Are "big babies" a good reason for induction of labor? A doula's perspective: suspected macrosomia.

If you're suspecting or expecting a "big baby", you might be wondering, "Should I be induced for a big baby?" If you're wondering about getting induced for a big baby, this post is for you, MamaBear!

When I tell people that my babies were 8lb 4oz, 9lb 4oz, and 10lb 4oz I get some shocked looks. The next question is usually, “VAGINALLY?!” This is when I giggle to myself. My 8 pounder was a c-section. My 9 pounder was a VBAC and the OB exclaimed, “He’s bigger than your C-section baby! Woah! You just VBACd a 9 pound baby!!!” The 10 pounder? Born at home, med free, complication free, minimal tearing, no stitches required. Afterrrrr being told by an MFM the only way I could have another VBAC was in a hospital if the baby isn’t “too big”... My guess is he would have thought she was too big. Let’s talk about big babies and what that means for your birth. This is a long post and an extensive topic so it will be broken into a series. Today we’re going to build the foundation. Fetal Macrosomia is defined by ACOG as, “ fetal growth beyond a specific weight, usually 4,000 g (8 lb, 13 oz) or 4,500 g (9 lb, 4 oz), regardless of the fetal gestational age. Results from large cohort studies support the use of 4,500 g as the weight at which a fetus should be considered macrosomic.” So in Jaimie language over 8lb 13oz is pretty big, 9lb 4oz is pretty damn big (and that 10 pounder was super damn big). But what does that mean? Is macrosomia a risk? Some providers say yes.

It is quite often I hear a mom say, “I’m being induced because I have a big baby.” My response? “Okay. Well how do you know?”

“Ultrasounds show the baby is big. They’re already estimating he’s 7 pounds which means my the time he’s born he’ll probably be 9…. And get stuck.”

“Oh? What was the ultrasound for? Do you or baby have a medical condition?”

“No we’re both healthy. He’s just big. And I’ll need a c-section if we wait.” This is when I get a little twitchy. Let’s look at the evidence.

First we should start with understanding monitoring of fetal growth based off of different models of care.

The midwifery model tends to use a “wait and watch” approach, while the medical model tends to use a “proactive” approach to care. Read here to learn more about the different philosophies in midwifery care model versus medical care model. During prenatal visits, by the third trimester, most moms will experience their weight being monitored, their vitals, baby’s heart rate, and then a measurement of “fundal height”. Typically, we consider “normal growth” to be when the fundal height measures in cm approximately equivalent to weeks gestation (ie. at 32 weeks gestation we’d expect to see the fundal height measuring 30-34cm). Measurements that are consistently high or low, and dramatically so, often send a red flag to providers to request additional testing, typically in the form of ultrasound. We will talk about IUGR (intrauterine growth restriction) in another post, but today we’re talking about macrosomia or big babies, so I’m going to try to stay focused! When fundal height measures high, providers will often perform an ultrasound to determine the cause. Sometimes it’s just that pregnancy’s variation of normal. Sometimes it’s excess fluid. Sometimes it’s all baby.

But what should we do when we have an ultrasound suggesting a baby will be on the bigger side? Are growth ultrasounds accurate? Does it indeed require induction? The not so simple answer: it depends. Like everything else in life, there are so many circumstances at play. But in a normal, healthy dyad without conditions such as Gestational Diabetes, prudence would advise digging deeper. So let’s get back to that mom’s scenario… She was told she needs to be induced for a suspected big baby. Let’s use the BRAIN approach to learning more.

B - Benefits of inducing for a big baby

Some providers will suggest that inducing for a big baby will ensure that the baby is not too large at the time of birth and will prevent the risk of shoulder dystocia or arrested labor and therefore prevent a cesarean. But is this true?

R - Risks of inducing for a big baby

First off, when assessing this risk we need to consider if the diagnostics are even accurate. What is the likelihood we choose this intervention and the baby isn’t actually all that big afterall? Some studies suggest ultrasound predictions can be inaccurate up to 2 pounds in either direction. A systematic review of fetal growth measurement methods revealed that the majority of fetal growth prediction models are inaccurate and inconsistent, and even the ones that tend to be more reliable are very subjective based on the skill of the provider. So risk number one would be choosing to induce out of fear of an issue that doesn’t actually exist. Second, I would be remiss if I didn’t refer to the ACOG guidelines on labor induction for macrosomia. I would paraphrase, but they state this so well, I’ll simply quote them... “ In cases of term patients with suspected fetal macrosomia, current evidence does not support early induction of labor. Results from recent reports indicate that induction of labor at least doubles the risk of cesarean delivery without reducing the risk of shoulder dystocia or newborn morbidity, although the results are affected by small sample size and bias caused by the retrospective nature of the reports. Results from one randomized clinical trial reveal similar cesarean delivery rates in the induction group (19.4 percent) compared with the expectant management group (21.6 percent), with five cases of shoulder dystocia in the induction group and six cases in the expectant management group.”

So in reality, choosing the induction could be increasing your actual risk of cesarean or shoulder dystocia which is one of the things you’re trying to avoid.

A - Alternative approaches

The alternative to an induction for size alone would be to “wait and watch” or perform a “prophylactic cesarean”. We can discuss cesareans for big babies at another time as it would be starting a very detailed BRAIN process all over, and I don’t want to get too far off track. So let’s consider the wait and watch option. The risk of this option would be that you could still have a big baby and you could still have a cesarean. You could also have a normal size baby and a cesarean. Or all could go well and be very straightforward… and you could be surprised with a normal sized baby OR a very large baby (hello unexpected 10 pounder….). If you are choosing to attempt a spontaneous vaginal delivery with a suspected large baby, I highly recommend learning how to work with your body instead of against it so you can give your baby the best chance of not getting stuck.

I - Intuition

What does your intuition say? It’s so important to learn to discern intuition from fear and anxiety. Voices repeating the same scare tactics can make it feel in your gut like you know something awful will happen. Ensure your intuition is not being drown out by fear mongers. Do you believe that your body will not grow a baby too big to birth? Do you believe that letting your baby choose his birthdate is best? Do you believe in your heart and with every fiber of your being that you were built for this and it will all work out the way it should? Or do you feel like your intuition is telling you that things will not go well and something is up and you should proceed with the induction?

N - now/never

How soon would the induction have to be done? Is more monitoring an option? Would more monitoring come with any additional risks? What if we don’t do the induction and everything we discussed comes to fruition and my baby is big and does get stuck? Then what? What does that management look like? How can we prevent it and give ourselves the best chance of a complication free vaginal birth of a big baby? In my next post about birthing a big baby, I’m going to tell you how I successfully birthed 2 clinically “big babies” vaginally and how you can too! I will also be doing a chat about VBAC and big baby, along with preventative cesareans for big babies. I also plan to throw in a post on big babies and gestational diabetes and why there may be different considerations.

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Jaimie Zaki is a military wife, mom, former nurse, birth doula, birth photographer, and international board certified lactation consultant (IBCLC). Jaimie is dedicated to helping MamaBears birth and breastfeed with confidence. Jaimie offers a variety of self-paced online courses to help expectant mothers prepare for childbirth and breastfeeding including The Birth Plan Workshop, Birthing With Confidence, and Breastfeeding With Confidence. Additionally Jaimie provides virtual one-to-one support to help women prepare for their births and to help women troubleshoot breastfeeding challenges. If you are interested in working with Jaimie, please schedule your free 30 minute video call now!

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