Physiology of Normal Labour and Childbirth

1. Physiology of Normal Labour and Childbirth For you assessment you are required to revise those slides with white background. Slides with black ground would give you an idea about few practical aspects of childbirth and care of a woman in labour. http://www.youtube.com/watch?v=duPxBXN4qMg

2. Parturition • Estrogen in late pregnancy: • Stimulates production of oxytocin receptors in myometrium. • Produces receptors for prostaglandins. • Produces gap junctions between myometrium cells in uterus. • Factors responsible for initiation of labor are incompletely understood.

5. Parturition

7. Parturition • Fetal adrenal cortex: • Chain of events may be set in motion through CRH production. • Fetal adrenal zone secretes DHEAS, which travel from fetus and placenta. • Uterine contractions: • Oxytocin. • Prostaglandins.

9. Labour Pain • Variation in pain perception between individuals • Why do these different perceptions of pain exist • How do midwives respond to different expression of pain

10. Pain in Labour C-fibres • Uterine smooth muscle • A-delta • traction and pressure on the peritoneum, uterine ligaments, urethra, bladder, rectum, lumbosacral plexus, fascia and muscles of the pelvic floor

13. Partograph and Criteria for Active Labor • Label with patient identifying information • Note fetal heart rate, color of amniotic fluid, presence of moulding, contraction pattern, medications given • Plot cervical dilation • Alert line starts at 4 cm--from here, expect to dilate at rate of 1 cm/hour • Action line: If patient does not progress as above, action is required

14. Clean Delivery • Infection accounts for 14.9% of all maternal deaths • These deaths can be avoided with infection prevention practices

15. Infection prevention practices • Use disposable materials once and decontaminate reusable materials throughout labor and childbirth • Wear gloves during vaginal examination, during birth of newborn and when handling placenta • Wear protective clothing (shoes, apron, glasses) • Wash hands • Wash woman’s perineum with soap and water and keep it clean • Ensure that surface on which newborn is delivered is kept clean • High-level disinfect instruments, gauze and ties for cutting cord

16. Support of woman • Give woman as much information and explanation as she desires • Provide care in labor and childbirth at a level where woman feels safe and confident • Provide empathic support during labor and childbirth • Facilitate good communication between caregivers, the woman and her companions • Continuous empathetic and physical support is associated with shorter labor, less medication and epidural analgesia and fewer operative deliveries WHO 1999.

17. Best practices: last stage of labour • Active management of third stage for ALL women: • Oxytocin administration • Controlled cord traction • Uterine massage after delivery of the placenta to keep the uterus contracted • Routine examination of the placenta and membranes • 22% of maternal deaths caused by retained placenta • Routine examination of vagina and perineum for lacerations and injury WHO 1999.

18. Best Practices: Postpartum • Close monitoring and surveillance during first 6 hours postpartum • Parameters: • Blood pressure, pulse, vaginal bleeding, uterine hardness • Timing: • Every 15 minutes for 2 hours • Every 30 minutes for 1 hour • Every hour for 3 hours

19. Practices Used for Specific Clinical Indications • Bladder catheterization • Operative delivery • Oxytocin augmentation • Pain control with systemic agents • Pain control with epidural analgesia • Continuous electronic fetal monitoring

20. Best Practices: Labour and Childbirth • Use non-invasive, non-pharmacological methods of pain relief during labor (massage, relaxation techniques, etc.): • Less use of analgesia OR 0.68 (CI 0.58–0.79) • Fewer operative vaginal deliveries OR 0.73 (95% CI 0.62–0.88) • Less postpartum depression at 6 weeks OR 0.12 (CI 0.04–0.33) • Offer oral fluids throughout labor and childbirth Neilson 1998.

21. Lactation • Hypothalamus releases PRH. • Anterior pituitary releases prolactin: • Stimulates milk production. • Prolactin secretion primarily controlled by PIH. • Oxytocin needed for “milk letdown.”

22. Lactation • Mammary gland: • Lobules contain glandular alveoli that secrete milk of the lactating female. • Alveoli secrete milk into secondary tubule that converge to form mammary duct. • Ampulla: • Where milk accumulates during nursing. • Neuroendocrine reflex: • Act of nursing maintains high levels of prolactin. • Sucking may cause release of PRH.

23. Milk-Ejection Reflex Insert fig. 20.55

24. A question which will be certainly in my list of questions this year or next year • Write a short story about oxytocin. • This should include: • History of discovery of oxytocin • Its chemistry • Its physiological action in childbirth and its other physiological functions • Its uses in clinical practice