ANHB2212 Final: ANHB2212 EXAM NOTES: Childbirth
3 Jun 2018
School
Course
Professor
Childbirth
Stages of Labour:
• Exact beginning of labour is not clear
• First stage → effacement of cervix
o Longest stage of labour → 8 hours
o Foetal head pressing on cervix stretches it and stimulates uterine
muscle contraction
o Presses head down harder → more stretching → more contraction
→ mechanical induction
o Before cervix can open it must thin out → efface
o Braxton-Hicks contractions → help begin effacing cervix before
labour begins
o After cervix is fully effaced, it begins to open → needs to be open to
10cm
o Hormonal stimulants
▪ Oxytocin
▪ Prostaglandin
▪ Oestrogen/progesterone
• Second stage → birth
o Takes less than an hour
o Mother uses diaphragm and abdominal muscles to push
o Usually rest of body is born rapidly after the head
o Urge to bear down expels foetus → 5-10 minutes if uncomplicated
• Third stage → afterbirth
o Uterus contracts to smaller size
o Sheering effect causes separation of placenta
o Placenta is normally delivered soon after → 10-45 minutes
o Placental site bleeds → ~ 350mL
o Empty uterus contracts to a tight ball → palpable and massage
able
o Endometrial vessels are shut down by smooth muscle loops
• Postpartum period → involution of uterus
o Uterus quickly returns to its non-pregnant state
o First 4-5 weeks, women frequently have strong uterine
contractions
o Uterus is ½ its postpartum weight after one week
o Nonpregnant size returns after 4 weeks
o Oxytocin → increases contractility of uterine muscles → released
through breastfeeding
o Lactation suppresses ostrogen and progesterone
Foetal Point of View:
• Stations of labour
o Pelvic inlet above → -5
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