Delivering a large baby vaginally is a common concern among parents. For parents who want to avoid a repeat C-section, it can be especially painful to hear that the baby is too big for a vaginal delivery.
As doulas, we hear time and time again how women have been diagnosed with a small pelvis or told their bodies make babies too big for a vaginal birth.
I have had clients who were told their baby will be larger than 9 pounds, only to deliver a 7-8 pound baby. I have also seen parents deliver 10+ pound babies vaginally, both at home and in the hospital.
Studies on big babies show that when a provider thinks you have a larger than average baby, your chances of having a Cesarean increase drastically.
The good news is that there are many things you can do to improve your chances of a vaginal birth if you do happen to be carrying a baby on the larger side.
First, let’s discuss the size most providers consider to be large for a baby and how to know if your baby is big. We will also talk about the ideal baby weight for vaginal delivery and all the ways you can prepare to push that big baby out and avoid a C-section.
Originally published in April 2019, this article was updated and republished on February 8, 2021.
What Is Considered A Big Baby?
The medical term for big babies is macrosomia, literally meaning “big body.” However, you will find that many different definitions are used to define a big baby, even from provider to provider.
Here is what ACOG says about big babies and macrosomia:
The term fetal macrosomia implies fetal growth beyond a specific weight, usually 4,000 g (8 lb, 13 oz) or 4,500 g (9 lb, 4 oz), regardless of the fetal gestational age. Results from large cohort studies support the use of 4,500 g [9 ln 4 oz] as the weight at which a fetus should be considered macrosomic.ACOG Practice Bulletin 216
A baby will also be considered big if they measure above the 90th percentile for their gestational age, also called LGA (Large for Gestational Age), regardless of their actual weight.
Less than 10% of babies worldwide are born weighing more than 8 lbs 13 oz (including one of my VBAC babies, thank you, baby #4). However, one in three women will be told they have a big baby near the end of their pregnancy. Half of those will end up with a C-section because of the bias that comes with a suspected big baby.
The best thing you can do to prepare yourself for any unnecessary interventions is to know the facts about big babies, how to help a larger baby out (see what I did there?), and know the limitations of size estimates before birth.
What Determines Baby Birth Weight?
If your provider suspects you will be delivering a large baby, they may recommend a third-trimester ultrasound to try and estimate your baby’s size.
Third-trimester ultrasounds are notorious for being off by 15%, or 1-2 pounds, and usually measure babies bigger than they are. I have seen it repeatedly where a parent or provider is sure the baby will be over 9 pounds, only to see an average-sized baby at birth.
The hardest thing about big babies is there is no accurate way to determine if you are going to have a big baby or not. The only accurate method for measuring a baby’s size is to weigh it after it is born.
However, some factors influence whether you will have a larger than average newborn.
Good old fashioned genetics play a role in the size of your baby. In general, your babies are likely to be in a similar weight range as you and your partner. In other words, it’s highly unlikely that you’ll give birth to a six-pound mini-you if you were nine pounds at birth.
One study showed that if you have previously given birth to a baby over 9 pounds, you are 25% more likely to give birth to a baby over nine pounds in the future.
Other hereditary factors that increase your chances of birthing a larger baby are Caucasian ethnicity, higher pre-pregnancy BMI, and having a male baby — dang those boy babies.
Pregnancy Weight Gain
Your provider has probably recommended that you maintain a healthy weight gain during pregnancy. Hopefully, they have even discussed good pregnancy nutrition with you. There is a correlation between weight gain during pregnancy and the baby’s size but, the reasons for that correlation are not fully understood.
However, one study in the JAMA journal sheds some light on the factors that link the two. The study found strong evidence that mom’s weight, blood sugar levels, and blood pressure directly influence the infant’s weight.
But don’t worry, having a plus-size pregnancy doesn’t automatically mean you will have a large baby. Pregnancy is not a time to drastically change your diet, but making healthier food choices and getting a moderate amount of exercise will help keep your baby’s weight right on track.
Type I, Type II, and gestational diabetes impact the mother’s blood glucose levels, and if left uncontrolled, will cause a baby to be heavier at birth.
The interesting thing is that having gestational diabetes puts you at higher risk of having gestational hypertension (high blood pressure) and preeclampsia, which decrease the baby’s size.
Babies born after 40 weeks also tend to be slightly bigger; this does not mean that you should avoid going beyond 40 weeks. It’s good that the baby is growing, and going into spontaneous labor is still associated with better birth outcomes overall.
Ideal Baby Weight For Normal Delivery
According to ACOG, the average size of babies born in the United States is 7 lbs 14 oz. However, the ideal weight for you might be bigger or smaller.
How your pelvis relaxes and moves and how your baby’s head flexes and molds all come into play when it comes time to give birth. I have seen 6 lb babies born by Cesarean because they wouldn’t descend. I’ve also seen almost 11-pound babies born vaginally.
HOW you labor is more important than the SIZE of your baby.
My dear friend and two-time doula client, who is just over five feet tall and very petite, recently pushed out a 10 lb 9 oz baby. During labor, she moved a LOT, not staying in one position for more than a few contractions. She followed her body’s lead, pushed instinctively for only twenty minutes, and had no tearing.
You can watch her big baby birth video to see how she managed to wiggle her large baby right on out.
Options for Delivering a Large Baby
There are some risks associated with delivering large babies vaginally.
The most significant risk is shoulder dystocia, meaning the baby’s shoulders get stuck in the birth canal after the baby’s head has been born. 99.8% of the time, shoulder dystocia is resolved quickly and without permanent damage to the mother or baby.
Babies larger than 9 pounds may also cause vaginal tearing, have trouble regulating their blood sugar, and are at higher risk for jaundice.
Keep in mind, these risks are for babies that are actually larger than 9 pounds, not those who are only suspected to be.
When considering your birth options, it is important to know the risks associated with Cesarean birth, vaginal birth, and induction. Your preference should significantly impact what your provider recommends if they suspect your baby will be big.
C-section for a Big Baby
Big babies don’t always need a Cesarean. Unless there is a medical reason for C-section, besides a suspected large baby, a trial of labor should be considered for parents who want it, whether for VBAC (TOLAC), first-time moms, or 4th and 5th deliveries.
It would take nearly 3,700 Cesarean deliveries to prevent one permanent injury due to shoulder dystocia. Cesareans are associated with higher rates of complications for both mother and baby. For this reason, ACOG recommends elective Cesareans only be performed when a baby’s size is estimated to be greater than 11 pounds.
However, there may be instances where a Cesarean birth is more beneficial for mother and baby. The birthing person may even choose to have a Cesarean after weighing the risks and benefits. That is ok. Some reasons you might consider a Cesarean for a suspected baby may be:
- The baby is estimated to be larger than 11 pounds
- Reduced risk of vaginal birth trauma
- Avoiding the risk for and injuries due to shoulder dystocia
- Uncontrolled gestational diabetes
- Wanting to avoid the possibility of an operative vaginal delivery
- Avoiding the discomforts of labor
- The preference of the person giving birth
Vaginal Birth for a Big Baby
As discussed above, a suspected big baby is not a reason to automatically schedule a Cesarean or induction. Plenty of parents give birth to babies larger than nine pounds without complication or permanent injury.
Vaginal delivery is associated with fewer complications for both parent and baby and will decrease the likelihood of complications in future pregnancies. Some parents desire these and other benefits of a natural birth.
Some reasons you might choose vaginal birth include:
- The odds of NOT having shoulder dystocia are roughly 93% for babies between 9 and 11 pounds
- The desire to avoid major surgery and the potential complications associated with it
- Shorter hospital stay
- Better chances of breastfeeding and bonding with the baby right away
- Quicker recovery
- Babies born vaginally tend to have stronger immune systems
- Less likely to have complications in future pregnancies
5 Tips To Get That Big Baby Out Without a C-Section
The good news is, regardless of whether your baby is big or not after birth, there are a lot of things you can do to deliver a suspected big baby vaginally.
Being informed of the risks associated with macrosomia, Cesarean, induction, and vaginal birth is a great start.
Here are five ways to approach your birth as confidently and prepared as possible to deliver a large baby.
1. Know the Facts About Macrosomia
We discussed the increased risks that come with big babies above. Get familiar with those facts and know the risks ahead of time. Understanding the likelihood that your baby will even be on the large side will help as you make decisions about your care with your provider.
It’s essential to know the facts about vaginal birth and VBAC with gestational diabetes. Providers are more prone to induce or schedule a Cesarean at 39 weeks for a suspected big baby with gestational diabetes, despite it not being evidence-based.
Taking a birth class will benefit you greatly; knowing what to expect during pregnancy and labor will give you a well-rounded knowledge of birth.
2. Hire a Doula
Studies show that having a doula improves just about every aspect of your birth, and delivering a large baby is no exception.
A skilled doula helps a woman communicate her needs and perceptions to realize her dream of having a healthy, positive birth experience.
Guess what else? Having a doula is shown to reduce your chances of cesarean by 39%! And you can find even more doula statistics here.
A great doula will help you learn how to encourage your baby into an optimal position and prepare your pelvis for birth. They will help you with labor positions to open your pelvis and help get your baby out, no matter what the size.
A doula is your advocate, can see when things might be headed towards unnecessary interventions, and help you find your voice both in pregnancy and during delivery.
3. Move, Move, Move!
The WORST position to labor in, especially when dealing with large or less than optimally positioned babies, is on your back.
Being on your back can close your pelvic opening up to 30%.
Many other positions are great to labor in, helping open the pelvis nice and wide to allow even a big baby to get through. There are even great positions to labor in if you choose to have an epidural during your birth.
Moving during labor is one of the most crucial things you can do to get a big baby out vaginally and avoid a Cesarean, no matter the baby’s size. If all else fails, just remember to change positions every five contractions.
Even small changes in position, like putting a peanut ball between your knees and then taking it out, count and are possible with or without an epidural. Keeping that pelvis movin’ and groovin’ is essential.
4. Ditch the Epidural
Not everyone wants to or can have an unmedicated birth. That is ok!
If you want to get an epidural, and you think you might be delivering a large baby, wait as long as possible before you get it. Labor at home for as long as you safely can before heading to your birthplace to receive the epidural.
Epidurals not only keep you lying down and make it harder to move, but lead to other interventions such as an IV, continuous monitoring, and a bladder catheter. These interventions can further complicate things when dealing with a big baby or a baby in a less than optimal position.
So, if you are planning on getting an epidural, try and hold off until you are in active labor and have a nice, strong contraction pattern.
There ARE times, of course, when getting an epidural may help a woman have a vaginal birth if she is exhausted or has been laboring for a long time. It can be just the thing needed to help you relax enough to have a good nap, then wake up and have a baby.
It is worth weighing the pros and cons if you get to that point in your labor. (Did I mention how a doula can help you with that choice?)
5. Believe in Your Body
Sometimes there are circumstances where a baby just won’t come out vaginally, no matter how much you believe it will. However, there is a lot to be said about the power of the mind and a woman’s intuition towards having an empowering birth experience.
Belief in yourself and your ability to give birth is a massive chunk of the battle. Fear-based decisions do not belong in your birth space. Where there is fear, there is tension and, when you release that doubt and fear to bring in full confidence, amazing things can happen!
Ready to Deliver Your Large Baby?
Macrosomia can cause problems for mother and baby, but it is important to remember that the more significant majority of big babies are born without incident.
Birthing a big baby is manageable and possible — just remember to stock up on some extra large diapers!!
Want to be fully prepared for your VBAC? Check out our Ultimate VBAC Course for Parents, and learn everything there is to know about vaginal birth after a Cesarean.