Time of Oxytocin Initiation at 2nd Stage of Labor and Adverse Outcomes

Cesarean delivery (CD) is one of the most common surgeries performed worldwide. In the last few decades, its rate has steadily increased worldwide, leading to an increase in maternal morbidity and mortality compared to vaginal delivery (VD)1. In 2014, the American College of Obstetricians and Gynecologists (ACOG) and Society for Maternal Fetal Medicine (SMFM) published an Obstetric Care Consensus for safe prevention of primary cesarean delivery, allowing an additional hour of pushing during the 2nd stage of labor for both nulliparous and multiparous women before diagnosing prolonged 2nd of labor2-4.

Prolonged 2nd stage is especially common among nulliparous women5, and is defined as more than three hours of pushing6, or four hours for women with a regional anesthesia. Prolonged 2nd stage has been shown to be associated with maternal adverse outcomes, such as assisted-vaginal delivery, CD, and postpartum hemorrhage (PPH)7,8, and neonatal adverse outcomes such as low 5-minute Apgar score, and NICU admissions9.

Oxytocin is the primary and the most widely used pharmacological agent for induction and augmentation of labor10. Administrating oxytocin during labor is a common practice and is used to intensify contractions and decrease the chances of a non-progressive labor and associated adverse outcomes11,12. Despite its extensive use, there are several protocols which varies between different countries and obstetric wards. Likewise, there is no consensus regarding the duration or dosage of oxytocin infusion during labor, and especially during the 2nd stage of labor13.

The study will assess the optimal time initiation of Oxytocin during the 2nd stage of labor, and its association to mode of delivery, and adverse maternal and neonatal outcomes.

Inclusion criteria

• Singleton pregnancy
• Maternal age ≥ 18 years' old
• Oxytocin administration initiated or renewed during second stage of labor

Exclusion criteria

• Maternal age < 18 years' old
• Multiple gestation pregnancy
• Known fetal malformations
• Uterine scar