Effects of ACS in Twin With LPB: Study Protocol for a RCT

Inclusion Criteria: * (1) Age over 18 years * (2) Twin pregnant women at 34weeks 0days to 36weeks 5days of gestation * (3) At risk for preterm birth such as preterm labor, preterm prematrue rupture of membrane or maternal-fetal indications that need preterm delivery. Preterm labor is defined as regular uterine contractions with or without the following symptoms; pelvic pressure, backache, increased vaginal discharge, menstrual-like cramps, bleeding/show, cervical changes * (4) Availability of written informed consent. Exclusion Criteria: * (1) Gestational age before 34weeks 0days or after 36weeks 6days * (2) Lethal major fetal anomaly, fetal distress or fetal death in utero * (3) Expected to deliver within 12 hours; for example, advanced cervical dilatation (\>8cm) in preterm labor or active phase labor (cervical dilatation\>4cm) in preterm premature rupture of membranes * (4) History of a previous administration of ACS before 34weeks of gestation for fetal lung maturation * (5) Administration of systemic steroid for medical indications * (6)Diagnosis of clinical chorioamnionitis Fever \>37.8 and the presence of two more following conditions: uterine tenderness, foul-odored vaginal discharge, maternal leukocytosis(\>1500), maternal tachycardia(\>100) or fetal tachycardia(\>160)