Health, Wellness, & Self Care,  Little Brother,  Pregnancy & Birth

Optimal fetal positioning: what does science have to say?

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This post is part of a blog series, 31 Days of Preparing for VBAC: my story of purposeful pregnancy, beautiful trial of labor after cesarean, and the healing repeat cesarean birth of my second child. To view all of the posts in this series, check out the landing page. This post has been altered from it’s original posting, after I learned more about optimal fetal positioning after my son’s birth. 

Optimal fetal positioning is a hot buzzword in the natural birthing world, especially when it comes to VBAC. So what is it all about, and why does it matter? More importantly, what does the scientific research say?

My Story

I remember lying there on the operating table when they came back and told me my first baby weighed 9 pounds 13 ounces. There was a relief that swept over me…a justification…a reason I was lying there being sewn up after being unable to push him out. 9 pounds and 13 ounces of a reason.

Yet as the postpartum days turned into months, doubts persisted. Questions, like, “Why did my body grow a baby so big I couldn’t birth it?”

Ezra was approximately six months old when I stumbled upon several websites in the natural birth online community that I thought gave me the beginnings of an answer – optimal fetal positioning.

Women who have been told that their pelvis is “too small”, their babies “too big”, or that their cervix “just doesn’t dilate well” may well have had a problem with baby malposition instead. The popular mentality most doctors have been trained into is that labor problems must lie with the mother, rather than a problem that has gone unrecognized by the provider. So they often reinforce the myth of the ‘too small’ pelvis or the ‘huge’ baby that can’t fit through. Only rarely is this true, however.

A good analogy is a key (the baby) and a lock (the mother’s pelvis). If the key is aligned properly, it slides right into the lock, turns easily, the door opens, and the person moves through. However, if the key is upside down (posterior), sideways (occiput transverse), or even slightly angled to the side (asynclitic), the key has a hard time getting into the lock, let alone getting the person through the door. (Plus Sized Pregnancy)

After reading this, I emailed my midwife and asked her if she remembered what position Ezra was in at the time of birth.

It turns out, he was obliqueright occiput posterior. In other words…WONKY!

It all made sense. Optimal fetal positioning!! I believed I had found the “holy grail” of an answer as to why I had needed a cesarean and how to prevent another one.

So when I got pregnant with Little Brother, one of my biggest priorities was keeping that baby properly positioned in the left anterior position (LOA) – which I had heard on websites, blogs, and podcasts was the optimal fetal position for a baby to be in at the beginning of labor. Unfortunately, this common natural birth advice is not backed by scientific studies, and I was ill-informed:

Association between fetal position at onset of labor and mode of delivery: a prospective cohort study.
Ahmad A1, Webb SS, Early B, Sitch A, Khan K, Macarthur C.
There is no evidence of an association between the fetal LOA position at onset of labor and SVD. This finding challenges the conventional theory that LOA is the optimum fetal position at onset of labor, and suggests that antenatal practices encouraging adoption of the LOA position through maternal posturing are unnecessary.
Full synopsis here:

I started sleeping on my left side immediately. As an adamant back-sleeper, this was difficult for me. Even with a Snoogle, an extra pillow behind my back, and a toddler bed rail installed on the bed to keep all the pillows in place, I STILL ended up on my back multiple times a night (much to my dismay)!

I started yoga in the first trimester and swam and walked every chance I could. I sat on my birth ball often and avoided reclining. I changed my seat in the car to keep my hips tipped as forward as possible. I started bi-monthly trips to my Webster-certified chiropractor. I did exercises such as pelvic tilts and forward leaning inversion almost daily. I tried to visualize baby in a good position, descending through my pelvis, especially when I was walking. I was pretty obsessed with Spinning Babies and Miles Circuit.

I brought up fetal positioning to every single nurse midwife I saw and let them know everything I was doing to prevent malposition. They all told me to relax and assured me that fetal positioning in labor is far more important than fetal positioning in pregnancy – that even malpositioned babies can turn in labor, and that well-positioned babies can malposition during labor.

These studies tell me that my midwives were correct:

Gardberg M1, Laakkonen E, Sälevaara M. Intrapartum sonography and persistent occiput posterior position: a study of 408 deliveries.
In most cases, persistent occiput posterior position develops through a malrotation and only in a little more than one-third of cases through absence of rotation from an initially occipitoposterior position. Higher maternal BMI correlates with higher fetal weight, increased operative deliveries, lower Apgar scores at 1 minute, and posterior placental locations. Intrapartum sonography proved to be useful in investigating the development of the persistent occipitoposterior position.
Full synopsis here: 
Impact on Delivery Outcome of Ultrasonographic Fetal Head Position Prior to Induction of Labor
RESULTS: Ninety-seven (36%) of 270 women with full outcome data had an OP position on ultrasonography before induction of labor. Of these 97 women, eight (8%) were OP at delivery. Sixty-eight percent of the 25 OP positions at delivery occurred due to a mal-rotation from a non-OP position during labor. Logistic regression showed that OP position before induction of labor was not an independent predictor of cesarean delivery (odds ratio 1.75, 95% confidence interval 0.97–3.15, P=.06).
Two thirds of OP positions at delivery after induction of labor occur due to a mal-rotation in labor from a non-OP position. Ultrasonography is an easy method of assessing fetal head position before induction of labor. In clinical practice, its usefulness is limited by the fact that, contrary to conventional teaching, OP position before induction of labor does not appear to be associated with an increased risk of cesarean delivery.

Full synopsis here: Impact on Delivery Outcome of Ultrasonographic Fetal Head Position Prior to Induction of Labor

But, I didn’t believe them, because I thought that people on the Internet knew better. I was convinced that optimal fetal positioning was probably the most important thing I could focus on during my pregnancy.

In short, I obsessed and worried about it…pretty much all the time. It was a very significant stressor for me, and a big source of discouragement when I felt like I was “failing” at it, during my entire pregnancy.

Little Brother seemed to favor my right side throughout most of the second trimester, but after getting my psoas muscle regularly adjusted by my chiropractor, things evened out and he remained positioned well throughout the remainder of the pregnancy. At my last few checkups, the midwives confirmed that he was LOA (left occiput anterior) – what I thought the best position possible for baby to be in at the beginning of labor.

To my knowledge, he remained positioned well throughout my labor and never turned posterior.

I still went postdates. I still had weeks of prodromal labor. And unfortunately, the size of his body and the hardness of his head still kept him from descending. Optimal fetal positioning didn’t keep me from having another cesarean. My body DID grow a baby that I was unable to birth.

Optimal fetal positioning for pregnancy and birth: myths vs. science. Is there any validity to optimal fetal positioning methods such as Spinning Babies, Miles Circuit, rocking on a birth ball, or prenatal yoga to prevent a malpositioned baby?

What the scientific research says about optimal fetal positioning in pregnancy and labor:

Now that I’m postpartum, I’ve taken a closer look at peer-reviewed research on optimal fetal positioning, both in pregnancy and labor, and here is what I have found:

A posterior baby at the time of delivery will be more painful (resulting in higher rates of epidural use with posterior babies), can result in longer labor, can result in anal sphincter injury, and will more likely need an operative delivery (cesarean, forceps, or vacuum). {See studies here: Persistent fetal occiput posterior position: obstetric outcomes and Influence of persistent occiput posterior position on delivery outcome.}

As to why there is a rise in persistent posterior babies and operative outcomes, I found this study, Occipitoposterior Position: Associated Factors and Obstetric Outcome in Nulliparas, to be helpful and insightful. If I understand it correctly, the rise in maternal age may be a factor, as well as better nutrition in moms causing higher birth weights – possibly making it harder for babies to rotate in labor. This study suggests that an anterior placenta can be a factor. A reduced pelvic outlet can also be a factor.

Is there any validity to optimal fetal positioning methods such as Spinning Babies, Miles Circuit, rocking on a birth ball, or prenatal yoga to prevent a malpositioned baby? The research says, NO!

Desbriere, Raoul, Julie Blanc, Renaud Le Dû, Jean-Paul Renner, Xavier Carcopino, Anderson Loundou, and Claude D’ercole. “Is Maternal Posturing during Labor Efficient in Preventing Persistent Occiput Posterior Position? A Randomized Controlled Trial.” American Journal of Obstetrics and Gynecology 208.1 (2013): 60.e1-0.e8.
Our study failed to demonstrate any maternal or neonatal benefit to a policy of maternal posturing for the management of OP position during labor.”
Full synopsis here:
Hofmeyr, G.J., and R. Kulier. “Hands and Knees Posture in Late Pregnancy or Labour for Fetal Malposition (Lateral or Posterior).” Birth 32.3 (2005): 235-36. Web.
“Main results: Two trials of hands and knees posture during pregnancy were included. In one trial involving 100 women, four different postures (four groups of 20 women) were combined for the comparison with the control group of 20 women. Lateral or posterior position of the presenting part of the fetus was less likely to persist following 10 minutes in the hands and knees position compared to a sitting position (one trial, 100 women, relative risk (RR) 0.25, 95% confidence interval (CI) 0.17 to 0.37). In a second trial including 2547 women, advice to assume the hands and knees posture for 10 minutes twice daily in the last weeks of pregnancy had no effect on the baby’s position at delivery or any of the other pregnancy outcomes measured. No trials of hands and knees posture during labour were included.
Authors’ conclusions:
Use of hands and knees position for 10 minutes twice daily to correct occipitoposterior position of the fetus in late pregnancy cannot be recommended as an intervention. This is not to suggest that women should not adopt this position if they find it comfortable. The use of this position during labour has not been addressed in this review. In view of the promising short-term effects of the technique and its simplicity, further trials are justified to determine whether encouraging the use of hands and knees posture during rather than before labour, has any effect on substantive outcomes.”

Full synopsis here:
Kariminia, A. “Randomised Controlled Trial of Effect of Hands and Knees Posturing on Incidence of Occiput Posterior Position at Birth.” Bmj 328.7438 (2004): 490.
Hands and knees exercise with pelvic rocking from 37 weeks’ gestation to the onset of labour did not reduce the incidence of persistent occiput posterior position at birth.”

Full synopsis here:
Matsuo, Koji, Koichiro Shimoya, Norichika Ushioda, and Tadashi Kimura. “Maternal Positioning and Fetal Positioning in Utero.” Journal of Obstetrics and Gynaecology Research 33.3 (2007): 279-82
More women prefer the left lateral position during the second half of pregnancy. More fetuses are in the left occiput in utero during the late stage of pregnancy. However, no statistical relationship was observed between maternal and fetal positioning.”

Full synopsis here: Maternal positioning and fetal positioning in utero.

Malposition: can anything be done about it?

  • Operative delivery: malposition is a very GOOD reason to have a cesarean!

Hindsight is 20-20

I wish I could go back. I wish that I had read these studies when I was pregnant with Little Brother. I wish I had listened to my nurse midwives instead of believing strangers on the Internet. I wish I hadn’t wasted my time leaning over a chair thinking it could prevent a malposition. I wish I hadn’t felt guilty for all that lovely time I spent on my couch instead of rotating on my birth ball. I wish I hadn’t worried about optimal fetal positioning.

Mamas? Relax! If a malposition is going to happen, it’s going to happen. Birth is unpredictable. Rest and enjoy your couch, trust your care providers to take care of you, and know that if you need a cesarean to birth a malpositioned baby, it’s okay.


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