Different meanings or significance of meaning are attached to the word “injury,” but it may be thought of as harm caused not necessarily by trauma, not necessarily with intention. A birth injury is harm that occurs to the fetus about to leave his mother and become a child. The harm may be by force in which case it could be called birth trauma, or it may occur as a result of non-traumatic causes. Birth injuries may therefore be considered either by chronology (when they occur in terms of the pregnancy and delivery), etiology (causation), or by the result (effect).
Placental anomalies such as placenta praevia or abruption (sudden separation) may affect the fetus as a result of diminished oxygen supply. Premature rupture of membranes might be followed by infection. A recognized placenta praevia may indicate a C section or judgement might be otherwise; an abruption generally calls for an immediate section.
The fetus is supposed to lie head down, with the face to the sacrum at the time of delivery. Any other position increases the breadth of the body passing through the birth canal and increases the risk of injury. Abnormality of the position of the fetus in the uterus may be recognized traditionally by physical examination, but today is backed by ultrasound examination, which unlike X-rays is believed harmless and safe to repeat as often as indicated. It is a matter of judgement whether an unusual presentation should progress to normal per vaginam delivery or calls for a C section.
Intra-uterine Fetal Distress
Signs that all is not well and urgent action might be indicated are recognized decrease or absence of fetal movement, change in fetal heart rate, faster or slower, and staining of amniotic fluid with green meconium
A device to record both fetal movement and uterine contraction, cartiotography, was thought to be able to reduce the risk to the fetus by warning of impending problems, but is reported to have increased the incidence of medical intervention in childbirth without proven benefit.
In the Birth Canal
The most usual position is described as left or right occipito-anterior, in other words the fetus is coming head first, and has his back to the pubis; this is the least space occupying position. “Face to pubis” is undesirable but generally accepted; “breech,” coming bottom first was accepted until recently, but may to some obstetricians be an indication for a Caesarean section. And then there all the thoroughly undesirable presentations of a leading arm or a leading leg or lying transversely.
Another problem in the canal is with the umbilical cord which may be prolapsed, meaning it is coming ahead of the fetus, resulting in compression of the oxygen supply to the fetus as the cord is compressed by the head against the vaginal wall, or may be wrapped around the fetus’ neck so the further down the canal the fetus goes, the tighter becomes the cord.
Within the canal the process of birth may not progress because of uterine inertia or may not progress because of obstruction among the commonest cause now is Shoulder Dystocia, where the leading shoulder jams under the pubis and blocks progress.
Lack of Oxygen (perinatal asphyxia)
The failure of an adequate oxygen supply may be indicated by the fetal distress in utero, when the placenta is probably inadequate, or may occur due to compression of the umbilical cord during progress down the birth canal. Prolonged labour may result in fetal death.
The APGAR immediately after birth assesses the evidence of brain injury from lack of oxygen, but the long term effect, cerebral palsy, remains to be shown in the course of time.
Passive Trauma to the Head in the Birth Canal
The part of the scalp that leads down the canal (presenting part) is likely to be swollen (caput succedaneum), and this resolves in a few days; a prolonged delivery is usually marked by this, whereas a Caesarean section is free of it. Compression of the head may cause some bleeding beneath the skull periosteum (cephalhematoma) which is rarely of consequence. Fractures may occur without interference by attending sta