Abstract

Background: There is a small but significant higher risk to both women and newborns as the length of second stage labor increases. Higher risks to women include intensive care unit (ICU) admission, postpartum hemorrhage, episiotomy, 3rd or 4th degree perineal laceration, prolonged hospital stay, chorioamnionitis, and endometritis. Newborn risks include asphyxia, neonatal intensive care unit (NICU) admissions, sepsis, seizures, and low apgar scores.

Factors associated with prolonged second stage labor are poorly understood, and research has largely focused on the effect of obstetrical interventions such as labor augmentation and use of epidural analgesia, with little focus on physiologic birth.

The goal of the current research was to determine whether there were relationships between a broad variety of demographic, health, pregnancy, and labor factors and prolonged second stage labor in a population of healthy women experiencing physiologic birth.

Methods: This was a retrospective analysis of de-identified client-level data collected in the American Association of Birth Centers Perinatal Data Registry (PDR), including more than 34,000 pairs of women and newborns who began labor in freestanding birth centers between 2007 and 2016. Univariable relationships of demographic, health, pregnancy, and labor factors with prolonged second stage labor were explored. Multivariable logistic regression modeling was used to determine which factors had independent associations with prolonged second stage labor.

Results: The sample consisted of 1671 primiparous women and 16,137 multiparous women. The second stage of labor exceeded parameters for prolonged in 2.1% of first labors and 6.6% of subsequent labors. In multivariable analysis, only birth weight was positively associated with prolonged second stage of labor for primiparous people, and malposition, birth weight, narcotic analgesia and use of nitrous oxide were independently associated with prolonged second stage for multiparous people. Greater maternal age and greater maternal body mass index were negatively associated with prolonged second stage for multiparous people.

Conclusions: Factors associated with prolonged second stage of labor in freestanding birth centers largely mirrored those found in births occurring in hospital settings. Anticipating complications helps midwives make decisions about appropriate birth site and prepare for maternal and newborn complications from prolonged second stage of labor.

Keywords: Labor, Second stage, labor complications