Association between maternal dysglycaemia and adverse perinatal outcomes: A retrospective cohort study using a Japanese mother-infant-linked claims database

Claims-based perinatal studies in Japan are limited because normal pregnancies are not covered by health insurance. This study aimed to examine the association between maternal dysglycaemia and perinatal outcomes using a mother-infant-linked claims database. We conducted a retrospective cohort study using the JMDC Claims Database from April 2012 to March 2023. Singleton mother-infant pairs were presumed by family ID and categorised into six mutually exclusive claims-based categories: anti-diabetic prescriptions both before and during pregnancy with (Category 1) or without (Category 2) a pre-pregnancy type 1 diabetes code, prescriptions in prenatal period only (Category 3), prescriptions before pregnancy only (Category 4), a gestational diabetes (GDM) management-fee claim without anti-diabetic prescriptions (Category 5) and no identified claims-based indicator of dysglycaemia (Category 6). Outcomes included caesarean section, macrosomia, preterm birth, neonatal asphyxia, neonatal intensive care unit (NICU) admission and congenital malformations of the circulatory system. Among 115,113 presumed mother-infant pairs, 21.5% of mothers underwent caesarean section, with higher proportions in Categories 1 and 2 (40.6% and 48.3%). Highest point estimates were observed in Category 1 for most outcomes. Category 2 was associated with increased risks of caesarean section (adjusted risk ratio 2.04, 95% confidence interval 1.77-2.35), preterm birth (3.69, 2.57-5.28) and NICU admission (3.88, 3.02-4.99). Category 5 was positively associated with macrosomia (2.43, 1.64-3.62). Claims-based indicators of maternal dysglycaemia were associated with adverse perinatal outcomes. These findings suggest potential utility of mother-infant-linked claims data for Japanese perinatal monitoring, subject to further validation.