Background and Purpose: Pregnancy is a risk factor for stroke. The mechanisms of stroke in pregnancy have not been well established. Cervical artery dissection may be one such mechanism, but it is unclear whether pregnancy is a risk factor for cervical artery dissection. Methods: We performed a cohort-crossover analysis using administrative claims data from all hospitalizations and emergency department visits involving nonfederal acute care hospitals in NY and FL between 2005-2015. We identified women ≥12 years old who were hospitalized for labor and delivery. Our outcome was cervical artery dissection, defined as carotid or vertebral artery dissection. We defined the period of risk as 6 months antepartum through 3 months postpartum. We compared each patient’s risk of dissection during this time period versus the corresponding 270-day period exactly 1 year later. Conditional Poisson models with robust standard errors were used to calculate incidence risk ratios (IRRs). Results: We identified 4,193,417 pregnancies among 3,061,413 women during our study period. There were 52 cases of cervical artery dissection during the peripartum period and 24 cases during the control period 1 year later. The incidence of cervical artery dissection was 12 (95% CI, 10-17) per million pregnancies versus 6 (95% CI, 4-9) per million patients during the control period 1 year later (IRR, 2.2; 95% CI, 1.3-3.5). Our findings were similar when we limited our outcome to cervical artery dissections complicated by ischemic stroke (IRR, 2.3; 95% CI, 1.1-5.1). Secondary analyses suggested that the heightened risk occurred in the peripartum and postpartum period (IRR,5.5; 95% CI, 2.6-11.7), not the antepartum period (IRR, 0.5; 95% CI, 0.2-1.2). Conclusions: In a large, population-based sample of women, pregnancy was associated with an increased risk of cervical artery dissection. This increased risk appeared to be limited to the peripartum and postpartum period.