Subclinical hypothyroidism is not associated with neonatal morbidity in women with gestational diabetes mellitus: a case–control study

Placental modifications observed in women with subclinical hypothyroidism (SCH) should be associated with altered fetal development in women with gestational diabetes mellitus (GDM) and worsen perinatal outcome. We aim to determine if SCH is associated with neonatal morbidity in women with GDM. A secondary analysis of data collected for a prospective population-based cohort study including all pregnant women with singleton pregnancies at diagnosis of GDM in a tertiary care university hospital. Thyroid-stimulating hormone and free thyroxine were measured at diagnosis of GDM. Perinatal outcome was compared between two groups-women with SCH and euthyroid. Neonatal morbidity was defined by at least one of the following criteria: preterm birth, macrosomia, shoulder dystocia, respiratory distress syndrome, 5-min Apgar score