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Labor and delivery progress through three distinct stages: first stage (early, active, and transition phases with cervical dilation), second stage (pushing and birth of baby), and third stage (delivery of placenta). Each stage has characteristic duration, physical changes, and management considerations that guide clinical decision-making. Understanding these stages helps healthcare providers monitor progress, identify complications, and provide appropriate interventions.
Labor is initiated by complex hormonal interactions involving oxytocin, prostaglandins, and fetal signals that trigger uterine contractions and cervical ripening. The first stage involves progressive cervical effacement and dilation from 0-10 cm through coordinated uterine contractions. The second stage requires maternal pushing efforts combined with uterine contractions to facilitate fetal descent through the birth canal, while the third stage involves placental separation through continued uterine contractions and retraction.
Monitoring each stage allows clinicians to assess normal progression versus potential complications such as prolonged labor, fetal distress, or retained placenta. First stage duration varies significantly (8-20 hours for nulliparous women, 5-12 hours for multiparous), requiring assessment of contraction patterns, cervical change, and fetal heart rate. Second stage monitoring focuses on fetal descent, maternal vital signs, and signs of complications like shoulder dystocia, while third stage management includes monitoring for complete placental delivery and postpartum hemorrhage prevention.
Key imaging focus: Nodular liver surface, caudate hypertrophy, ascites, portal hypertension signs, varices