Impact of new gestational diabetes mellitus criteria on stillbirth: A regional population-based study in Japan

Aim The aim of this study was to determine whether the new gestational diabetes mellitus (GDM) criteria increase the prevalence of diabetes‐mellitus‐related stillbirths by using a regional population‐based approach. Material and Methods A retrospective, population‐based study was conducted to assess 114 036 deliveries from 2000 to 2010 in Miyazaki, Japan. During this period 318 stillbirths occurred after 22 weeks of gestation. Of these cases, 236 were examined to determine the cause of death. The remaining 82 cases were not fully investigated. In particular, we investigated the prevalence of pregestational diabetes mellitus and GDM among the stillbirths. We also applied new GDM criteria to evaluate the impact of these factors on stillbirth. Results Of the 236 stillbirths, 47% were due to an explainable cause. Application of previous criteria indicated two cases of pregestational diabetes mellitus and three GDM cases in the remaining unexplained stillbirths. By applying new GDM criteria, the GDM count increased to 17. Conclusions In an unselected population in southern Japan, the application of new GDM criteria resulted in a 5.7‐fold increase (from 2.4% [3/126] to 13.5% [17/126]) in the number of GDM cases in unexplained stillbirths. Even in women with a mild degree of GDM, proper management of both mother and fetus could reduce the number of unexplained stillbirths.