Know Your Evidence: Induction for Big Babies

Originally published in July 2020. Updated May 2024.

Here at Gather Birth, one of our driving goals as we provide support in Minneapolis, St. Paul, and the surrounding areas is to ensure every family has enough quality information and evidence to make the best, most informed decisions during pregnancy, labor, and parenthood. Sometimes it can be hard to find a quick guide in one place, so we’re doing the work for you. We’ve compiled the latest information and evidence from multiple sources and put it in one spot!

This blog’s topic: What does it mean if my baby is ‘measuring big’?

Why might induction be offered to me?

Before we break down the evidence, here are some of the common reasons your OB or midwife may cite when suggesting an early induction (before 40 weeks) for a suspected large baby.

• A large baby’s shoulders may get stuck (shoulder dystocia) while being born.

• A big baby may be at more risk for problems immediately after birth.

• A larger baby could mean more perineal tearing.

• A bigger baby may need assistance during delivery using a vacuum or forceps.

• Your big baby may ultimately need to be born by cesarean section.

Now that we know the common reasons for an induction for a suspected big baby, let’s look at what the evidence tells us.

“Bigger babies have a higher risk of shoulder dystocia.”

Larger babies are at a higher risk for shoulder dystocia during birth. About 14.5% of babies weighing greater than 9 pounds 15 oz. at birth experience shoulder dystocia, compared to the 0.65% of babies weighing less than 8 pounds 13 oz..

However, it’s also essential to know that most shoulder dystocia cases can be resolved quickly by your provider and rarely result in permanent injury to babies (1 out of every 175 birth for babies weighing greater than 9 pounds 15 oz.).

It’s helpful to know that shoulder dystocia cases do not only involve big babies; in fact, around half of the cases happen with smaller or average-sized babies.

While a larger baby can slightly increase your shoulder dystocia risk by 7 to 15%, most cases are handled successfully by providers. Having a smaller or average-sized baby also doesn’t eliminate your risk of shoulder dystocia.

Will induction reduce my risk of shoulder dystocia?

Yes, but not by much. Induction before 40 weeks (typically 37-38 weeks in most significant studies) showed a decreased risk of 4 to 7%. The risk for a shoulder fracture was also decreased, but only by 0.4 to 2%.

“A larger baby may have more complications after birth.”

Currently, the evidence tells us that induction for a suspected larger baby does not decrease your baby’s likelihood of a stay in the NICU. The most recent evidence indicates early induction (37-38 weeks) can increase your baby’s risk of needing treatment for jaundice (which can sometimes mean a longer hospital stay).

Your baby’s health immediately after birth does not appear to be affected much, with APGAR scores being relatively the same regardless of whether your labor was induced or started on its own.

Will induction reduce post-birth complications for my baby?

No. Evidence shows no decrease in APGAR scores or NICU stays but does show an increase in risk for jaundice treatment.

“A big baby means more severe perineal tears.”

Though this idea is used as a reason to induce labor with a suspected big baby, the evidence shows us that the opposite is true.

Parents whose labors were induced experienced an increase in severe tears compared to those who waited for labor to begin on its own, regardless of baby size.

Will induction with a suspected big baby reduce perineal tears?

No. The evidence shows it increases your risk for more severe perineal tearing.

“Larger babies mean the use of a vacuum or forceps is more likely.”

Instrumental delivery (vacuum or forceps) can have risks, like increasing chances for perineal tears, blood clots, and incontinence. Induction for a suspected larger baby on the outset may seem like a way to ensure a vaginal birth without these tools.

The latest evidence shows us there is no decrease in the use of or risk of instrumental birth by early induction for a suspected big baby.

Will induction reduce my risk of forceps or vacuum?

No. The evidence shows no decreased risk.

“If a baby is too big, they will have to be born by cesarean.”

This reasoning to encourage early induction for a suspected larger baby is meant to decrease your likelihood of cesarean birth, which has its own risks and potential complications.

The evidence shows that early induction of labor for a suspected big baby does not decrease your risk of cesarean birth.

In fact, numerous studies show the likelihood of a cesarean may increase, with providers more likely to encourage a cesarean during labor to a parent who has a suspected big baby compared to a parent who has an undiagnosed big baby.

Will early induction decrease my risk of cesarean?

No. Evidence shows it has no impact on reduction but can potentially increase your likelihood of cesarean birth.

Other evidence to consider:

As you partner with your birth team to make the best decision for yourself and your family, it’s important to consider all the information.

• Ultrasounds are accurate around 50% of the time, meaning it’s difficult to accurately predict your baby’s size.

• About 50% of suspected large baby predictions are incorrect.

Questions to ask your provider:

• Can I have another ultrasound on a different day with a different ultrasound technician? I’d like to see if they estimate the same size.

• How are you trained to handle shoulder dystocia? Do you have experience with dystocia? What about the other providers on your team?

• Can we wait another week? How much weight could my baby gain in one week?

• What are my other options?

• What does your induction process look like?

As always, we recommend working with your birth support team (OBGYN, midwife, doula, and specialists) to make the best decision for you and your family. An informed decision, no matter what choice you ultimately make, will always be the best one for you.

Interested in booking a Birth Doula Support Package with Gather Birth Cooperative?

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