Back-to-back baby (occiput posterior position): labour and birth

Most babies settle head-down with their faces towards the mother's back and their chin tucked onto their chest. NHS inform calls this occipito-anterior. Tommy's explains why it is favoured: it lets the baby flex the back and neck easily, so the narrowest part of the head presses on the cervix and passes through the pelvis more easily.

In an occiput posterior (OP) position the baby is still head-down, but facing the mother's tummy so that the baby's back lies along hers. It is often called back-to-back. Your midwife may feel the position by palpating your tummy at an antenatal appointment, or it may be seen on a late-pregnancy scan, as Tommy's describes. It is one of several ways a baby can lie, alongside breech and transverse.

NHS inform says that in this position the baby's head presses against your lower back and causes backache, which can get worse in labour. Tommy's similarly says it may cause back pain in late pregnancy and during labour.

Backache in pregnancy has many causes, and having it does not mean that your baby is back-to-back. Your midwife can check the baby's position if you are unsure.

NHS inform says it can be more difficult for babies to be born in posterior, breech or transverse positions, and that help from the midwife or doctor, a ventouse or forceps birth or a caesarean may be needed. It adds that once you are ready to go into labour the baby needs to turn all the way around to the front, that contractions sometimes help, and that the baby can also turn when you are pushing.

If the baby does not turn, NHS inform says pushing can result in a baby being born in the posterior position, though this is less likely with a first pregnancy. Tommy's lists a baby being back-to-back or breech among the factors that make a deeper perineal tear more likely, and the RCOG lists a baby lying with its back against yours at the end of labour as a factor that makes an assisted vaginal birth less likely to succeed.

• Longer or more uncomfortable labour is possible, with more backache.

• Help from an obstetrician may be needed if the baby does not turn.

• A higher chance of a deeper tear or assisted birth, as Tommy's and the RCOG describe.

• Many babies do turn and are born without intervention.

Tommy's says some midwives and antenatal teachers believe leaning forwards helps a back-to-back baby turn, for example on hands and knees or leaning over a birth ball. It is open about the limits: there is not much to suggest this approach turns the baby, but the positions can make you more comfortable in late pregnancy and labour, so they may be worth trying.

More generally, Tommy's says moving around and changing position in labour may be linked to a shorter labour, less pain and fewer interventions. The RCOG notes that using upright positions or lying on your side once the cervix is fully open can reduce the need for an assisted vaginal birth. Ask your midwife which positions suit you, especially if you have an epidural.

NHS inform says that if the baby does not turn after pushing, an obstetrician can help turn the baby to face the right way and then deliver with forceps. The NHS forceps and vacuum page says some forceps are specifically designed to turn the baby into the right position, for example when the baby faces upwards (occipito-posterior) or to one side. An assisted birth is used in about 1 in 8 births overall, and the NHS says your consent is needed beforehand.

The NHS lists the usual implications: an episiotomy is likely to be needed, a higher chance of a third- or fourth-degree tear (an estimated 3 in 100 women having a vaginal birth, 4 in 100 with ventouse and 8 to 12 in 100 with forceps), a higher risk of blood clots, urinary leakage that is more common after an assisted birth, and possible small marks or cuts on the baby that usually heal quickly. If there are concerns, you may be moved to theatre so a caesarean can be carried out. Whether to choose a caesarean or an instrumental birth is a discussion with your obstetric team based on your situation.

Tommy's says you should still feel your baby moving right up to and during labour, and that if movements slow, stop or change in any way you should contact your midwife or hospital straight away, because an unwell baby may move less. The same applies whatever position your baby is in. Call your maternity unit if your waters break, you have bleeding, or contractions become regular, following your local instructions. Maternity policies differ across England, Scotland, Wales and Northern Ireland.