In the ideal head-down anterior position, your baby fits snugly into the curve of your pelvis. It allows them to move more easily through your pelvis. The back of his head will be pressing more evenly on your cervix, helping it to open and your labour to progress.
Your baby's back is the heaviest part of its body so it will naturally move towards the lowest side of your abdomen. That's why upright, forward-leaning positions may be helpful during the last few weeks of your pregnancy (from 34 weeks if it's your first, or 37 weeks for subsequent pregnancies).
During labour, your baby will curl his back over, and tuck his chin into his chest. Your labour and birth is more likely to progress smoothly if your baby is in this position, because:
The top of your baby's head puts rounded, even pressure on your cervix (the neck of your womb). During contractions, this pressure will help your cervix to widen and your body to produce the hormones you need for labour.
During the pushing stage (third stage), your baby moves through your pelvis at an angle, so that the smallest area of his head comes first. Try putting on a tight polo neck without tucking in your chin and you'll understand how this works.
When your baby gets to the bottom of your pelvis, he turns his head slightly, so that the widest part of his head is in the widest part of your pelvis. The back of his head can then slip underneath your pubic bone. As he is born, his face sweeps across the area between your vagina and your perineum.
All this has many benefits for you and your baby. If your baby is in an anterior position, you're more likely to:
Give birth without needing an induced labour or caesarean-section.
Have a quicker and more straightforward labour and birth.
You may need less pain relief.
So, what is a posterior (back to back) position?
A posterior position is where your baby has his head down, but the back of his head and his back is against your spine. By the time labour starts at least one baby in 10 is in this posterior position.
Most posterior babies are born vaginally. But this position may make labour more difficult for you, particularly if your baby's chin flexes up, rather than tucked in.
If your baby is posterior at the onset of labour:
You may have backache, as your baby's skull is pushing against your spine and the nerves
Your labour may be long and slow, and may include contractions that start and stop.
A lot of posterior babies turn to an anterior position during labour. When your baby gets to the bottom of your pelvis, he'll need to turn almost 180 degrees to get into the best position.
This can take quite a while, or your baby may decide he's not going to turn at all, which means that he will be born with his face looking up at you as he emerges.
Why are some babies posterior?
Your baby may be posterior because of the type and shape of pelvis that you have. Some women have a pelvis that's narrow and oval (anthropoid pelvis) or wide and heart-shaped (an android pelvis), rather than round-shaped.
How you move and sit may also play a part. When you relax on a comfortable armchair watching TV, or work at a computer for hours, your pelvis is tipped backwards. It is thought that this encourages the back of your baby's head and his spine (the heaviest part of him) to swing round to the back due to gravity.
If you do a lot of upright activities, your baby is more likely to go down into your pelvis in an anterior position, because your pelvis is always tilted forwards.
I can hear you asking, how can I help my baby into an anterior position?
Some experts believe that certain positions can help move your baby from a posterior position into an anterior position. This is known as optimal fetal positioning (OFP). Unfortunately, there isn't much evidence that OFP will help your baby to turn, however, many LMCs and other people still feel it's worth a try. Research does show that some positions can help provide relief from the back pain associated with a posterior position in late pregnancy and during labour.
If you're interested in OFP, these are some of the recommended positions:
Adopt a hands-and-knees position for 10 minutes, twice a day.
Tilt your pelvis forward, rather than back, when you're sitting. Ensure your knees are always lower than your hips.
Check that your favourite seat or car seat doesn't make your bottom go down and your knees come up. If it does, sit on a cushion to lift up your bottom.
Move around if your job involves a lot of sitting, and take regular breaks.
Watch TV or your favourite series kneeling and leaning forward over a swiss ball, or sitting on the ball or turn a dining chair around and sit on it backwards with your arms resting on the back.
Trying these positions can also be useful in other ways in preparation for labour. Upright positions and postures may help you feel more comfortable in later pregnancy. Also, getting used to doing them now will make it easier for you to find the same positions when labour starts - more about the benefits of an active, upright labour in another article.
How do I know what position my baby is in?
Ask your LMC to help you work out the position of your baby.
When you feel your baby wriggling, try to visualise which body part is moving. You could even note down where you're feeling the kicks. Little tickles are probably tiny hands, while more definite movements could be a knee, elbow, or foot.
Your baby's head will feel hard and round, while bottoms usually feel a bit softer.
For an anterior baby: You will probably feel kicks under your ribs. Your baby's back will feel hard and rounded on one side of your tummy. Your belly button might poke out.
For a posterior baby: You'll probably feel more kicks on the front of your tummy, your belly-button might dip and the tummy area feel more squishy.
If your baby continues to stay in the posterior position for labour you may want to vary your positions and movements, and use whichever of the following is most comfortable for you as your labour progresses:
You may find that one of the best positions is on all fours. In this position, your baby drops away from your spine, helping to relieve backache.
Try adopting knees-to-chest positions, on your knees with your head, shoulders and upper chest on the floor or mattress and your bottom in the air.
Lean forwards during your contractions by using a swiss ball, beanbag, your partner, or the bed.
Rock your pelvis during contractions to help your baby turn as he passes through the pelvis. A swiss ball is great for pelvic rocking.
Adopt lunge positions, either when standing on one foot, kneeling on one knee, or when you're lying on the bed. The side that is most comfortable to lunge is likely to be the side that gives your baby more room to turn.
Walk or move every now and again. Don't stay sitting in a chair, or on a bed in a leaning-back position, for too long.
Try not to have an epidural too early on in labour if you can, as epidurals may increase the chance of your baby being in a posterior position at birth. Epidurals also increase the likelihood of you having an assisted labour and birth.
At the end of the day, your baby is going to settle in whatever position is more comfortable for him, but we can be mindful and encourage him into an anterior position as much as we can during your last trimester, after all, you want to make it easier for you and your baby if you can, right?!?
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Medical disclaimer: This page is for educational and informational purposes only and may not be construed as medical advice. The information is not intended to replace medical advice offered by physicians.
