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The US is experiencing a baby boom of twins, triplets and other multiple
births. The National Center for Health Statistics near Washington DC has
examined birth certificates from 1980 to 1997 and found that the number of twin
births has grown by 52 per cent. Birth rates of triplets and larger multiples
more than quadrupled, while single births were up by only 6 per cent.
Researchers attribute the explosion to the trend in older mothers—who are
naturally more likely to have multiple births—and to increasing use of
fertility drugs.