to the increase use of modern medical techniques, such as IVF for people with fertility problems, Dutch public news service NOS reported.

There are especially a higher number of fraternal twins, the product of two fertilized egg cells. But the number of identical twins — born after one egg cell splits into two — has remained almost the same: six out of every 1,000 births.

The ratio between male twins, female twins, or girl and boy twin has also remained about the same, the CBS said.

The number of triplets, quadruplets and quintuplets remains very small. In the 1950s, 60s and 70s, about 25 such births each year involved more than two babies. This represented 1 percent of the total number of multiple births.

But this increased to about 4 percent in 1991, due also to the applied use of IVF treatments. In this period, four to five fertilised egg cells were being placed in a woman’s uterus.

But at the start of the 1990s, the number of fertilised eggs placed in a woman’s uterus during IVF treatment was reduced to two or three, leading to a decline in the number of triplets, quadruplets and quintuplets.

About 120 triplet, quadruplet or quintuplet births were recorded in 1991. At present, a maximum of two eggs are used in IVF treatments and this has led to a decline in births of more than two children to about 70 last year.

Subject: Dutch news