Pregnancy-related deaths due to pulmonary embolism in Sweden

Background. The objective of this study was to report deaths from amniotic fluid embolism (AFE) and pregnancy-related venous thromboembolism (VTE), to study contributing factors, and to analyse mortality trends. Methods. Using the Swedish Cause of Death Register (CDR), we identified all women aged 15 - 44, who died during 1990 - 1999, with VTE or AFE coded as the underlying or contributory cause of death. We scrutinised medical records, and women who had died during pregnancy or within 6 weeks of terminated pregnancy were included. We also used data from the Medical Birth Register (MBR) on incident and fatal cases. Mortality data from the 1970s and 1980s were based on previous studies, in which cases were identified through register linkage ( CDR and MBR). Results. Five women died of AFE and 10 of VTE - 6 of them in early pregnancy - during the 1990s. Five of the cases were not registered as maternal deaths. Only 4 cases were reported as pregnancy-related deaths from pulmonary embolism ( PE). Cesarean section/surgery without thromboprophylaxis, overweight, severe intercurrent disease, delays in seeking health care, and verbal miscommunication were contributing factors in the VTE cases. VTE mortality rates ( pregnancy > 28 weeks and/or a registered birth) were 1.0 (0.5 - 1.8), 0.8 (0.3 - 1.6), and 0.4 (0.1 - 1.0) per 100,000 live births during the 1970s, 1980s and 1990s, respectively; the corresponding respective figures for AFE were 1.0 ( 0.5 - 1.8), 1.1 ( 0.6 - 2.1), and 0.5 (0.2 - 1.1) per 100,000 live births. The case fatality rate for VTE decreased from 4.5% in the 1970s, to 0.6% in the 1990s, paralleled with quadrupled incidence. The case fatality rate for AFE was unaltered and high, around 45%, during those 3 decades. Conclusions. Mortality from pregnancy-related PE in Sweden is in the lowest range ever reported, and shows a downward trend during the 1990s, with a shift towards early pregnancy. In order to monitor mortality trends, death certificate quality must improve, and registers must be linked routinely.