The number of birth defects among twins and triplets increased nearly two-fold in 14 European countries between 1984 and 2007, according to a new study.
Researchers who had information on more than 5.4 million births occurring over the 24-year period found that congenital defects rose from about 6 in every 10,000 multiples to about 11 in every 10,000 multiples.
"The importance of knowing this is twofold. First, to make sure we have appropriate services available for mothers and babies. The second is to understand the relationship," said Dr. Helen Dolk, the study's senior author.
Dr. Dolk, from the Centre for Maternal Foetal and Infant Research at the University of Ulster in Northern Ireland, said she and her fellow researchers knew multiple births were on the rise and that those babies were at an increased risk for birth defects.
How the study was done
The researchers, who published their findings in BJOG, looked at 5.4 million births in 14 European countries between 1984 and 2007.
The number of multiple births increased by about 50% over that time, the researchers found. Ultimately, 3% of the births were multiple births.
Of the 148,359 major birth defects within those births, about 4% occurred in babies who were multiples.
Over the 24-year period, though, the number of birth defects among multiples about doubled, with a peak between the years 2000 and 2003 of some 12 birth defects per 10,000 multiple births.
The largest increase was in birth defects not caused by chromosomal abnormalities, such as physical deformations - which increased from about 6 per 10,000 multiple births between 1984 and 1987 to about 11 per 10,000 births at the end of the study.
IVF a risk factor
Compared to singleton births, the researchers found the risk of birth defects was about 27% higher for multiples.
According to the researchers, some of the rise in birth defects may be attributed to the increased use of in vitro fertilisation (IVF), which is known to come with an increased risk of anomalies.
(Andrew M. Seaman, Reuters Health, February 2013)