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“You’re measuring ahead.”

“This baby looks big on scan.”

“Let’s book an induction… just in case.”

“You’ll have a 3rd or 4th degree tear with your baby being big, a c/section will stop you from tearing”

How many of these have you heard?

We have heard all of them.....multiple times.

We feel, as do other birth workers that we will be hearing it more and more soon.

Earlier this month new research came out “The Big Baby Trial”.

We've condensed the 14 page research down for ya. Let's have a suss together.

What was the Big Baby Trial?

It was a big baby (pun intended 🤣...cough *cough) research study done in the UK to find out:
​If a baby is suspected to be big, does getting induced early lower the chance of shoulder dystocia (baby getting stuck during birth)?

They looked at almost 3,000 pregnant women across over 100 hospitals.

Firstly, what and how did they consider a baby "big"?

It was for babies estimated to be over the 90th percentile for weight on a customised GROW chart between 35 and 38 weeks gestation.

So basically:

• They used ultrasounds to estimate fetal weight.
• Then they plugged that into the GROW chart which adjusts for the mother’s height, weight, ethnicity, and how many babies she’s had to decide if baby was large for gestational age (LGA).
• If baby measured above the 90th percentile, they called that a "big baby."

What did they do?

They split women into two groups:

1. Induction group – women were offered induction at 38 weeks
2. Standard care group – waited for labour to start naturally (unless another reason came up)

What did they actually find?

• Shoulder dystocia happened a bit less in the early induction group.​
  BUT… this only showed up when they looked at people who actually gave birth in the exact research time window they wanted (what’s called a per-protocol analysis).
• In the main group (everyone included, all the women in the induction group + all the women in the wait group), the result differences between them wasn’t big enough to be certain.​
  That’s because lots of women in the “wait and see” group ended up being induced early anyway....in fact 25% of that group either got induced, went into labour (but not at the time frame of the research requirements) or had an elective c/section instead.
• Babies in the induction group were born about 6–8 days earlier and weighed about 160–213g less. What Sara Wickham calls the size of a small avo 🥑 ....we have ponderings on this, which we'll go through in next weeks email.
• Most babies in both groups were totally fine.​
  There were no increases in serious problems with early induction (like tears, c-section, or poor baby outcomes).

What are the problems with this study?

They couldn’t finish the trial.​
They planned to recruit 4,000 women, but stopped early because the number of shoulder dystocia cases was lower than expected.

Scans aren’t reliable.​
Ultrasounds to estimate baby’s size are off by up to 15–20% either way. That’s hundreds of grams. So many babies labeled “big” aren’t actually big.

A quarter of women in the “wait” group were excluded.​
That made the results fuzzy, because the groups ended up more similar in findings than planned.

This matters because, when women in the “wait and see” group ended up birthing early it shrunk the difference in timing and the baby size between the groups.

So when the researchers compared everyone as originally assigned (even if they didn’t follow the research plan exactly), the rates of shoulder dystocia were pretty similar:
➡️ 2.3% in the induction group
➡️ 3.1% in the standard care group
➡️ Not statistically significant (aka not certain - aka no clear answers - aka we are none the wiser)

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We have been here before, and what we have seen as midwives is that some people will pick data out of this research like "Shoulder dystocia happened a bit less in the early induction group." but they don't take on any of the grey areas in the research, the limitations and the trial actually not achieving what it set out to look at.....or tell women any part of that from the trial. For a woman to make her own conclusion from it...not someones biased take from it.

We tell you this, because we hear "big baby" ALL👏THE👏TIME, so its a good chance some of you will also hear "big baby" throughout your pregnancy journey. We want you to know they grey areas, the limitations, the full picture of this "big baby trial".

We want to finish on this a direct quote from one of the researchers

“The trial was stopped early on advice of the data monitoring committee because we weren’t going to reach a big enough sample to get a clear answer.”

The results were interesting, but not conclusive.

Terminology in case it's needed.

Shoulder dystocia is when a baby’s head is born, but one or both shoulders get stuck behind the mother’s pelvic bone, making the rest of the body harder to deliver.

It’s rare and usually managed quickly by the birth team, but it can sometimes cause complications for baby or mum.

Shoulder dystocia is rare. Even in this group of “big babies,” it only happened in about 2–3 out of 100 births.

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We’re so glad you’re here.
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Thanks for being part of this space. More to come.

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The Womanhood Space Team ♡

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