GLENWOOD SPRINGS,Colo. State scientists say they haven't found any common underlying cause for birth defects reported in Garfield County.
Colorado's chief medical officer, Larry Wolk, announced Friday that the investigation looked at 22 rare anomalies detected by ultrasounds in Glenwood Springs late last year.
Some had suspected that the defects could be the result of oil and natural gas drilling in the county.
Epidemiologists looked at more than a dozen factors, including where the babies were conceived, drinking water sources, smoking and alcohol use and proximity to active oil and gas wells.
The majority of mothers lived more than 15 miles away from the nearest active drilling well and none lived in the same neighborhood.
Some mothers were from cites outside the county, including Meeker and Snowmass.