Causes of intrauterine fetal death are changing in recent years

To investigate, how causes of intrauterine fetal death (IUFD) have changed in recent years with the advancement of prenatal diagnosis at a single perinatal center in Japan. Medical records were retrospectively reviewed for all cases of IUFDs that occurred between 2001 and 2014. The most commonly associated causes of fetal deaths were compared between 2001-2007 and 2008-2014. The number of IUFD after 20 weeks' gestation/all deliveries in our center was 38/6878 cases (0.53%) in 2001-2007 and 35/7326 (0.48%) in 2008-2014. The leading cause of IUFD in 2001-2007 was fetal abnormalities (43.2%), the prevalence of which was only 8.6% in 2008-2014 (P<0.01). Meanwhile, the prevalence of umbilical cord abnormalities was relatively increased from 30.0% in 2001-2007 to 54.5% in 2008-2014 (P=0.06). In 2001-2007, chromosomal abnormalities were frequently observed (56% of IUFDs due to fetal abnormalities). Hyper-coiled cord (HCC) and umbilical ring constrictions were the most frequent cause of IUFD in both periods. The relatively decreased prevalence of IUFD due to velamentous cord insertion and umbilical cord entanglement, HCC and umbilical cord constriction was increased. The prevalence of IUFD due to fetal abnormalities was reduced, but IUFD associated with umbilical cord abnormalities tended to increase relatively.