Optimal fetal positioning: what does science have to say?

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 oblique, right 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:

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:

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.

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!

Malposition: can anything be done about it?

• Utilize epidural anesthesia to manage pain from a malpositioned baby. (This study says that the use anethesia should be encouraged when malposition is present.)

• Manual rotation by a skilled care provider could possibly be effective at correcting a malposition at the time of delivery and avoiding a cesarean: Manual rotation to reduce caesarean delivery in persistent occiput posterior or transverse position

• 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.