Big Babies, Bold Claims: What the Big Baby Trial Really Tells Us.

You’ve probably heard the phrase “You’re measuring a bit big” at some point in your pregnancy—or maybe your friend or sister has. It’s often followed by murmurs of “just to be safe” inductions or suggestions that “big babies” pose a danger. But how much of that is based on evidence, and how much is fear dressed up as medical advice?

Let’s take a closer look at the Big Baby trial—what it was, what it found (and didn’t find), and why it’s so important to keep body autonomy and instinct front and centre in your birth choices.

What was the Big Baby trial?

The Big Baby trial was a UK-based study looking at whether inducing labour at 38–38+4 weeks would reduce the chance of shoulder dystocia in babies thought to be “big.” The researchers defined “big” as an estimated fetal weight above the 90th centile—often referred to as “macrosomia.”

Now let’s just pause there. That word estimated is doing a lot of heavy lifting.

Because even with today’s technology, we’re often wrong about a baby’s size before birth. Scans can be off by up to 15-20%, and many people who were told they were carrying whoppers went on to birth 7lb babies. On the flip side, many “normal-sized” babies are born weighing 10lb+. Our bodies are not spreadsheets.

What did the Big Baby trial find?

The trial’s authors concluded that inducing labour for a suspected big baby slightly reduced the chance of shoulder dystocia—where the baby’s shoulders get stuck during birth. Sounds serious, right?

Here’s the thing: while shoulder dystocia is something care providers need to know how to manage (and they do), most cases resolve quickly and safely, especially in hands that are trained and calm. The trial also didn’t find any significant differences in actual harm to babies or mothers between the induced and non-induced groups.

In other words: inducing labour didn't lead to healthier outcomes—it just slightly reduced the chance of something that’s already rare and usually manageable.

So why does this matter?

Because recommendations based on this trial could lead to thousands of people being encouraged—or pressured—into early induction, based on an estimate of their baby’s size, despite there being no proven benefit to them or their baby.

And this is where we need to pause and take a breath.

Your body is not broken. Your pelvis doesn’t need measuring. Your baby isn't too big for you just because someone typed a number into a scan machine. Your instincts, your intuition, and your understanding of your own body are just as valid—often more so—than the tech and statistics you’re handed.

Let’s talk autonomy

Here’s the truth: you can say no to induction. You can ask questions. You can ask for evidence. You can say, “What are the risks of doing nothing?” You can tune into your instincts and say, “This doesn’t feel right for me.”

That’s not reckless—it’s powerful. It’s informed. It’s what true choice looks like.

At Cornwall Hypnobirthing, I teach tools to help you feel confident making decisions like this—decisions that aren’t made out of fear, but from a place of strength, knowledge, and trust in your own body.

So what’s the takeaway?

If someone mentions the Big Baby trial to you, or tells you that your baby is looking “a bit big,” know this:

• It’s okay to ask questions.

• It’s okay to decline interventions that don’t sit right with you.

• It’s okay to trust your body—because it knows what to do.

Birth isn’t about predictions and panic—it’s about power, choice, and connection. Let’s change the narrative. Let’s give birth back to the birthing person.

And, don't forget if you ever need support navigating conversations like these, I’m here. . Whether it be hypnobirthing courses, antenatal sessions, birth planning sessions and power hours, I’ve got the evidence, the tools, and the passion to help you feel strong and informed every step of the way

Further reading: For a brilliant breakdown of the Big Baby trial by Dr Sara Wickham, visit: https://www.sarawickham.com/articles-2/bigbaby/