Up to about 30 weeks, babies will be moving around a lot. Then they settle into one of the following positions, described in more detail below: Anterior presentation;
Your baby lies head-down (known as “cephalic”) and his spine is facing away from your spine. The smallest part of his head will push down the birth canal first (the “vertex” position). This position usually results in a straight forward vaginal delivery.
A lateral presentation is the same as an anterior presentation but with the baby’s spine facing to the side. Most babies engage with the head in the lateral position, and as the head descends into the pelvis during labour, it also rotates – a bit like going through the thread of a screw.
Also head downward, but your baby’s spine is against your spine. The baby will need to make a bigger turn coming down, so labour may take longer. Rarely, the baby may get stuck and need some assistance or even a C-section. You can sometimes help your baby rotate into an anterior position by spending time on all fours leaning against a chair or gym ball and making a figure of eight circles with your bottom.
If a baby is lying diagonally across the uterus, the position is called oblique. It’s very unusual for a baby to stay in this position right up until labour. Only one percent of babies will be transverse or oblique.
Many babies lie sideways early in the pregnancy and turn head down for the last trimester. A few will stay sideways, which can present a risk during the birth since the umbilical cord can sometimes come out of the womb before the baby. If this happens (“umbilical cord prolapse”) the baby then needs to be delivered very fast as the baby will no longer be getting oxygen and there is a chance the baby will die if he is not delivered quickly enough. Sometimes it’s possible to turn the baby before the birth – you can discuss this for your particular case with your obstetrician. It’s almost impossible for a transverse baby to come out naturally, so the usual option is an elective caesarean section. Your baby is in a sideways position, usually on the shoulders or back over your cervix. If the shoulder is presenting first, this position is sometimes called the ‘shoulder’ presentation. The risk of a transverse position increase if you go into labour prematurely, if you have placenta praevia (see below) or if you have had many babies.
A breech presentation – when your baby is positioned bottom or feet first – is the most common position other than head-first presentation. This occurs in around three percent of pregnancies. Your obstetrician and midwife will probably arrange an ultrasound for you, before advising on the safest way for your baby to be delivered. It might be a vaginal birth, or it might be a caesarean section, depending on your situation. If you do opt for a vaginal breech birth, it may be a little more complicated than a normal, head-first delivery as soft bottoms may not dilate the cervix and mould to the pelvic outlet the same way as heads! An epidural may be recommended. Forceps may be needed to deliver the baby’s head. In some hospitals, you will be offered the option of turning your baby to bring them head first at around 37 weeks, see below.
Breech presentation is more likely if the labour starts prematurely or if you have fibroids, excessive amniotic fluid, more than one baby, placenta praevia or an abnormally shaped uterus. In the past breech deliveries were a relatively common part of midwife experience. Midwives today have less experience of assisting a vaginal delivery.
It can sometimes be possible for your obstetrician to move your baby into a headfirst birthing position by applying pressure to a particular position on your bump. This is called an external cephalic version (ECV). It is a good option if you want a vaginal delivery, without the additional risks to the baby. It can be a bit uncomfortable but doesn’t usually hurt. It works around 50 percent of the time, and your baby will usually stay in the head-down position after being turned. This option is only offered after 37 weeks (if it’s done earlier there is a chance that you might go into premature labour) and it can only be done if there is enough amniotic fluid around the baby to cushion the turn. There is also a tiny risk of separating the placenta, or complication with the umbilical cord, so the procedure is undertaken in the hospital where you and the baby can be monitored, there is an ultrasound and there’s emergency backup if necessary. If the external cephalic version doesn’t work, your obstetrician will discuss the alternatives with you – almost always involving a hospital birth, and very possibly a planned caesarean section.
You probably know someone who was delivered vaginally even though they were in breech position, or who have tried alternative therapies. Unsurprisingly, many traditional and alternative therapists have tried to turn babies using anything from Chinese medicine (acupuncturists using moxibustion) to yoga.
There have been a number of studies looking to see if these techniques work but the studies are generally too small or lacking in rigour. If you have a breech baby ask your birth team for advice.
The placenta develops wherever the fertilised egg embeds in your uterus. If this happens in the lower part of the uterus, the placenta will develop in a low-lying position. This often happens and the placenta will then gradually migrate up the uterus as the pregnancy progresses and the uterus expands with your growing baby. If the placenta is still lying low later in pregnancy, it’s called ‘placenta praevia’. This occurs to some degree in around 1 in 200 women. Repeated scans will be suggested to monitor its position.
If the placenta is still covering your cervix near your due date, your baby’s exit route through your vagina could be blocked. The placenta may be near the cervix (minor placenta praevia) or completely covering it (major placenta praevia). In most cases, your baby will need to be born by planned caesarean section. Usually, if the placenta is more than 2.5cm away from the cervical opening and there has been no bleeding, women can attempt a vaginal delivery in a hospital (i.e. not at home or in a birth centre).
Sometimes placenta praevia is the reason your baby might be in a breech or traverse position.
How are twins and multiples delivered?
The vast majority of twin and multiple pregnancies have obstetrician-led care and a hospital birth due to the increased levels of complications both in pregnancy and birth – 40 percent of one or both twins need to be cared for in NICU or SCBU after they are born. Twin births are generally planned to be delivered before 38 weeks to reduce the risk of stillbirth. If you would like to give birth in a midwife-led unit or at home you will need to speak to your birth team to discuss what your options are. Around 40 percent of twins are delivered vaginally and 60 percent by caesarean section, so discuss your preferences and how the pregnancy is going with your birth team. For example, the delivery method may depend on whether or not the twins share a placenta or have a one each – 0r which way the first twin is presenting in your tummy – i.e. head first or a different presentation.
In a vaginal delivery, the first baby is born and then your midwife or obstetrician will check the position of the second baby by feeling your tummy and doing a vaginal examination. The team may check the babies’ positions using an ultrasound scan. If the second baby is in a good position for birth, it should be born soon after the first as the cervix is already fully dilated. If your contractions stop after the birth of the first baby, hormones may be added to the drip to restart them.