This study through to the pregnant woman blood concentrations of dexamethasone therapy after research, explore the pharmacokinetic data of dexamethasone in pregnant women, Chinese pregnant women dexamethasone pharmacokinetic model, provide a reference for the clinical use of dexamethasone dose, through the biomarkers of dexamethasone to promote fetal lung maturity and other metabolomics, It provides the basis for the effectiveness and safety study of dexamethasone.

This study was a single-center, open clinical study. Maternal blood, feces, umbilical venous blood, and placental tissue were collected from GW24-36 Chinese women with preterm labor treated with dexamethasone, excluding placental abruption, severe intrauterine bleeding, or women who met the exclusion criteria. The determination and implementation of dexamethasone treatment by clinicians are executed according to the guidelines, the sample collected in addition to collecting feces and an active medication before an initiative to collect blood after medication, the other is to pregnant women normal diagnosis and treatment after operation opportunity or placental blood collection way, this study does not interfere with the normal of maternal pregnancy, production, and diagnosis and treatment process. A total of 288 Chinese pregnant women with preterm preterm birth who required dexamethasone treatment were randomly divided into eight groups with 36 participants in each group. At admission, blood was retained for each group after biochemical or routine blood test and blood was abandoned once (2 mL). After that, subjects were treated with DEX (5 mg intramuscularization, Q12h, for 2 days, if there was still no delivery 7 days after the first drug administration, another course of treatment or treatment as prescribed by the doctor). During the study period, do not take any food or drugs (such as coffee, alcohol, hypoglycemic drugs and other drugs used with caution or prohibited by pregnant women) that may affect the safety of the fetus. 2 mL of venous blood was collected from each group at 0.5 h, 2 h, 4 h, 6 h, 12 h, 24 h, 36 h, 48 h after the first administration. Blood biochemical or blood routine waste blood at the last prenatal examination was collected in each group, and umbilical venous blood was collected postpartum. Placenta samples were collected postpartum. All samples will be tested for dexamethasone and its metabolite concentrations, pharmacodynamics and safety indicators, hormones and metabolomics. Neonatal development was evaluated by PEABODY score and Bailey Scale at 6 and 24 months postnatal.

Inclusion Criteria:

• Aged 20-40 (inclusive);
• Body mass Index (BMI) 18.5-27.9kg /m2 (inclusive)
• Single and twin pregnancy;
• Premature delivery at 24-36 weeks;
• No antibiotics, prebiotics or probiotics were used one month before feces collection (such as Bifidobacterium triplex live powder, Lactobacillus acidophilus tablet, compound Lactobacillus acidophilus tablet, Bacillus subtilis diplex live intestinal capsule, etc.);
• Preeclampsia patients accounted for about 1/10 of each group;
• Use dexamethasone I.M. 5mg Q12h regimen (or other dexamethasone administration regimen) to promote fetal lung maturation.

Exclusion Criteria:

• Ectopic pregnancy;
• Suffering from diabetes, fetal distress, serious infectious diseases (such as sepsis, septic shock), fever;
• Those who have taken glucocorticoid drugs within 2 weeks before joining the clinical trial;
• Those who took clindamycin during the study period;
• Congenital fetal malformation or fetal hypoxia in early pregnancy;
• Convulsive patients;
• HIV/HCV/ HEPATITIS A, drug abuse history;
• Suffering from chorioamnitis, endometritis;
• Placental abruption, severe intrauterine bleeding;
• Pregnant women whose cervical dilation is greater than or equal to 4 cm or whose cervical length is less than or equal to 20 mm by ultrasound examination;
• Pregnant women who took food or drugs during the study that might affect the safety of the fetus;
• Pregnant women participating in other clinical trials.

288 Chinese pregnant women with preterm prematurity requiring dexamethasone treatment.