Does chlorination lead to miscarriage?

• Position: Pregnancy

Fears that chemical by-products resulting from purifying drinking water with chlorine boost the chances that pregnant women will miscarry are not supported by the results of a major study conducted by the University of North Carolina at Chapel Hill.

"We think our new work should be an important contribution to policy studies," contends David A. Savitz of the School of Public Health. "While it is not the final answer, what we found is largely reassuring relative to what had come before. The vast majority of the U.S. population is living with these exposures to drinking water by-products. If they clearly increased women's miscarriage rates, that would be a very big, very expensive problem to solve."

Scientists selected and repeatedly tested disinfection by-products in three properly functioning water purification facilities, including one with moderate levels of chlorination, one with moderate levels of bromination, and one with low levels of both. None of the utilities was selected because of water quality or health problems. Thousands of women then were recruited in the three areas who were planning a pregnancy or who had been pregnant for...