Babies of First Cousins Have Higher Risk of Death

April 8, 1999 - 0:0
WASHINGTON Babies whose parents are first cousins have nearly twice the risk of being stillborn, Norwegian researchers report. The finding was reported by Dr. Camilla Stoltenberg and colleagues at the National Institute of Public Health in Oslo, writing in the April issue of the American Journal of Public Health. They checked Norway's health registers for "consanguineous" marriages -- those between first cousins.

These are very rare in Norway, but much more common in other countries. They compared birth records for first-cousin couples to those of people not related at all. Marriages between second and third cousins were excluded. "For unrelated parents, the risk of early death (stillbirth plus infant death) for the subsequent sibling was 17 in 1,000 if the previous child survived," they wrote.

If an unrelated couple lost a baby at birth, the risk the next baby would be stillborn was 67 in 1,000, they wrote. But in first cousins, the risk of having a stillborn baby was 29 in 1,000, and rose to 116 in 1,000, or more than one in 10, if the previous baby had died. Although only 0.1 percent of ethnic Norwegians are married to their first cousins, the percentage in Pakistan is more than 49 percent, in Jordan it is 35 percent and in Lebanon it is 17 percent.

Such couples should be told of the risks, Stoltenberg's team said. "Consanguineous marriage has cultural and economic advantages, and knowledge of the advantages and risks associated with consanguinity is essential to decisions about public health measures," they noted. Because it increases the likelihood of the same faulty gene being passed on twice, inbreeding raises the risk of genetic diseases such as phenylketonuria, which can cause severe mental retardation if a person does not avoid certain proteins.

It is also suspected in the early deaths of babies. (Reuter)