1. The hormonal control of birth
© 2016 Paul Billiet ODWS

2. Birth
© 2016 Paul Billiet ODWS

3. The beginning of labour: (2 to 24 h before birth)
Pituitary Gland
Oxytocin stimulates
Myometrium
(Muscles of the uterus)
Irregular contractions 45s to 1 min
Pulls cervix open
Progesterone from the placenta
inhibits
Positive feedback
Cervix dilating
diameter 2 to 8 cm
Relaxin
stimulates
Cervix stretch receptors
© 2016 Paul Billiet ODWS

4. Delivery: 30 min to 2 hours before birth
Pituitary Gland
Oxytocin stimulates
Myometrium
Regular contractions 45s to 1 min every 5 min
Positive feedback
Cervix fully dilated
diameter 10 cm
Cervix and birth canal stretch receptors
Abdominal muscles
“bearing down”
© 2016 Paul Billiet ODWS

5. Afterbirth
The delivery of the placenta, amniotic sac and the rest of the umbilical cord
© 2016 Paul Billiet ODWS

6. Gestation v size
© 2016 Paul Billiet ODWS

7. Gestation v Size
© 2016 Paul Billiet ODWS