Ask any new or veteran mom, and she’ll tell you there’s a huge difference between birthing a small baby and a large baby. So how can parents predict which end of the spectrum their infants will fall on?
There are plenty of signs that tell us all kinds of details about our babies while they’re still in the womb. From what sounds, smells, and even sights they respond to (did you know babies can see light from within the womb?), we learn about their personalities and preferences. From checking their growth and development with ultrasounds and image measurements, we find out whether they’re developing normally or if they have health issues that need to be addressed.
But despite all this technology and information-seeking, our main predictor of our babies’ size—the ultrasound—is still largely inaccurate. In fact, there’s a recognized error of 15 percent in ultrasound measurements, according to Belly Belly, which means your baby can be either 15 percent heavier or lighter than what the ultrasound suggests. And that’s if your provider knows what they’re doing! Since moms can’t rely on ultrasounds alone, here are 10 other signs of big babies and 10 signs of a tinier tot.
20 Big: Mom’s Belly Is Out There
One of the first things expecting moms get excited about is their bellies beginning to grow. It’s a sign that things are going well and that your baby is likely very healthy. But if the belly is growing a bunch, that could mean things aren’t exactly normal. In general, the bigger a mom’s belly is, the more likely it is her baby will be large.
Of course, this varies among moms, but often, a bigger baby stretches things out more! There’s also fluid to account for, and the placenta, and there will be more volume of both the bigger the baby is.
19 Small: The Belly Is Tucked In
Some moms are great at hiding away their baby bellies, so that even big babies don’t appear so from the outside. But most often, moms with tiny baby bumps are harboring even tinier babies than usual. For some mamas, this might even mean you barely look pregnant!
And that’s not always a good thing—but what’s reassuring about having a small belly is the fact that it does still grow, even if it doesn’t get as big as other moms’. As long as you’re seeing growth and visiting with a care provider throughout your pregnancy, it’s likely that your baby is just a bit smaller than average.
18 Big: Running Out Of Room
When we say bigger, we don’t necessarily mean just by pounds. Sure, it’s harder to push out a ten-pound baby rather than a seven-pound one, but length is also a factor. A longer, or taller, baby will likely stretch out more in the womb—potentially making it painful for mom.
It’s not uncommon to hear moms complain that it feels like the baby’s feet are in her ribs or his head so low in her uterus that it feels like it’s going to fall out! In general, it’s bigger babies that have these issues since it’s such tight quarters.
17 Small: Not Feeling Baby Much
Though you can often still feel a small baby swimming laps in the womb, you might not be able to tell which pokes and prods are feet versus hands versus heads, even. That’s likely because there’s still plenty of room for moving around, so the baby doesn’t necessarily have to “push off” the walls of the uterus to move around.
Instead, she’s basically floating around, perhaps occasionally bumping into something, but for the most part enjoying the space to stretch out. And while she might be flopping to breech and back to head- down, along with some other variations, you might not even realize she’s doing it.
16 Big: Past Due Dates
The longer the baby cooks, the bigger she’ll be! In most cases, a baby who goes beyond her due date can be expected to be bigger than average. However, with the unpredictability of due date calculation, it’s hard to know whether your baby is truly past dates or not!
And, while most health care providers used to consider 37 weeks gestation to be full term, most providers now recognize that 40 is ideal—and even 41 or 42 produces very few risks for moms. In fact, many midwives won’t induce labor unless a mom is beyond the 42-week mark—unless there’s another health concern, of course.
15 Small: Baby’s Doing Flips
While back labor may be a sign of a bigger baby, the lack of back labor can indicate the opposite. Your baby might be smaller if you’re not feeling painful movement in your back or other areas, even as contractions begin. You may also notice the baby switching positions a lot—a baby who is breech (feet fist) may flip-flop a number of times throughout the last few weeks of pregnancy.
And while many moms worry about not being able to have a natural delivery with a breech baby, it’s entirely possible for your smaller baby to flip flop her way around and come out head first in the end.
14 Big: When Mom Has Sugar Trouble
Another sign that your baby might be larger than normal is if you have gestational diabetes. Gestational diabetes is a condition that affects expecting mom's blood sugar levels. If it’s left uncontrolled, it can negatively affect the baby, resulting in highs and lows in the baby post-birth, and even diabetes in the baby himself.
Even moms who are able to manage their blood sugar levels could wind up with a larger baby, simply because it’s a side effect of the condition. And this is true even if a woman was previously normal size—it’s not just plus-sized moms who are at risk for having larger babies because of GD.
13 Small: Contractions Come Early
Obviously, a baby who isn’t yet done “cooking” will be smaller than average—sometimes even scarily so. But some babies come on their own timetables, and though you may technically be 36 or 37 weeks pregnant, your baby will decide to make his entrance.
This is part of the unpredictability of birth and pregnancy, but it also means there’s so much up in the air until your baby actually arrives. After all, babies are still gaining pounds in the last few weeks of pregnancy, so sometimes a baby who would have been an average size arrives early and is missing a few ounces!
12 Big: Not Much Movement
Whether you have a big belly or just an average-sized one, a key sign the baby will be big is if they start to slow down with their movements. The larger the baby gets, the less room he’s got to do flip-flops inside, so the less movement you’ll feel.
This is more true toward the end of the pregnancy regardless of your baby’s size, but bigger babies will probably run out of room a lot faster than average- and smaller-sized ones. This also depends on how the baby is positioned, since there are moms who rarely feel movement at all and still deliver big—and healthy—babies.
11 Small: A Whole Lot Of Movement
It makes sense that the smaller your baby is, the more room she has to maneuver in the uterus. And with plenty of amniotic fluid, your womb might just feel like an Olympic sized pool to your baby! And, depending on where the placenta is located, it might be cushioning some of the movement, too.
You might feel more fluttering and kicking with a smaller baby toward the end of the pregnancy, whereas earlier on it was difficult to feel anything because of how much space was around her. Thankfully, this much movement from a smaller baby often isn’t as uncomfortable as a bigger baby tumbling around.
10 Big: Size Runs In The Family
If you look around at your family and everyone is over six feet tall—maybe even including you—then odds are, your baby will have the same genes. Of course, some traits skip generations, but if your family has always been tall and solidly built, there’s a pretty good chance your baby will be big from the beginning, too.
That doesn’t mean you’re looking at a solid 10-pounder, but anything above eight pounds makes sense in a family of bigger people. You can also look at what your birth size was—if you were a big baby, you can expect the same from your kiddo.
9 Small: Most Tots Are Tiny
Regardless of your own size, looking at your extended family’s offspring might also give you hints about what your baby’s size will be at birth. If your nieces and nephews are all petite babies, yours might follow the family tradition. This could also apply to cousins and their families, depending on how strong the family genes are!
Similarly, if you have older kids already and they’re all on the smaller side—or at least they were at birth—then you can likely expect more of the same. The same goes for your own birth size—if you were a smaller baby, yours could be tiny, too.
8 Big: Dad Is A Big Dude
Your partner’s size can also factor in to the equation as far as how big the baby is. If you’re more petite and your husband is exceptionally tall or husky, that could mean your baby takes after dad. But as many midwives and even doctors say, a woman’s body doesn’t generally “grow” a baby that it can’t handle—so while the birth could wind up being difficult, it’s highly unlikely you’ll wind up with a 12-pound baby if you’re 5 foot 2, even if your husband is close to seven feet tall!
You can also look to your husband’s family for clues as to what size babies generally are on his side.
7 Small: Dad Has Smaller Genes
If both you and your partner are petite, it’s almost guaranteed your baby will be, too. And even if you’re taller, it’s possible for your partner’s genes to take over and result in a smaller-than-average baby. Also think about whether the baby’s dad’s family has a history of smaller babies—often size runs in families, just as it does for bigger babies.
And some expectant moms are lucky enough to never pack on too many pounds during pregnancy just because of good genes—even though they’re eating for two (and then some)—and they wind up having petite babies that seem a bit unexpected.
6 Big: Ultrasound Shows Little Fluid
When I was 41 weeks pregnant with my second son, my midwife wanted an ultrasound to make sure the baby still had plenty of fluid. And while he was still comfy and cozy in there, the fluid did look good—although there wasn’t a ton of it, given that the baby was taking up most of the space!
Your healthcare provider can tell you that it’s important for your baby to have plenty of fluid surrounding her, but the bigger she gets, the less room there is for liquid! Plus, the fluid regenerates all the time, so unless you have another health condition, your baby probably has plenty of cushioning.
5 Small: Baby’s Got Plenty Of Water
Having sufficient amniotic fluid is important for the baby’s safety and overall wellbeing, but smaller babies tend to have extra large pools to enjoy! If your ultrasound shows plenty of fluid around the baby, you might expect a smaller tot than if there was less fluid visible.
And here’s where a previous sign may be inaccurate: a mom can still have a seemingly giant belly, with a tiny baby and a ton of fluid inside. And even ultrasound measurements can be an inaccurate predictor of size—so you can’t rely on those figures alone to determine how big or small your baby is.
4 Big: Mom’s Got Back Labor
Back labor is arguably a more excruciating form of labor than regular old contractions. But it doesn’t happen to all moms, and it depends more on the baby’s position than anything else. However, a larger baby is often positioned rather uncomfortably for mom, since he’s pretty squashed due to his cramped quarters.
This can mean he’s facing mom’s back, so every movement he makes is not only uncomfortable, but contractions squeeze him further against your spine. The good news is, even the biggest babies often reposition themselves during labor—though it usually helps if mom’s in a good position to help him (and gravity) make the exit clear.
3 Small: Mom’s Healthy And Happy
In moms who don’t have gestational diabetes, odds are a lot lower of having a large baby due to mom’s medical status. Of course, a healthy and happy mom is the first step in conceiving and delivering a heathy and happy baby, and most moms can expect their babies to be a normal size as long as they eat healthily and get moderate exercise during pregnancy.
Most doctors will suggest that expectant moms continue with their regular exercise regimens, as it can help them not only maintain a healthy size, but also help prepare for the physical demands of labor and birth.
2 Big: Baby Might Be A Boy
In general, baby boys are bigger—so if you’ve confirmed via ultrasound that you’re expecting a boy, odds are he’ll be a bit bigger than the girls born at the same gestation. Most of the time, this is clear even as kids grow—boys often get bigger faster, while girls take a bit longer to catch up physically (of course, girls mature faster emotionally, so that balances things out).
Of course, there are exceptions to every rule, but if your baby boy is otherwise healthy, you can probably expect him to be a bit bigger than average when combining both boys’ and girls’ statistics.
1 Small: Baby Is Likely A Girl
Of course, if having a boy means your baby is big, then having a girl means the baby is likely smaller. Of course, most statistics deal in averages, so the average baby is about 7.5 pounds. But baby girls, on average, are born between 5.1 and 9.7 pounds while boys are between 5.1 and 10.1, according to Mama Natural.
Of course, moms who’ve given birth before can tell you that although delivering a nine-pound seven ounce baby isn’t necessarily easy, it’s generally more pleasant than pushing out a newborn that’s over ten pounds. Good news, though, girl moms—you’re statistically less likely to deliver a ten-pounder than boy moms!
Sources: What to Expect, Belly Belly AU, Mama Natural