A Clinical Pharmacological Study of Dose Halving of Dexamethasone in Pregnant Women With Preterm Labour With Preterm Birth at Greater Than or Equal to 34 Gestational Weeks (34GW+)

Two studies will be conducted both of which are single-centre, open clinical studies. It is proposed to collect maternal blood, umbilical vein blood and placental tissue from pregnant women treated with dexamethasone, which excludes early placental detachment, use of surfactant, severe intrauterine haemorrhage, or pregnant women who meet the conditions of the exclusion criteria. Determination and implementation of dexamethasone treatment regimen will be carried out by clinicians in accordance with the treatment guidelines, and the collection of samples will be carried out in the form of opportunistic blood sampling or placenta collection after normal diagnostic and therapeutic operations of pregnant women except for 2 active collections of blood after dosing; this study will not interfere with the normal maternal pregnancy, labour and diagnostic and therapeutic processes. Half-dose study: A total of 24 Chinese pregnant subjects with 34+0-35+6 GW requiring dexamethasone treatment for preterm labour with preterm prematurity in China were planned to be enrolled in this study. A total of 12 subjects receiving 5 mg dexamethasone (intramuscular injection, q12h, 4 doses) were enrolled in the full-dose group; 12 subjects receiving 2.5 mg dexamethasone (intramuscular injection, q12h, 4 doses) were enrolled in the half-dose group. EXPLORATORY STUDY: This study was planned to enrol 24 pregnant women with 34+0-38+6 GW preterm labour with confirmed gestational diabetes mellitus (GDM) or diabetes mellitus in combination with pregnancy in a dose exploratory study in this population. A total of 12 subjects were enrolled in the full-dose group to receive 5 mg dexamethasone (intramuscular injection, q12h, 4 doses) and 12 subjects were enrolled in the half-dose group to receive 2.5 mg dexamethasone (intramuscular injection, q12h, 4 doses).