Likelihood of Preterm Birth in Patients After Antenatal Corticosteroid Administration in Relation to Diagnosis and Confounding Risk Factors: A Retrospective Cohort Study

Background: In the case of threatened preterm birth (PTB) before the 34th week of pregnancy, the application of antenatal corticosteroids (ACSs) for the maturation of the fetal lung is a standard procedure in perinatal medicine. Common diagnoses for ACS use in pregnancy are the preterm rupture of membranes (PPROMs), placental bleeding, premature labor, preeclampsia, oligohydramnios, amniotic infection syndrome (AIS), and cervical insufficiency. The aim of this study was to investigate whether the current diagnosis, which results in ACS, and the patient's risk factors influence the risk of PTB events. Methods: The data of all affected women were extracted, who were hospitalized in 2016 due to a threatening PTB and administered corticosteroids in the German federal state Rhineland-Palatinate (n = 1544), so the study was conducted as a retrospective cohort trial. Frequency analyses, Friedman tests, Chi square tests, logistic regressions, Spearman correlation, and moderation analysis were performed to determine the Odds ratio (OR) for PTB in ACS patients in relation to diagnosis and risk factors. Results: Only 60% of all patients with PTB risk delivered prematurely, whereby patients with different diagnoses differ in terms of the PTB risk; the highest risk could be found in AIS (OR = 16.12) or preeclampsia (OR = 5.46). For prior PTB, stillbirth, or abortion, there is a moderation effect (based on the confounders), while multiple pregnancies influence the PTB risk irrespective of diagnosis (OR = 6.45). In the whole collective, the OR for PTB was 6.6 in relation to all pregnant women in Germany. Conclusions: A higher risk of PTB could be found in patients with a diagnosis of AIS, preeclampsia, as well as in multiple pregnancies. Prior PTB, stillbirth, or abortion act as a relevant confounder.