Universal Cervical Length Screening and Antenatal Corticosteroid Timing

To evaluate the relationship between universal transvaginal screening for short cervical length in the second trimester and the timing of antenatal corticosteroids.

We performed a retrospective cohort study of patients with nonanomalous singleton gestations and spontaneous preterm birth between 24 and 34 weeks of gestation after the initiation of a universal transvaginal cervical length screening program between October 2012 and August 2015. Our primary outcome was antenatal corticosteroid administration to a delivery interval of fewer than 7 days. Secondary outcomes were delivery 24 hours to 7 days after the initial steroid injection, steroid administration to delivery interval, neonatal survival, neonatal intensive care unit length of stay, and respiratory distress syndrome. Multivariable logistic regression was used to estimate the association between antenatal corticosteroid timing and the diagnosis of a short cervix adjusted for potential confounders.

Among 266 eligible patients, 69 with a short cervical length and 197 without a short cervical length were identified. There were no statistically significant differences in baseline characteristics between the groups. During the study period, 64 of 69 (92.8%) of patients with a short cervix and 176 of 197 (89.3%) without a short cervix received at least one steroid injection before delivery (P=.411). Steroids were given within 7 days of delivery in 33 of 69 (47.8) patients with a short cervix compared with 126 of 197 (64%) patients in the no short cervix group (P=.015; adjusted odds ratio 0.51, 95% confidence interval 0.29-0.9). Median interval between steroid administration and delivery was 8 days in patients diagnosed with a short cervix compared with 3 days for those without a short cervical length (P<.001).

Patients identified as having a short cervical length by universal transvaginal ultrasound screening were at greater risk of delivering more than 7 days after the initiation of corticosteroids for fetal lung maturation compared with women without a short cervical length.