The temporal link between prenatal steroid therapy and labor

Prematurity has been one of the greatest challenges faced by perinatal medicine for many years. The recommended therapy for women with threatened preterm labor at 24 to 34 weeks' gestation is a single course of glucocorticoids. The greatest benefits have been proven when labor occurs at least 24 hours, but no later than 7 days after steroid administration. Applied treatment is not without influence on neonates' development.

The aim of this study is to analyze the time between the administration of a course of glucocorticoids to patients with threatened preterm labor between 24 and 34 weeks of gestation and labor.

459 deliveries by patients between 24 and 34 weeks' gestation who had received betamethasone (two 12 mg doses) or dexamethasone (four 6 mg doses) were analyzed. Their indications for glucocorticoid therapy were divided into four categories: the signs of threatened preterm labor, premature rupture of membranes, iatrogenic prematurity and cervical incompetence. The neonates (n=530) were divided into two main groups: group 1 of those born within the first 7 days (n1=127) and group 2 of those born more than 7 days (n2=403) after the glucocorticoids therapy. Statistical analysis was performed using the Statistica 13.3 software with calculations performed using the Mann- Whitney U and χ2 tests, assuming the level of statistical significance of <0.05 (p<0.05).

The neonates born within the first 7 days after the glucocorticoid therapy accounted for 23.96% (127 children). The average time of delay between the course of glucocorticoids and labor was 33 days, with the longest interval being 116 days. The most common indications for glucocorticoids were iatrogenic causes in group 1 (35.40%) and the signs of threatened preterm labor (67.63%) in group 2.

The percentage of births at the recommended time after steroidotherapy (not later than 7 days) was lower than expected. The prenatal steroid therapy qualification methods, should be reanalyzed, especially when signs of preterm labor are observed.