Which Way’s Up?

Which way’s up?

When a midwife or doctor is examining your pregnant belly, you may hear them describe your baby’s position. The position your baby is in is meaningful because it can affect your labour, and possibly whether your baby can be born safely vaginally.

Here are some explanations of the terms you might hear and how it can affect your birth:

Lie

• The relation of the long axis (head to bottom) of the baby to that of its mother.
• Lie is either longitudinal (the pink, green or blue baby in the picture below) or transverse (the other baby).
• A longitudinal lie means that baby is either head down or bottom down.
• Occasionally the baby and the maternal axis may cross at 45 degrees forming an oblique lie. This lie is unstable and must become longitudinal or transverse for a baby to be born.
• Babies cannot be born vaginally in the transverse or oblique. Oblique babies may adjust themselves with a little help. Transverse babies may need help (in the form of an External Cephalic Version) to reposition themselves or be born by caesarean section.

Presenting part

• The portion of the baby that is either within or closest to the birth canal.
• When the lie is longitudinal, the presentation will be either cephalic (head down – pink or blue baby) or breech (green baby).
• In a transverse lie (the other baby) the presenting part will most likely be the baby’s shoulder.
• A compound presentation is when more than one part of the baby’s body is in the birth canal. Most of the time it is a hand up beside baby’s head.

Cephalic presentations are classified according to the baby’s attitude (how tucked in the baby’s head is to its chest). When the chin is tucked in close to the chest (flexed) it is called a vertex presentation. This position is the ideal presentation for baby to be born in. However, not all babies get themselves in this position. If the baby does not have its head tucked in, we call it deflexed.

Sometimes baby flexes its head during labour. Sometimes it does not. If the baby’s head is midway between full flexion and full extension, it is called a brow presentation. When baby’s head is thrust back (fully extended), and the back of the baby’s head is touching its back, the face is in the birth canal. We call this a face presentation.

What about breech?

Breech presentations are classified according to the position of baby’s legs – frank breech, complete breech and incomplete breech. A baby in frank breech position is flexed at the hips and extended at the knees. The baby’s feet are up by its face. A complete breech has both hips and knees flexed. An incomplete breech is when one or both hips are NOT flexed, and one or both feet lie below the baby’s bottom so that it is a foot or knee presenting in the birth canal. If it is a foot presenting it is known as a footling breech.

Babies may be born vaginally in breech presentation under some circumstances. They may also be able to be turned to a cephalic presentation by External Cephalic Version (ECV). If either of these options is not safe for you, then baby can be born by caesarean section.

Position

Refers to the relationship of the baby’s presenting part (head or tail) to the mother’s right or left side. You may hear your midwife referring to your baby as OA or OP.

• OA (Occiput – back of baby’s head, Anterior – to the front) is the ideal birth position for most babies (pink baby below). The occiput, and hence the baby’s back, might be on the mothers’ right- or left-hand side and rotated toward the mothers’ front (ROA, LOA or direct OA).
• OP (Occiput – back of baby’s head, Posterior – to the back) babies are also known as spine to spine. We call it this as the baby’s back is rotated toward the mothers back (ROP, LOP or direct OP) (blue baby below).

OP position

In the OP position, your baby’s head presses against the nerves in your tailbone. This position can cause back pain which can be worse in labour. There are some things you can do before your baby is born, which may help your baby into a better position. From about 36 weeks you can try leaning forward whenever you can.

These movements may help your baby to turn, so that baby’s back is toward your front before its head engages in your pelvis in preparation for the birth. If the baby doesn’t cooperate, don’t worry too much. You can also remain mobile during your labour which will encourage your baby to turn. If the baby doesn’t want to turn, he or she is still able to be born, just face up instead of face down.

Asynclitic

Sometimes baby’s head is tilted off to the side. When this happens, it is called asynclitic. It is more difficult for the baby to be born when their head tilts (if you have ever tried to get your head through the neck of a jumper sideways, you will understand). The best way to help your baby move his or her head is to stay mobile. You can do this with the help of your midwife even if you have an epidural. Most babies will be able to straighten their head out and be born without further assistance.

To watch more videos on helping position your baby please see the Spinning Babies website.

Dr Janelle McAlpine (PhD), Clinical Midwife
Image by szefei, used under license from Shutterstock.com

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