Analysis of preventability of stroke-related maternal death from the nationwide registration system of maternal deaths in Japan

The number of stroke-related maternal deaths is increasing in Japan. We investigated methods to reduce maternal death from stroke.We analyzed stroke-related maternal deaths in Japan reported to the Committee of the Ministry of Health, Labor, and Welfare from 2010 to 2014 inclusive.A total of 35 cases were identified. The median maternal age was 35 years (range 22-45) and the incidence of stoke in women ≥40 was seven-fold higher than in34. Etiologies were pregnancy induced hypertension in 16, subarachnoid hemorrhage in seven, cerebral infarction in three, arteriovenous malformation in two, Moyamoya disease in one, and origin unknown cerebral hemorrhage in six. These cases occurred in antepartum 43%, in postpartum 31%, and in intrapartum 26%. 23 cases were deemed non-preventable and 12 cases preventable. Possible preventable factors occurred antepartum in 23, postpartum in seven, and intrapartum in six. Preventable features included inadequate hypertension control (33%), presenting too late for termination of pregnancy (14%), delayed hospitalization (11%), and delayed maternal transfer (11%).A total of 90% of strokes were hemorrhagic, and older mothers (≥ 40) were most at risk. Most possible preventable factors occurred antepartum, and improved control of hypertension and earlier termination would help to reduce maternal death from stroke.