Birth Terminology Explained: Posterior, Anterior, Transverse & Breech

Today’s “Birth Terminology Explained” reviews a set of terms that fall under the list of possible positions a baby can be in utero, prior to birth. We’ll explain the different positions, but more importantly help you understand why knowing about them matters. 

The terms for today are posterior, anterior, transverse, and breech, along with their variations.

What Is Anterior? 

Official Definition: A baby in “anterior lie” prior to birth is head down with their face facing your back. This position is the most common and believed to be the ideal position for giving birth. A baby in this position for birth means that the smallest dimension of their head leads the way through the birth canal, thus making it a more ideal position for giving birth. Giving birth in other positions does not mean there will be a problem, but it could mean that labor and birth will look different. Positioning is one of the many normal variables in a birth experience. 

Variations: Anterior is also referred to as “occiput (ie, head) anterior” or OA by health care professionals. Baby’s position can be further classified into ROA or LOA, or right occiput anterior or left occiput anterior. ROA is when baby’s back is aligned to the parent’s right side; the baby’s face faces toward the back, between the left hip and spine. LOA is when baby’s back is aligned to the parent’s left side; the baby’s face faces toward the back, between the right hip and spine. LOA has a reputation for being the best position for birth, but a 2013 study of 1,647 women challenges that theory. 

What Is Posterior? 

Official Definition: A posterior baby (“OP” or occiput posterior) before birth is head down with their face facing your front. This position colloquially referred to as “sunny side up.” A baby in this position for birth means that their head will be against your backside/tailbone. A posterior baby, while very common and a normal variation, can cause longer labors, increased back pain, and longer pushing.  

Variations: Like with the anterior position, there are variations with a posterior baby. LOP or left occiput posterior is when baby is facing your front looking toward your right hip with their back is against your left side. ROP or right occiput posterior is facing your front, looking toward your left hip, back against your right side. 

What Is Transverse?

Official Definition: A baby in a transverse lie is positioned horizontally across the abdomen. This position is uncommon prior to giving birth as most babies turn. If baby remains in this position, a cesarean is necessary for birth. 

What Is Breech?

Official Definition: In it’s simplest definition, breech is when a baby is head up, bottom/feet down prior to birth. Babies can sometimes be successfully turned if they don’t turn on their own, and a breech birth can happen safely, depending on the variation of breech and if the birth is attended by a practitioner experienced in breech birth, as well as other health factors for parent and baby. If baby does not turn and breech is not a safe option, a cesarean is necessary. 

Variations: There are three different kinds of breech: complete breech is when baby’s buttocks are pointed down and legs are folded at the knees, feet resting near baby’s butt; frank breech is when the buttocks are pointed down and legs are facing up with feet near baby’s face/head; footling breech is when one or both of baby’s feet are pointed down below their buttocks.

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When you will hear/see these terms used? Terms that describe baby’s position in utero are most often used once in labor. Since baby’s position can impact the course of labor and birth, your doula, nurse, and/or midwife or OB may try to determine your baby’s positioning if you’re experiencing a slow or stalled labor, or intense back pain. You will also hear about positioning when you take a quality childbirth class, like a Lamaze class. Childbirth educators talk about positioning, its impacts on labor, and what can be done to change baby’s position in pregnancy and in labor.  

Why is it important/beneficial? Knowing about the importance of positioning as it relates to labor progress and ease of birth allows you to learn more about the tools available that can encourage optimal positioning for labor. There are things you can do in pregnancy and in labor to encourage babies to move to positions that facilitate an easier labor. A good childbirth class can help with this, as well as studying resources from Spinning Babies, an approach that encourages the use of body-centered techniques to make optimal room for and positioning of babies for birth.