BIG Babies! What it means for Mum & Bub.

Having worked with many women as they prepare for childbirth and welcoming a little one into their world, it constantly surprises me at the number who are told they're 'having a big baby' or their 'pelvis seems small for the size of their baby'.

You might be wondering why I find it so interesting (and often very frustrating) to hear that so many parents-to-be are told this. I mean, does it really matter??


Research demonstrates that in babies born with a birth weight of 9 pound or greater, ultrasound was accurate ONLY between 20-30%.

So what does this mean?

It means that often, women are being warned that their baby is measuring big when in fact baby is a perfectly 'normal' size. This can be a problem as it increases the likelihood of intervention such as induction and cesarean which each come with significant risks to both mother and child.

Interestingly, the risks associated with a cesarean birth or other interventions tend to be much more serious than those linked with vaginally birthing a large baby.

What about if your birth professional suspects a big baby after palpating or feeling your bump?

Actually, a practitioners ability to accurately measure baby was equally as poor as ultrasound and even with the 'best' protocol available, research shows a discrepancy of around 15%. That can add more than a whole pound in an eight pound baby. And that's the BEST method we have to assess foetal size.

What's more, is that research has also showed that the women who are informed they are measuring 'big' and are counselled on the risks of having a big baby have much higher risk of intervention. This is SO important as it demonstrates that it's the mothers awareness (and I suspect fear and self doubt) of birthing a potentially big baby that changes outcomes rather than the big baby itself.

Rhea Dempsey's book 'Birth with Confidence' reflects this research. She explains how it is vital to work with your baby and body during labour and birth and have confidence in your ability to birth your baby. And we'd have to say, after seeing this research, we totally agree!

But what if baby IS big? What are the risks?

Injury to mother or baby are the biggest concerns with a big baby.

Things like tearing for the mother, emergency cesarean if baby were to become stuck, nerve injure (called brachial plexus injury) or injury to babies hips are the most common reasons birth professionals push for intervention when baby is suspected to be large.

Each of these are very rare when looking at the research, with one study showing nerve damage in only 1 in 555 babies who weigh between 8 lbs., 13 oz and 9 lbs., 15 oz, (3688 grams). The study also noted the same injury in 1 in 175 babies who weigh 9 lbs., 15 oz. (4150 grams) or greater.

To put that into perspective, there were only a very small 1.6% of Australian babies born larger than 4500 grams in 2013. So the risk of actually having a big baby is very low, with the chance of having a big baby with an injury to mother or child even lower.

MY BABY IS MEASURING BIG! What can I do to help?

Firstly, don't panic! As we've mentioned, there is lots of discrepancy in accuracy of measurement. But here are some things you can do to help.

1. Read Birth With Confidence.

We cannot suggest this book enough. Rhea is so clever in giving women back their wisdom and power in the birth world. It will absolutely help you to prepare for a wonderful birth experience.

2. Get Physical!

Well maybe not physical, but active! There is lots of studies showing benefits of active birth positions, particularly squatting, for making the birth canal bigger by up to 30% and allowing baby to descend more easily in comparison to the 'text book' birthing on your back position.

3. Word up your support people.

If what you're after is less intervention, it's important to have that conversation with your care provider. Be ready to stand up for yourself and set some boundaries about interventions and when you would consider them appropriate if your provider has mentioned a big baby.

4. Choose to not be informed of every single unlikely risk.

This might go against the grain for every one of you educated and empowered women. But like we've mentioned, the research says those who aren't counselled about the risks have far better outcomes.

5. Prepare your body.

It just makes sense that ensuring your pelvis and the supporting ligaments and muscles are functioning well and balanced prior to birth, regardless of how big baby is. Check in with your prenatal trained acupuncturist or Chiropractor.

6. Zen. Zen. Zen.

There is mounting evidence to show that your mindset has an enormous role to play in birth outcomes. Practicing meditation, mindfulness or hypnosis can be a huge help. We personally loveeee the Headspace or the Mind the Bump App.


This research doesn't reflect that which is relevant to women with Gestational Diabetes.

Women in this category may have different risks and outcomes and it is important you discuss your options with a health professional.

Enjoy! - BBB x



Australian Mothers & Babies 2013: In Brief. 15th Dec 2015.

Rouse et al. The effectiveness and costs of elective cesarean delivery for fetal macrosomia diagnosed by ultrasound. JAMA 1996 Nov 13;276(18):1480-6

Weissmann-Brenner et al. Maternal and neonatal outcomes of macrosomic pregnancies. Med Sci Monit. 2012 Sep;18(9):PH77-81.

Sadeh-Mestechkin D et al. Suspected macrosomia? Better not tell. Arch Gynecol Obstet 2008 Sep;278(3):225-30

Chauhan et al. Suspicion and treatment of the macrosomic fetus: a review. American Journal of Obstetrics and Gynecology. 2005 Aug;193(2):332-46.

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