8.6.1 Causes of shoulder presentation
Causes of shoulder presentation could be maternal or fetal factors.
Maternal factors include:
- Lax abdominal and uterine muscles: most often after several previous pregnancies
- Uterine abnormality
- Contracted (abnormally narrow) pelvis.
Fetal factors include:
- Preterm labour
- Multiple pregnancy
- Placenta previa.
What do ‘placenta previa’ and ‘polyhydramnios’ indicate?
Placenta previa is when the placenta is partly or completely covering the cervical opening. Polyhydramnios is an excess of amniotic fluid. They are both potential causes of malpresentation.