The babies have not been named yet, said Dr. Harold Henry, the hospital's chief of maternal and fetal medicine.

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At the Cleveland Clinic, doctors perform 50% fewer invasive procedures, thanks to the testing advances, said Jeff Chapa, section head of obstetrics and maternal-fetal medicine.

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But Dr Clare Tower, consultant in obstetrics and fetal maternal medicine, at St Mary's Hospital, Manchester, stressed that women who have had the occasional alcoholic drink in pregnancy should not be overly alarmed by the findings.

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