Childbirth and Labor Process

Introduction

• Full-term Pregnancy: Generally, 38-1/2 weeks.
• Childbirth/Parturition: Happens near the due date.
• Physiological Changes: Occur in preparation for childbirth.

Hormonal Changes Before Labor

• Progesterone: Levels drop around week 37; initially high to relax uterine muscle.
• Estrogen: Remains high, making uterine muscle sensitive to contractions.
• Oxytocin: Stimulates uterine contractions.
• False Labor/Braxton Hicks Contractions: Due to decreased progesterone.

Anatomical Overview

• Uterus and Pelvis: Uterus, placenta, amniotic sac, cervix, hip bones, birth canal.
• Fetal Drop: Fetus moves lower, affecting cervix.

Hormones and Pelvic Changes

• Relaxin: Secreted by placenta, loosens pelvic ligaments and pubic symphysis.
  • Accommodates growing fetus.
  • Eases childbirth by widening pelvic outlet.
• Cervical Dilation: Helps in labor.

Stages of Labor

• Stage 1: Cervical Dilation

  • Cervix needs to dilate to ~10 cm for vaginal birth.
  • Oxytocin and Prostaglandins: Cause uterine contractions and cervix softening.
  • Positive feedback loop for stronger contractions.
  • Mucus Plug: Discharge from the cervix.
  • Amniotic Sac Rupture: "Water breaking."
  • Active Labor: Starts at 4 cm dilation, progresses to 10 cm.

• Stage 2: Expulsion of the Baby

  • Starts when fetal head enters birth canal.
  • Uterus contracts rhythmically.
  • Skull bones of newborn compress for easier passage.
  • Crowning: When baby's head becomes visible.
  • Umbilical Cord: Cut post-delivery.

• Stage 3: Delivery of Afterbirth

  • Uterus ejects placenta and membranes.
  • Involution: Uterus contracts to shrink back to normal size.

Presentation and Delivery Methods

• Vertex Presentation: Head-first, most common.
• Breech Presentation: Less than 5%, feet or buttocks first.
  • Often leads to C-section recommendation.

Cesarean Section (C-section)

• Used when breech presentation or other risks occur.
• Involves incisions in abdomen and uterus.
• Slightly riskier than vaginal birth.

Conclusion

• Childbirth involves complex physiological and anatomical processes.
• Different stages ensure smooth delivery of the baby and afterbirth.
• Hormonal and structural changes play key roles in facilitating childbirth.