Can I Deliver a Big Baby?

Can I Deliver a Big Baby?

We get a lot of calls and questions from women, clients and non-clients, about the fear of growing a baby that is too big. They go in at the end of their pregnancy for an ultrasound and are told the baby is measuring large (fetal macrosomia) and they may need to be induced or have a cesarean. It’s a scary idea, and we totally get it! So let’s break it down a bit and help you create conversation with your healthcare providers should this issue come up.

How do they measure my baby?

Ultrasound techs or your doctor will perform your ultrasound to determine your baby’s size. They will manually measure the size of your baby’s head and stomach, and measure the length of the baby’s femur. They enter those numbers into a program, and that calculates your baby’s size. It’s important to know that the margin for error in late term ultrasound is 20%. On a full term baby, that means over or under by a whole pound! 

Can I vaginally deliver a big baby?

Many women are able to vaginally deliver a big baby. Even women who we perceive as “small” have very adequate space in their pelvis to fit a baby. Your doctor or midwife can determine your pelvic space during a vaginal exam in the very beginning of your pregnancy.

ACOG recommendations

In July 2001, American College of Obstetrics and Gynecology published a statement on big babies. The footnotes are:

  • The methods used to diagnose fetal macrosomia is inaccurate. Using ultrasound measurements is no better than that obtained with clinical palpation (Leopold’s maneuvers). Both methods have a margin of error of 20%. This means your baby can measure a full pound bigger or smaller than they actually are.
  • Suspected fetal macrosomia is not an indication for induction of labor, because induction does not improve maternal or fetal outcomes.
  • Vaginal birth is still recommended is your baby is estimated to weigh less than 5,000 g (10 lbs) if you don’t have diabetes. 
  • If your baby is estimated to weigh more than 4,500 g (8.4 lbs), and your labor stalls in the active stage or the baby doesn’t descend, this is an indication for cesarean delivery.
  • An elective cesarean may be suggested if your baby’s suspected weight is more than 5,000 g (over 10 lbs) in pregnant women without diabetes or more than 4,500 g (8.4 lbs) in pregnant women with diabetes.
  • Suspected fetal macrosomia is not a determining factor for VBAC. This means you are still eligible for a trial of labor (TOLAC).

Statistics for big babies


Questions to consider

We know it sounds silly, but one of the biggest questions to consider is how do YOU feel about your baby’s size? Does your baby feel really big to you?  Have you been feeding your body with healthy foods and has your weight gain been on track with your providers suggestions? Talk with your provider about their experience delivering a larger baby vaginally. Do they tend to take a surgical route more often than not? Have they followed ACOG guidelines for your pregnancy up to this point, and taken your feelings and questions seriously?


Final thought: We are powerful and amazing human beings who grow babies. Most of the time, we are able to safely deliver our babies naturally. Only you and your provider knows your body and what is best for you and your baby. So choose a provider you trust, ask lots of questions, and don’t feel guilty for following your provider’s recommendation when things come up. And of course, you can always call your friendly neighborhood doulas. We are ALWAYS here for you.

One Comment

  1. Feedback – not a public comment.
    I just wanted to query the weights in g vs lbs listed as they are incorrect (5000g/5kg is 11 lbs and 4500g/4.5kg is 9lb 15oz). Assuming the weights in grams are the accurate ones for the article.

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