Introduction: There are very few population-based studies on the incidence of stroke in women of childbearing age, stratifying by stroke types and pregnancy-related periods.
Methods: We used an open cohort study design including all women aged 15-49 years from UK linked primary (Clinical Practice Research Datalink) and secondary (Hospital Episode Statistics) care records in 1997-2014. The exposure of our study was pregnancy resulting in a live or a stillbirth and associated antenatal and postpartum periods. The outcome of the study was the first ever stroke diagnosis, defined using ICD-10 codes (I60-I64, O22.5 and O87.3) or relevant Read codes, and classified as having ischaemic stroke (IS), intracerebral haemorrhage (ICH), subarachnoid haemorrhage (SAH) or unspecified. We calculated the absolute rates of stroke per 100,000 person-years and 95% confidence intervals (95%CI) for different exposure periods. We stratified the analysis by maternal age and types of stroke.
Results: Of 2,047,858 women, we identified 336,957 women with 453,776 deliveries. There were totally 2,526 women with a first incidence of stroke: IS 1,140 (45.1%), SAH 684 (27.1%), ICH 368 (14.6%) and unspecified 334 (13.2%). The overall incidence rate of stroke was 24.9 (95%CI 23.6-26.2) per 100,000 person-years in the non-pregnant period (IS 11.2 [10.4-12.1], ICH 3.6 [3.2-4.2], SAH 6.8 [6.2-7.5] and unspecified 3.3 [2.9-3.8]). The incidence was however higher around delivery (281.9 [141.6-561.2]) and in the first six weeks postpartum (43.8 [25.3-75.9]) and the rate ratios compared to the non-pregnant period after adjusting for age were 19.2 (9.6-38.3) and 3.0 (1.7-5.2) respectively.
Conclusions: Although the incidence of stroke for young women was relatively low, the incidence around delivery or in the early postpartum was significantly higher compared to other periods, regardless of maternal age.