Does baby’s position in labor matter? Part 2 of 2

“When you hear hoofbeats behind you, don’t expect to see a zebra.”

Dr. Theodore Woodward (1940)

When doulas hear the word “posterior” or OP during labor, often they immediately think “problem that needs fixed”. It is essential for doulas and laboring women alike to understand that an OP baby in and of itself is not indicative of a problem. In fact, a majority of the time an OP baby is part of the normal labor process and the vast majority of the time, babies either rotate just fine on their own, or the OP position is what is needed for baby to fit through the pelvis.

 

Many doulas and pregnant women believe a baby who is OP is malpositioned. They also believe that the OA position, or facing the pregnant person’s back, is the ideal position for labor and birth.

 

Yes and no.

First, it is important to understand the idea of dextro-rotation. Put simply – clockwise rotation.

 

If we look back into the obstetrical literature even as early as the 1930’s we see there that they noted that babies rotated into the most open parts of the pelvis, which is clockwise.

Additionally, there are three types of muscle fibers in the uterus. On the outer layer, the muscle fibers run from top to bottom. These layers draw up as the pregnant uterus contracts in response to labor and are responsible for dilation. The middle layer of uterine fibers are made up of fibers in a figure eight pattern and the innermost layer of muscle fibers are circular fibers the fibers of the two inner layers work together to help the baby rotate through the cardinal movements during labor and help baby align with the pelvis.

 

Both the powers and the passage encourage clockwise rotation of the baby through the pelvis.
Second, it is important to understand pelvic shapes.  Click here for a general overview on pelvic shapes.

With the gynecoid pelvis, the baby enters the pelvis in an ROT, ROP, LOP, or LOT position. The anthropoid pelvis requires the baby to be direct OP or direct OA. An android pelvis baby enters at ROP or LOP. The platypelloid baby will be ROT or LOT as it begins to navigate the pelvis.

 

Fetal occiput positions at onset of labor:

ROA: 3.8%

ROT: 19.1%

ROP: 11.9%

OP: 4.4%

LOP: 13.4%

LOT: 27.4%

LOA: 12.4%

OA: 7.6%

 

If we start with the idea of dextro-rotation and add in how different pelvic types require baby to enter the pelvis, it is easy to see that the majority of babies will be OP at some point in labor.

 

In other words: it is normal for most babies to be OP at some point in labor. An OP baby in and of itself is not cause for alarm. Research also shows no association between the position of baby at the start of labor and mode of delivery.

 

Additionally, only about 12% of babies will be persistent OP throughout labor and birth, especially for those with an anthropoid pelvis type.

 

This is not to say that an OP labor can’t be more painful or have more complications. It can. When this happens, the question becomes what do we do about it? Do we focus on helping the laboring person to cope or do we attempt to rotate the baby with maternal positioning?

 

As doulas, we help the laboring person to cope as there is no evidence to support the use of maternal positioning to facilitate rotation. Please understand we are not saying there hasn’t been research on this. There has been. Researchers have looked at hands and knees, knee-chest, and a variety of side lying postures such as Miles Circuit. The results are the same: “there is no evidence to support maternal positioning to encourage rotation of the occiput in the active phase” of labor.

 

To be clear: hands and knees can help with comfort, and should be used as such. But the idea that it will help baby turn is false. Especially if you apply the idea of dextro-rotation.

Finally, through our combined 28 years as doulas, one idea we have often heard is that persistent OP babies are a major cause of unnecessary cesareans. We don’t disagree that persistent OP babies have higher cesarean birth rates. Research tells us that a persistent OP presentation increases the risk of cesarean by 4 to 10 times that of a non-posterior baby, “with absolute rates as high as 65%.” The operative vaginal delivery rate is 6-11 times higher than what it would be for non-posterior babies.

 

Clearly the potential for cesarean is higher. But does it hold that it’s often unnecessary? This is an idea which we find contributes to the belief some women hold that their body is somehow broken.

 

Cesarean birth due to persistent occiput posterior presentation is often necessary and we need to recognize the realities of not having access to surgical birth.

 

Before we dive into this last section, we want our intent to be clear. The research shows us that most babies will be OP at some point in labor, and the vast majority of the time it does not cause issues with the labor. When it does, we need to focus on the comfort of the laboring person rather than rotation, as there is no evidence to suggest maternal posturing will fix baby’s position, and most babies will rotate just fine on their own.

 

There are also some pelvis types that require baby to be OP when they enter the pelvis. We often do not see complications with labor and birth in these cases. Also, only 5%-12% of babies will be persistent OP in labor and birth. Of those babies who are persistent OP, there is an increased risk of complications. It is important to understand this fact, not because we need to “do something” about OP babies, but because we often cannot do anything so in these cases access to cesarean birth is essential. The need for these cesareans is not caused by a broken body or a woman’s failure to push out her baby. On the contrary, the need for cesarean birth in these cases is to protect the birthing person’s long term health and sometimes even their life and their baby’s life.

 

In the article “Persistent Occiput Posterior” from a 2015 publication of Obstetrics & Gynecology, author Dr. William Barth explains why we see increased maternal morbidity with persistent OP babies. This is what we know about the fetal head in labor and delivery:

• OA presentation (the green line) gives an average diameter of 9.5 cm passing through the pelvic outlet and over the perineum.
• OP presentation (yellow line) gives a diameter of approximately 11.5 cm.
• Brow presentation (red line) gives a diameter of approximately 13.5 cm.

 

Because the head diameter is much larger in typical OP and brow presentations, it is no surprise that these presentations have higher rates of third and fourth-degree perineal tears and 33% increased risk of third and fourth-degree extensions with operative vaginal delivery with an OP baby when compared to an OA baby. These injuries have the potential to cause life-long issues for the birthing person.

 

Some argue we just need to give the birthing person more time, as they believe a longer and harder pushing stage is a variation of normal with an OP baby, and it is the rushing that causes the above complications. But when we look at countries who do not have access to operating rooms and instrumental delivery, we see a very different picture.

 

To be clear, we understand the information that follows is not completely transferrable to the US as it is based on populations with other risk factors. However, we believe this data gives an important perspective that is often not considered when discussing risks of cesarean in the case of persistent OP presentation.

 

A publication from the WHO in 2000 tells us that obstructed labor occurs in 3-6% of all labors worldwide. A 2010 study from the Ethiopian Journal of Health Sciences breaks down the numbers from one hospital. The vast majority of obstructed labors were due to cephalopelvic disproportion (67.6%). These cases of CPD are often caused by pelvic abnormalities, but the authors note some of the CPD cases were due to malpresentation.

 

What’s interesting to us is that 27.9% of obstructed labors were recorded as being caused by a malpositioned baby. The most common complication of obstructed labor was uterine rupture (45.1%) and then sepsis (39.3%). A combination of complications occurred 15.1% of the time. None of the women had a scarred uterus. Only 45.8% of the babies were born alive, and all of them had low 1-minute APGAR scores, 75.6% had a “normal” 5-minute APGAR score. The maternal mortality rate for obstructed labor in the study hospital is 91/1000.

 

Again, this is about perspective.

 

Some babies need to be born via cesarean birth, and it’s not because women’s bodies are broken. It’s the job of the cervix to dilate, and baby’s job is to rotate.

 

At the end of the day, we need to recognize that baby’s position is often something we have no control over, much like other aspects of labor and birth. We need to be honest with ourselves and our clients about this fact, as the implication of control has the potential for the birthing person to feel guilt over the birth of their baby if it did not proceed as desired. Furthermore, we are very privileged to have quick access to cesarean birth in cases of OP presentation causing labor dystocia, and we need to honor this mode of birth in the same way we honor vaginal birth.

Part 1 of Does baby’s position matter in labor? click the link to visit Columbus Birth & Parenting’s blog!

 

References

 

Ahmad, A., et al. Association between fetal position at onset of labor and mode of delivery: a prospective cohort study. Ultrasound Obsetet Gynecol. 2014; 43: 176-182.

 

Barth, W.H. Persistent Occiput Posterior. Obstet Gynecol 2015;125:695–709.

 

Desbriere R, Blanc J, Le Dû R, et al. Is maternal posturing during labor efficient in preventing persistent occiput posterior position? A randomized controlled trial. Am J Obstet Gynecol 2013;208:60.e1-8.

 

Fantu S, Segni H, Alemseged F. Incidence, Causes and Outcome of Obstructed Labor in Jimma University Specialized Hospital. Ethiopian Journal of Health Sciences. 2010;20(3):145-151.

 

Hart, J., Walker, A. Management of Occiput Posterior Position. Journal of Midwifery & Women’s Health. 2007;52:508-513

 

Kariminia A, Chamberlain MF, Keogh J, Shea A. Randomized controlled trial of effect of hands and knees posturing on incidence of occiput posterior position at birth. BMJ 2004;328:490.

 

Lee, N., et al. ‘Facing the wrong way’: Exploring the Occipito Posterior position/back pain discourse from women’s and midwives perspectives. Midwifery (2015), http://dx.doi.org/10.1016/j.midw.2015.06.003.

 

Lieberman, E., et al. Changes in fetal position during labor and their association with epidural analgesia. Obstet Gynecol. 2005 May;105(5 Pt 1):974-82.

 

Ridley, R. Diagnosis and Intervention for Occiput Posterior Malposition. JOGNN. 2007;36:135-143.

 

Simkin, P. The Fetal Occiput Posterior Position: State of the Science and a New Perspective. Birth. 2010;37:61-71.

 

Simkin, Penny. ‘The Occiput Posterior Fetus: How Little We Know’. 2005. Presentation.

Stremler, R. et al. Hands-and-Knees Positioning During Labor with Epidural Analgesia. JOGNN. 2009;38:391-398.

 

Stremler, R. et al. Randomized Controlled Trial of Hands-and-Knees Positioning for Occipitoposterior Position in Labor. Birth. 2005;32:243-251.