Big Baby trial: (too) early induction

The Truth About Growth Scans and Inductions: What You Need to Know

Pregnancy is a special time full of anticipation, but also full of questions and uncertainties. One of the topics that many pregnant women are concerned with is the reliability of growth scans and the need for inductions, especially when there is a suspected large baby. In this blog we dive deep into a recent study that examines these issues: the “Big Baby” trial. This study, published in The Lancet in 2025, provides valuable insights that you as a pregnant woman need to know in order to make well-informed decisions.

At Verloskundigen Lelystad we believe that knowledge is essential for a positive pregnancy and birth experience. If you are looking for a midwife in Lelystad, we are ready to support you with personal and expert care.

What is shoulder dystocia and why is it important?

Shoulder dystocia is a complication during childbirth in which the baby's shoulder blade becomes trapped behind the mother's pubic bone after the baby's head is born. This can lead to serious problems, such as lack of oxygen to the baby, fractures, or nerve damage. The risk is higher in babies who large for gestational age (LGA), or larger than 95% of babies of the same gestational age. Therefore, researchers and midwives are trying to find ways to reduce this risk, for example by growth scans or inductions.

It's a topic that often gets less attention, but is crucial to understand when you're pregnant and making choices about your birth.

The reliability of growth scans after 36 weeks

Growth scans are ultrasound scans that monitor your baby's growth by measuring the circumference of the abdomen, leg length and head. These measurements estimate the expected birth weight. However, after 36 weeks, these scans become less reliable and it is often incorrectly estimated that the baby will be on the large side at birth. After 36 weeks, the baby has often descended and it is therefore not possible to measure the head circumference correctly, which makes the estimate less accurate because the head circumference is part of the total measurement of the baby's estimated weight.

In the “Big Baby” trial, conducted between June 2018 and October 2021, only 40-42% of babies who were estimated as oversized by ultrasound were actually oversized at birth. This high percentage of incorrect measurements shows that growth scans late in pregnancy often overestimate the size of the baby. This can lead to unnecessary concerns or proposals for inductions that are not necessary.

If you have a midwife in Lelystad If you are looking for a growth scan, we can help you interpret the results of a growth scan and discuss what this means for you.

The “Big Baby” Trial Research: What Are the Findings?

The “Big Baby” trial was a large study in the United Kingdom with 2,893 pregnant women. The aim was to investigate whether early induction of labor (between 38^0 and 38^4 weeks) reduces the risk of shoulder dystocia in babies diagnosed as LGA. The study was stopped even earlier because shoulder dystocia was less common than expected.

The main results were:

• In the intention-to-treat analysis, there was no significant difference in shoulder dystocia between the induction group (2.3%) and the standard care group (3.1%).
• In the per-protocol analysis, which strictly looked at women treated according to the protocol, the risk was lower in the induction group (2.3% vs. 3.7%).
• Early induction led to fewer cesarean sections and postpartum hemorrhage, but a longer hospital stay before delivery.
• There were no differences in neonatal outcomes or serious adverse events.

The study concludes that early induction from 38 weeks may be a safe option, but the benefits have not been convincingly proven.

Implications for pregnant women and midwives

This study offers pregnant women an additional option to reduce the risk of shoulder dystocia, but it also highlights the limitations of growth scans. It is important to discuss with your midwife what the best option is for your situation. Some women feel reassured by an early induction, while others prefer to wait for a natural childbirthIn addition, an induction has several risks, which is why a midwife will always advise to aim for a natural birth if the health of the baby and mother allows this.

At Verloskundigen Lelystad we guide you through these choices. We take the time to answer your questions and make sure you feel comfortable with your decisions. Our personal approach makes us a trusted partner. midwife in Lelystad.

When should you consider a growth scan after 36 weeks?

Growth scans after 36 weeks may be useful if there were previous concerns about a possible lag in the growth of the baby, but not when it comes to the suspicion of a larger baby. After 36 weeks, a growth ultrasound is no longer reliable, because the head cannot be measured properly and therefore the total estimated weight is larger. A smaller growth can often be measured, which is why a growth ultrasound is sometimes advised for too small growth.

Some hospitals also offer growth scans after 36 weeks as standard and use the results to subsequently propose inductions. The most frequently mentioned reason for the hospital to suggest an induction is the expectation of a baby that is too large. This can be confusing, especially because the accuracy of these scans after 36 weeks is very limited. Midwifery practices, such as Verloskundigen Lelystad, therefore do not offer this as standard. Offering inductions is more common when a hospital has a partnership of gynaecologists, because their income depends on the number of inductions. If an induction is discussed and you become confused or uncertain, please come to us.

If you are unsure about an offered growth scan or a proposed induction, discuss this with your midwife. We will help you weigh the pros and cons and make a choice that suits you.

How do you interpret the results of a growth scan?

A growth scan gives an estimate of your baby's birth weight, but this estimate is not always accurate, especially after 36 weeks. If the scan suggests that your baby is large, this does not automatically mean that induction is necessary. It is important to put the results into context, taking into account your medical history and personal preferences. For example, if only the baby's belly is a bit larger, this does not mean that the baby is too large as a whole. There are plenty of babies with a larger belly who are born very healthy without complications. Induction for this reason is therefore not necessary. Only if the baby's total weight is too large (95% or more), it may be wise to consider whether induction is necessary.

At Verloskundigen Lelystad we take the time to discuss the results with you. We look at the bigger picture and help you make a well-considered decision.

Shared decision making: The role of midwives Lelystad

Making decisions during your pregnancy can be overwhelming, especially when you are getting mixed advice. At Verloskundigen Lelystad we are here to support you. Whether it is a growth scan, an induction or another choice, we ensure that you are well informed and your wishes are central. Do not let a hospital influence or confuse you into choosing an induction, but make a well-considered decision and make sure you discuss this with your midwife first so that they can help you by giving you honest information.

If midwife in Lelystad we offer personal care and attention. Contact us for a conversation, so that together we can see what is best for you and your baby.

References and additional information

For more information on this topic, you can consult these resources:

• The Lancet: Effect of early induction of labor on shoulder dystocia

This resource provides an in-depth look at the research and findings.

Conclusion

The “Big Baby” trial shows that early induction could prevent shoulder dystocia in a very small number of cases, but this was so rare that the study was even stopped early. In addition, offering growth scans after 36 weeks is not reliable and the measurement of a baby that is too big after 36 weeks is therefore also not reliable. As a pregnant woman, you deserve clear information to make choices that suit you and that are best for you and the baby. At Verloskundigen Lelystad we are ready to guide you and to discuss with you what the best options are for you. Contact us for personal advice and discover why we are the trusted midwife in Lelystad are.

Overview of key findings

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Take good care of yourself and your future little one!

With warm regards,

Midwives Lelystad
Address: Badweg 21, 8223 PA Lelystad
Telephone: 085 40 19 095