An ECV does not always succeed in turning the baby into a head down position. The likely success of the procedure depends on many factors including:
Type of breech position
Presence of complications
Previous caesarean
First or subsequent baby
Relaxation of the uterus
Being in labour
Engagement of the baby's bottom
Size of the baby
Posterior breech baby
Amount of amniotic fluid
Woman's weight
Experience of the caregiver
Type of breech position. Babies in a
complete breech position are more likely to be able to be turned. Babies in a
frank breech, or
footling breech position can be turned, but the chances of success are less. Attempts would not be made to turn a
stargazer for fear of spinal injury. Read more in
breech positions.
Presence of complications. If the baby has an abnormality, the placenta is low or the woman has a
bicornuate uterus, then an ECV would not be recommended.
Previous caesarean. Not many studies have been done in relation to doing an ECV on women who have had a previous caesarean. However, from those that have been published, it seems that it is possible and just as safe as it is for women who have not had a caesarean with similar chances of success (up to 85%).
First or subsequent baby. The abdominal muscles of a first time mother are usually tighter, due to being stretched for the first time. With subsequent babies the abdominal muscles are more flexible. For this reason turning a breech baby has higher success rates for women having their second or subsequent baby (from 50 to 85%), rather than for women having their first baby (from 25 to 50%).
Relaxation of the uterus. Tocolytic drugs aim to stop the uterus from contracting. The most common medications used being
betamimetics (ritodrine or salbutamol), which are smooth muscle relaxants, often used to stop
premature labour. They can be used for ECVs to relax the uterus and stop Braxton-Hicks contractions, increasing the chances of it being successful.