Rib fractures are common after motor vehicle collisions. The hormonal changes associated with pregnancy decrease the stiffness and increase the laxity of cartilage and tendons. The effect of these changes on injury mechanics is not completely understood.


To compare the incidences of chest wall injury following blunt thoracic trauma between pregnant and nonpregnant women.


The authors conducted a retrospective review of female patients seen at a level I trauma center from 2009 to 2017 after a motor vehicle collision. Patient characteristics were compared to determine if pregnancy affected the incidence of chest wall injury. Statistics were calculated with SPSS version 24 and are presented as mean (SD) or median (interquartile range).


In total, 1618 patients were identified. The incidence of rib/sternal fracture was significantly lower in pregnant patients (7.9% vs 15.2%, P = .047), but the incidence of intrathoracic injury was similar between the groups. Pregnant and nonpregnant patients with rib/sternal fractures had similar Injury Severity Score results (21 [13-27] vs 17 [11-22], P = .36), but pregnant patients without fractures had significantly lower scores (1 [0-5] vs 4 [1-9], P < .001).


Pregnant patients have a lower rate of rib fracture after a motor vehicle collision than nonpregnant patients. The difference in injury mechanics may be due to hormonal changes that increase elasticity and resistance to bony injury of the ribs. In pregnant trauma patients, intrathoracic injury without rib fracture should raise concerns about injury severity. A multicenter evaluation of these findings is needed.

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