Preterm birth (PTB) is defined as birth before 37 completed weeks of gestation, which occurs in approximately 10% of all pregnancies [1]. PTB causes about 70% of all neonatal deaths of nonanomalous infants, as well as neonatal morbidities including respiratory distress syndrome, intraventricular hemorrhage, necrotizing enterocolitis, bronchopulmonary dysplasia and long-term complications such as cerebral palsy [2,3]. The PTB rate has risen worldwide, and in South Korea, the PTB rate has also risen from 4.3% in 1995 to 10% in 2003 [1,4]. There are many known risk factors for PTB, but one of the most ObjectiveTo evaluate whether the administration of vaginal natural micronized progesterone is associated with reduction of recurrent preterm birth (PTB) in women with prior history of spontaneous PTB. MethodsWe retrospectively evaluated the obstetric and neonatal outcomes of all women with history of spontaneous PTB that delivered from January 2008 through April 2012. Spontaneous PTB was defined as PTB before 37 weeks of gestation due to spontaneous preterm labor or preterm premature rupture of membranes. Pregnancies with multiple gestation and those who received cerclage operation during previous or current pregnancy were excluded. Patients in the progesterone group were instructed to selfadminister 100 or 200 mg vaginal micronized natural progesterone capsule. We evaluated the difference in recurrent PTB rate between the progesterone group (n = 73) and the non-user group (n = 158). ResultsThe incidence of recurrent spontaneous PTB before 37 weeks' gestation was significantly lower in the progesterone group than the non-user group (21.9% vs. 43.0%, P=0.002). Multivariate analysis showed that progesterone therapy was associated with a decrease in the incidence of recurrent PTB before 37 weeks' gestation (odds ratio, 0.382; 95% confidence interval, 0.169-0.863; P=0.021) independent of confounding variables. ConclusionMicronized vaginal progesterone supplement therapy was associated with a reduction of recurrent PTB risk in women with previous spontaneous PTB history.

ObjectiveTo investigate the effects of antenatal corticosteroid (ACS) on incidence of neonatal respiratory distress syndrome (RDS) according to maternal body mass index (BMI). MethodsWe retrospectively reviewed the medical records of 715 singleton pregnant women who delivered between 24+0 and 34+0 weeks of gestation, from January 1996 to December 2006. Subjects were categorized into three groups according to ACS exposure: a nonuser group (n = 244), a single-course group (n = 377) and a multiple-course group (n = 94). Subjects were re-categorized into three groups according to maternal BMI at admission: group 1 (BMI < 23.0 kg/m 2 , n = 234), group 2 (BMI 23.0-24.9 kg/m 2 , n = 166) and group 3 (BMI ≥ 25.0 kg/m 2 , n = 315). Univariate and multiple logistic regression analyses were used for the statistical analysis. ResultsOverall, the incidence of RDS was signifi cantly lower in ACS-user groups than the non-user group, with lowest incidence in the multiple-course group (non-user vs. single-course vs. multiple-course: 44.3% vs. 41.1% vs. 11.7%, P < 0.001). The incidence of RDS was not different among the three BMI groups. Multiple logistic regression analysis showed that single-and multiple-course of ACS was signifi cantly associated with reduced incidence of RDS: single-course, odds ratio (OR) 0.593, 95% confi dence interval (CI) 0.373, 0.942; multiple-course, OR 0.085, 95% CI 0.034, 0.213. However, maternal BMI was not associated with reduced incidence of RDS with different ACS-courses (P for interaction = 0.690). ConclusionACS therapy, especially when multiple-course was used, was signifi cantly associated with reduced incidence of RDS, but maternal BMI did not infl uence its effectiveness.