Impact on the mother.
Increased incidence of cephalopelvic disproportion and increased caesarean section rates; the main risk of vaginal delivery is obstructed shoulder labour, the incidence of which is proportional to fetal weight. Improper management of obstructed shoulder labour can result in severe vaginal injury and perineal laceration or even uterine rupture; overexpansion of the uterus predisposes to weak uterine contractions and prolonged labour, which can easily lead to post-partum haemorrhage. The prolonged compression of the birth canal by the fetal pre-descendent may lead to urinary or faecal fistula.
The impact on the foetus
Large fetuses often require surgical assistance to deliver and can cause intracranial haemorrhage, clavicle fracture, brachial plexus injury and other birth injuries, and even death in severe cases.