A malpresentation or malposition of the fetus is when the fetus is in any abnormal position, other than vertex (head down) with the occiput anterior or posterior.
The following are considered malpresentations or malpositions:
- Unstable lie
- Breech
- Transverse presentation
- Oblique presentation
- Face presentation
- Brow presentation
- Shoulder presentation
- High head at term
- Prolapsed arm
The cause of a malpresentation can often not be clearly identified but it can be associated with the following:
- Preterm pregnancy
- Uterine anomalies
- Pelvic tumors eg fibroids
- Placenta previa
- Grandmultiparty
- Contracted maternal pelvis
- Multiple gestation
- Too much amniotic fluyid (polyhydramnios)
- Short umbilical cord
- Fetal anomalies (e.g. anencephaly, hydro-cephalus)
- Abnormal fetal motor ability
There is an increased risk of neonatal and maternal complications associated with a malpresentation including neonatal and maternal trauma. If delivery is indicated, doing a cesarean delivery can significantly decrease the risk of complications.
Unstable lie
Breech
Transverse lie
Oblique lie
Face presentation
Brow presentation
In most cases of a normal vertex (head down) presentation, the baby's head is flexed with the chin close to the baby's chest. In these cases, the presenting part is the occiput, the posterior part of the baby's head. If the baby's head is more but not completekly extended then the baby's brow presents towards the vagina. A brow presentation is rare, maybe happening in about 1 in 2,000 births, more likely in pwomen with their second or subsequent births.
A baby with a brow presentation can only deliver vaginally if the head flexes or extends.
Shoulder presentation
High head at term
Prolapsed arm