Twin births DOUBLE in 40 years in Developed Countries
Twin births have almost doubled in developed countries within just four decades, a new study has revealed. The increase has been described as "an important public health issue" for babies and their parents.
In England and Wales, the rate increased from 9.9 twins per 1,000 deliveries in 1975 to 16.1 in 2011, the researchers found.
The figures were similar in the U.S. - from 9.5 twins to 16.9, Germany - 9.2 to 17.2, France - 9.3 to 17.4 and Denmark - 9.6 to 21.2. South Korea also saw a jump from 5 to 14.6.
Describing the increase as an "important public health issue" for babies and their parents - with medical problems and even the risk of divorce increasing with multiple births - the researchers attributed the surge to a "sharp rise" in the use of fertility treatments, and older mothers.
A spokesman from the research team from France's Ined demographic research institute said: "Techniques like ovarian stimulation and in vitro fertilization (IVF) are associated with a greatly increased risk of multiple births.
"However, in the same period, the mean age at childbearing has also increased considerably, and the incidence of multiple pregnancies is known to increase with the mother's age."
The increase in twin births is an "important public health issue, because twin babies are more fragile than singleton ones", the researchers wrote in the journal Population and Development Review.
The report said: "They have lower birth weight, more complications at birth, and are more often born premature-all of which are associated with many long-term health problems.
"Stillbirth and infant mortality rates are also much higher among twins than among singletons.
"Having twins can also have negative effects on parents. Twin pregnancies are associated with higher risk of gestational diabetes, pre-eclampsia, postpartum depression, and increased divorce risk."
The researchers said that in the last 15 years, the rising concerns about the high number of multiple births, and their associated health risks have led to changes in fertility treatment practices in some countries, including a reduction in the number of embryos transferred to the mother's womb.
The report added: "At the same time, however, the number of treatments continues to increase, and the average age of women undergoing these treatments is rising.
The researchers found that, for England and Wales, women aged 35-39 were the most likely to give birth to twins, with 16.4 twins per 1,000 deliveries in this age group.