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The “big baby” threat: why induction for a suspected large baby is often unnecessary and unsupported by evidence
It’s something I hear from women far too often:
“My doctor said my baby is measuring big, so they want to induce me before I go into labour naturally.”
Cue the stress.
The panic.
The pressure.
Suddenly, birth becomes something to be managed, controlled, and timed based on an assumption rather than a certainty.
Let’s talk honestly about this.
Can we really tell how big a baby is before birth?
The short answer? No – not accurately.
Ultrasound is a helpful tool, but its ability to estimate foetal weight in the third trimester is notoriously unreliable.
According to research, estimated foetal weight (EFW) using ultrasound has a margin of error of ±10–15%. That means if a scan suggests your baby weighs 4.0kg, the actual birth weight could range from 3.4kg to 4.6kg.
A study published in Acta Obstetricia et Gynecologica Scandinavica concluded that ultrasound often overestimates foetal weight, especially in women with a higher BMI or advanced gestation:
➤ Melamed N, Ben-Haroush A, Meizner I, Mashiach R, Yogev Y. “Accuracy of sonographic weight estimation in extremely large fetuses.” Acta Obstet Gynecol Scand. 2011. https://pubmed.ncbi.nlm.nih.gov/21306361/
Despite this inaccuracy, many women are told their baby is “too big” and that induction is the safest option – without being shown the full picture.
The Cochrane Review (2016) explored the benefits and risks of induction for suspected foetal macrosomia.
The findings?
There’s limited evidence that induction for a suspected big baby reduces serious outcomes like shoulder dystocia, but no clear evidence it improves overall safety for mother or baby. More importantly, the review highlights that routine induction can increase the likelihood of medical interventions and caesarean birth:
➤ Cochrane Review: “Induction of labour for suspected foetal macrosomia.” Boulvain et al., 2016.
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000938.pub2/full
The risk of shoulder dystocia is often raised during these conversations. Yes, this is a serious situation, but it’s not exclusive to big babies, and it’s also rare.
Research shows that most cases of shoulder dystocia occur in babies weighing under 4kg.
One study in the Journal of Perinatal Education notes:
“Macrosomia increases the risk of shoulder dystocia modestly, but shoulder dystocia is unpredictable and can occur in babies of average size.”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1595200/
The fear of shoulder dystocia is often more powerful than the facts.
Dr Sara Wickham released her take on the “Big Baby Trial” in the UK that was released in May 2025, and she unpacks the data, the language, and the real story behind what many are calling “big baby syndrome” particularly when it comes to shoulder dystocia. Her breakdown offers important insights into how risk is often framed and sometimes exaggerated when it comes to larger babies. It is definitely worth a read if you’ve ever been told your baby is “measuring big.”
https://www.sarawickham.com/articles-2/bigbaby/
When induction is offered for a suspected big baby, it’s important to consider the risks of the procedure itself:
A systematic review in the American Journal of Obstetrics and Gynecology found that elective induction before 40 weeks in first-time mothers significantly increased caesarean rates compared to spontaneous labour.
Many women birth 4kg+ babies without complications, especially when:
Our bodies are designed to birth the babies they grow. A larger baby doesn’t equal a more dangerous birth. But fear-based decisions can make birth more difficult than it needs to be.
When a woman is planning a VBAC (vaginal birth after caesarean), the mention of a “big baby” can ramp up the pressure to schedule a repeat caesarean or early induction. Yet the evidence does not support routine intervention based solely on estimated size.
In fact, many women successfully birth larger babies vaginally – even after a previous caesarean. The fear often stems from exaggerated concerns about uterine rupture or shoulder dystocia, but these risks are still low and must be weighed against the risks of repeat caesarean surgery.
It’s important that women planning a VBAC receive accurate information, respectful care, and the opportunity to go into spontaneous labour, rather than being funnelled into unnecessary interventions based on size estimates that, as research shows, can be significantly inaccurate.
If you’re being told your baby is big, and induction is being suggested, ask:
This is where your role is so powerful.
You’re not there to give medical advice, but you are there to help women feel supported and informed. When they’re told, “Your baby is too big,” and induction is being pushed, you can offer calm, evidence-informed space for them to explore their options.
This isn’t about resisting medical advice, it’s about understanding what informed choice truly means.
It’s essential that we talk openly with our clients about scenarios like the “big baby” label, which often comes up in the third trimester. It’s common for women to be told their baby might be big, even without accurate evidence, so as doulas we can gently guide them toward informed decision-making. One helpful way is to gather balanced, evidence-based resources to share, allowing them to explore the topic in more depth. We can also shift the language – reframing “big baby” to something more positive, like “healthy baby,” to reduce fear and anxiety.
Another point worth highlighting is the inconsistency in some of the information women receive. For example, one woman might be told she needs to be induced at 39 weeks because the placenta may start to deteriorate and stop nourishing the baby. Yet another is told that if she goes beyond 39 weeks, her placenta might be providing too many nutrients, causing the baby to grow too large. These contradictory messages simply don’t add up, and it’s important to help our clients recognise when the information doesn’t align logically or evidence-wise, so they feel confident asking questions and making the decisions that are right for them.
You deserve to know that your body is not broken.
A larger baby is not a ticking time bomb.
With the right preparation – physical alignment, emotional support, and space to make decisions, you can walk into birth feeling capable and clear.
If you want to understand how to support your body to make space for your baby and prepare for birth, explore our Maternal Alignment Blueprint approach. We focus on stability, mobility, and pelvic space – so you’re not just waiting for labour but actively preparing for it.
You don’t need to be rushed into birth.
You need information, support, and trust in your body.
First things first – breathe.
Hearing that your baby may be large can feel overwhelming, especially if it comes with pressure to induce. But remember you have time, and you have options. Here’s how you can respond with clarity, not fear:
You are allowed to ask questions.
You are allowed to decline.
You are allowed to wait.
A suspected “big baby” is not an automatic emergency.
Birth is not one-size-fits-all, and neither are the decisions that lead up to it.
Don’t forget to use your BRAIN analogy – Use your BRAIN to ask all the right questions, to get all the information you need to make an informed decision.
What are the BENEFITS?
What are the RISKS?
What are the ALTERNATIVES?
What are my INSTINCTS telling me?
What if I wait and do NOTHING and reassess later?
For guidance that’s grounded, realistic, and based on years of experience supporting women through pregnancy and birth book into one of my Back to Basics Birthing classes.
If you have any questions or would just like more information please don't hesitate to get in touch by clicking the button below and filling out the contact form.
Contact Vicki