Whilst it is fairly common for a preterm baby to change positions in the uterus frequently, by the third trimester most babies prefer to move into a “head down” position. This is thought to be because the top part of the uterus is roomier and allows more space for the baby to move it’s legs (and therefore keep it’s mother up all night!)
Turning “head down” for vaginal delivery is advantageous for a couple of reasons. Firstly, coming out head first allows the cervix to open completely to let the largest part of the baby out first so that the rest generally follows easily. Also, the head fits neatly against the cervix during labour, similar to an egg in an egg cup, which prevent the umbilical cord from slipping out first and being compressed.
Only 1 in 25 babies will be in a breech position (“bottom down”) by 36 weeks, and of these, few will turn themselves to a head down position prior to labour commencing.
For this reason, if your baby is breech at term most obstetricians will discuss three options for delivery:
1. External Cephalic Version (ECV), followed by vaginal delivery
2. Elective planned Caesarean Section at 39 weeks
3. Breech vaginal birth
Up until the start of the millennium, breech vaginal birth was quite common. However, a large international trial published in the year 2000 concluded that breech babies born vaginally had significantly worse outcomes than those born via Caesarean Section. Subsequent to this trial, the rate of vaginal delivery of breech births in Australia has dropped from 23 per cent in 1991 to 3.7 per cent in 2005.
Caesarean Section for a breech baby is generally performed around 39 weeks and typically does not rule out attempting a vaginal birth in a subsequent pregnancy.
External Cephalic Version is the procedure a trained obstetrician will do to turn the baby (version) head down (cephalic) by manipulating her from the outside (external). The procedure is best performed between 37-38 weeks and is successful in 50% of women. A medication may be given prior to the procedure to relax the uterine muscle and increase the ease of the procedure and success rate. It is mildly uncomfortable for the mother and is generally low-risk for the baby. About 1 in 200 babies may become stressed during the procedure and require immediate delivery via urgent Caesarean Section.
Alternative methods for trying to turn a baby to a “head down” position include head down positioning of the mother towards the end of pregnancy, and moxibustion administered by a Traditional Chinese Medicine practitioner. There is minimal evidence to suggest these techniques are helpful, however they do not appear harmful to try.
Planned vaginal breech birth may be chosen by informed parents, however, may not be offered by all obstetricians. The Term Breech Trial demonstrated the importance of having an obstetrician experienced with these deliveries to reduce potential risk to these babies.
If you are considering an ECV or a Breech vaginal birth, a detailed ultrasound scan will be performed to exclude conditions of the uterus (fibroids), placenta (low placenta), baby (too small or too big) or umbilical cord that may reduce the success and safety of these approaches.
Whatever your choice, your baby will join approximately 13500 other breech babies born in Australia this year. And although adorable, they’ll be doing things their own way!
Hannah et al. Planned caesarean section versus planned vaginal birth for breech presentation at term: a randomized multicenter trial. Lancet 2000; 356: 1375–83