Normal delivery
Children that are born between the 36th and 39th week (38 and 41 weeks after the LMP) are considered as being normal deliveries. Statistically, only 2/3 of all children are born within the 3 weeks around the calculated date of birth and around 80 % within a month around the predicted date of birth.
Giving birth proceeds in three periods:
- Dilatation period
- Expulsion or press period (subdivided into 4 phases)
- After-birth period
During delivery the infantile head has to conform to the various pelvic sections. In the expulsion period the first 3 phases describe the development of the head while phase 4 that of the shoulders, whereby the head rotates 90° back again.
(frontal view)
(from below)
The head, which is still "floating", sinks into the minor pelvis, in that the biparietal diameter conforms to the pelvic opening and is there fixated. In the view from below the two fontanels appear at the same height.
(frontal view)
(from below)
While the baby is pushed further down by the contractions of the uterus wall, a forward bending of the head occurs. In this phase only the smaller (rear) fontanel can be felt. The head bends forward so the baby can pass through the birth canal with the smaller suboccipito-bregma diameter.
Fig. 17(frontal view)
(from below)
In the third phase the baby turns completely with the back towards the front and the baby's neck arrives at the mother's symphysis so it can finally leave the birth canal with a subsequent stretch.