An assessment of the impact of pregnancy on trauma mortality

In the United States, trauma is the leading cause of maternal mortality and an important source of maternal morbidity. Few studies have compared outcomes in injured pregnant women to their nonpregnant counterparts. Some clinical literature regarding hormonal influences on outcomes after trauma suggests a survival advantage in premenopausal women with higher estrogen levels. Given this, as well as possible outcome differences as a result of physiologic changes that occur during pregnancy, we tested the hypothesis that pregnant women have different outcomes after trauma compared with similarly injured nonpregnant women in the same age groups.

We used data derived from 1.46 million patients listed in The National Trauma Data Bank from 2001 to 2005, to query all injured patients between ages 12 and 49 years inclusive, and divided them into 2 comparison groups: nonpregnant and pregnant women. We compared differences in outcome after trauma between pregnant and nonpregnant women. Because the number of pregnant women was small in comparison to the number of nonpregnant women, multivariate analysis after 1:3 (pregnant:nonpregnant) matching was attempted.

Crude mortality rate comparisons and unadjusted logistic regression analyses both before and after matching data reveal lower mortality rates in pregnant women. Multivariate logistic regression analyses both before and after matching data also reveal lower mortality rates in pregnant women; but this is statistically significant (P = .01) only after matching data.

Among women of similar age groups who are equivalently injured, those who are pregnant exhibit lower mortality. These findings suggest that hormonal and physiologic differences during the gestation period may play a role in outcomes following trauma in pregnant women.