02/11/2026
Alright let’s talk about big babies..
we hear sooo often that you had a scan done and your baby is “measuring big” so your provider wants to either induce early or schedule a c section.
Did you know that ultrasounds can be wrong by an entire pound in either direction? Typically with a margin of error around 10-15% meaning an 8 lb estimate could mean the baby is actually between 6.8 and 9.2 lbs, with inaccuracies growing closer to term and often overestimating very large babies or underestimating smaller ones. While useful for trends, ultrasound weight estimates aren’t precise and shouldn’t solely dictate delivery decisions like early induction.
The general risk of having a macrosomia (over 8 lbs 13 oz) baby is around 8-10%.
Most common risk with big babies is shoulder dystocia. Shoulder dystocia occurs in roughly .15-3% of all vaginal deliveries, but the risk increases to around 14-20% for infants weighing more than 10 lbs. The percentage of babies born over 10 lb is very low, typically around 1% in the United States and globally. Some sources describe such births as “rare”.
The top cause of macrosomia babies are women with gestational diabetes. They face a significantly increased risk of having a large baby with some studies showing risks as high as 20-40% or more, compared to 7-13% in non-diabetic pregnancies, depending on blood sugar control; effective management through diet, exercise, and monitoring can reduce this risk to near-normal levels.
If your doctor is scaring you about the possibility of a shoulder dystocia, I would ask them how they resolve it if it were to happen. Their answer is very telling! Remember it is never too late to switch providers if you don’t feel confident in their ability to resolve shoulder dystocia (which can ALSO happen in 6 lb babies too).