The Physiological Process of Labor and Delivery
Stages of Labor
- First Stage: This stage begins with the onset of regular uterine contractions and ends when the cervix is fully dilated (10 centimeters). It's subdivided into:
- Latent Phase: Early, irregular contractions causing gradual cervical effacement and dilation to 3-4 cm.
- Active Phase: More frequent and intense contractions leading to more rapid cervical dilation, typically from 4 cm to 7 cm.
- Transition Phase: The most intense phase, characterized by strong, frequent contractions and cervical dilation from 7 cm to full dilation.
- Second Stage: Begins with full cervical dilation and ends with the birth of the infant. This stage involves active maternal pushing efforts coordinated with uterine contractions.
- Third Stage: Begins immediately after the birth of the infant and ends with the expulsion of the placenta and membranes.
- Fourth Stage: The immediate postpartum period, typically lasting one to two hours, during which physiological adjustments occur, and the mother is closely monitored.
Hormonal Influences
Hormones play a crucial role in initiating and maintaining labor. Oxytocin, produced by the pituitary gland, stimulates uterine contractions. Prostaglandins contribute to cervical ripening and uterine contractions. Relaxin helps to loosen ligaments and joints in the pelvis.
Physiological Changes in the Mother
During labor, the mother experiences numerous physiological changes, including:
- Increased heart rate and blood pressure.
- Changes in respiratory rate and pattern.
- Shifting fluid and electrolyte balance.
- Pain and discomfort due to uterine contractions and stretching of tissues.
Fetal Adaptations
The fetus undergoes several adaptations during labor and delivery:
- Changes in heart rate patterns that are monitored to assess fetal well-being.
- Passage through the birth canal involving molding of the skull bones.
- Initiation of breathing shortly after birth.
Potential Complications
Labor and delivery can be associated with potential complications for both the mother and the fetus, including:
- Prolonged or arrested labor.
- Fetal distress.
- Postpartum hemorrhage.
- Infection.