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

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.

3

Parturition

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.

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

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

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

Infection accounts for 14.9% of all maternal deaths

These deaths can be avoided with 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

15

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

16WHO 1999.

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 injury17

WHO 1999.

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

Bladder catheterization Operative delivery Oxytocin augmentation Pain control with systemic agents Pain control with epidural analgesia Continuous electronic fetal monitoring

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.

Lactation

• Hypothalamus releases PRH.• Anterior pituitary releases prolactin:

– Stimulates milk production.• Prolactin secretion primarily

controlled by PIH.• Oxytocin needed for “milk letdown.”

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.

Insert fig. 20.55

Milk-Ejection Reflex

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