Decongestant use in pregnant women linked to lower risk of preterm birth

Preterm birth -- deliveries at less than 37 weeks' gestation­ -- is the leading cause of infant morbidity and mortality in developed countries, but its causes remain largely unknown, said Rohini Hernandez, the study's lead author and a doctoral candidate in epidemiology at BUSPH. In the United States, the rate of preterm delivery has increased from 9.5 percent in 1981 to 12.3 percent in 2008.

"Maybe this can provide some clues as to how to prevent preterm delivery," Hernandez said. "The more we can learn about what could potentially cause preterm birth would help our understanding in how to stop it."

The study, published online ahead of print in the journal Birth Defects Research Part A: Clinical and Molecular Teratology, found that women who took decongestants in their second or third trimesters had a roughly 58 percent reduced risk of preterm delivery compared to women who didn't use decongestants during their pregnancy. (The finding was observed only for women without preeclampsia.) The authors cautioned, however, that the findings do not necessarily imply a cause and effect relationship.

Decongestants are one of the most frequently used over-the-counter medications by pregnant women. Many, however, choose to not take any medications during their pregnancy to prevent potential harm to the developing fetus, Hernandez said.

"Medication use is a major concern for pregnant women and generally, when medications are found to have effects on the fetus, they're usually found to have adverse effects," Hernandez said. "This was surprising in that a potentially beneficial effect was found.

The researchers analyzed data from 3,271 live-born births by Massachusetts women, obtained between January 1998 and September 2008 as part of the longstanding Birth Defects Study, conducted by Boston University's Slone Epidemiology Center.

Approximately 6 percent of the study population delivered preterm, the authors wrote. Of that, 4.2 percent took decongestants while 6.7 percent did not. The women who took decongestants tended to be older, white, married, highly educated and have higher incomes.

The authors' findings supporting those from a 2006 Swedish study that found a link between prescription decongestant use and preterm delivery. Yet Hernandez said more research is needed to see if there is an actual cause and effect relationship between decongestant use and preterm birth and if so, what element in the decongestant is producing this outcome.

Co-authors on the study include Allen Mitchell, MD, professor of epidemiology and director of the Slone Epidemiology Center, and Martha Werler, DSc, MPH, professor of epidemiology.