# What Is the Most Dangerous Time of Birth for Uncomplicated First-Time Mothers and Their Neonates in a Tertiary Obstetric Center?

## TL;DR

This study examines the most dangerous times for birth among first-time mothers and their babies in a hospital setting.

## Contribution

The study identifies specific times of day and days of the week with higher fetal distress indicators in first-time mothers.

## Key findings

- The highest probability of low umbilical artery pH occurred on Friday between 2:00 and 4:00 PM.
- Base excess below -12 was most frequent on Sunday between 4:00 and 6:00 AM.
- Fetal blood analysis was less frequent on weekends, but no increased neonatal asphyxia was observed.

## Abstract

Whether the timing of birth affects fetal or maternal outcomes is still controversial. Compared with multiparae, primiparae are a special obstetric group that are more likely to develop labor abnormalities that require intervention. The aim of this study was to investigate the time of delivery and perinatal morbidity with a focus on uncomplicated but first-time pregnancies.

This retrospective study analyzed all births of uncomplicated first-time mothers who intended vaginal delivery. The delivery times were clustered into 2-h intervals and by day of the week. A 5-min Apgar score ≤ 7, an umbilical artery pH value < 7.10, and BE > − 12 were defined as surrogate markers for perinatal morbidity. Other markers examined included the occurrence of a pathological cardiotocogram, the performance of fetal blood analysis via scalp sampling, admission to the neonatal intensive care unit (NICU), the mode of delivery, or the occurrence of labor arrest.

A total of 586 women who intended vaginal delivery were analyzed. The distribution of timepoints of birth divided into 2-h intervals corresponded to a normal distribution (p = 0.97). The probability of having an arterial umbilical pH value < 7.1 was highest on Friday between 2:00 and 4:00 PM (p = 0.035). A base excess below − 12 was most frequent on Sunday between 4:00 and 6:00 AM (p = 0.027). Fetal blood analysis via scalp sampling was performed less frequently than expected on the weekend (Saturday p = 0.031; Sunday p = 0.046), whereas the distribution of mode of delivery did not differ across the investigated periods.

We detected timepoints when laboratory signs of increased fetal distress were more frequent; although there was no difference in peripartal monitoring, the decision to perform a scalp blood gas analysis or the mode of delivery changed during these periods. On weekends, fetal blood analysis via scalp sampling was carried out less frequently than expected. An increased rate of severe asphyxia or a worse 5-min APGAR was not observed in the neonates at any timepoint. Primiparae should not be underestimated as a supposedly uncomplicated group, as they can present a particular obstetric challenge.