Infant births during the internal night are at increased risk for operative delivery and NICU admission.

PURPOSE: The purpose of the present study was to compare neonatal morbidity between night and the rest of day and investigate potential differences of birth outcomes during the internal night.
METHODS: We conducted a retrospective study based on maternal and neonatal data of period 2004-2007, enrolling exclusively spontaneous deliveries of term (≥ 37 weeks), singleton pregnancies with cephalic presentation that were in labor. Time of day was divided into the night-shift period, from 11.00 p.m. to 7.00 a.m. (period 1) and the rest-of-day period, from 7.00 a.m. to 11.00 p.m. (period 2). The night-shift period was further sub-divided into period 1a (11.00 p.m.-3.00 a.m.) and period 1b (3.00 a.m.-7.00 a.m.). Epidemiological and obstetric characteristics as well as neonatal outcomes were initially compared between periods 1 and 2 and thereafter between sub-periods 1a and 1b.
RESULTS: There were 3,055 cases with complete data meeting our inclusion criteria, of which 871 (28.5%) were delivered during period 1 and 2,184 (71.5%) during period 2. Furthermore, 51.3% of night-born infants were delivered during period 1a and the remaining 48.7% during period 1b. All examined parameters were not significantly different between periods 1 and 2. Analyzing night internally, the rate of emergent CS was significantly higher for period 1a (13.2%), compared with period 1b (4%). Furthermore, incidence of NICU admission was significantly higher for the first half of the night-shift period (2.7%) compared to the relative of the second half (0.5%).
CONCLUSIONS: Neonatal morbidity was comparable between night-shift and rest-of-day periods, but the rates of emergent CS and NICU admission were significantly increased in the first half of the night-shift period (11.00 p.m.-3.00 a.m.).