One of the most common infant complaints in the pediatrician’s office is that a baby spits up. Some moms worry endlessly—and often, needlessly—about this issue, but a little dose of demystification and a bit of reassurance can go a long way. I hope this helps.

The medical term for spit-up is “gastroesophageal reflux,” which, roughly translated into normal-people-speak, means that stuff from the stomach comes back up the food tube. (This term differentiates it from “gastroesophageal reflux disease,” which should be used only when the reflux is causing some sort of harm; it’s often overused.) Here’s the drawing I typically make for parents (sorry, it’s not on exam table paper, but you’re not paying for it either):

Let me run through the diagram with you: Your baby drinks milk (if he doesn’t, he should). The milk travels down the esophagus to the stomach. It hangs out for a bit while digestion starts and is slowly squeezed into the intestine through that little narrow part on the drawing (called the pyloric sphincter). In the intestine, the milk is broken down, nutrients and water are absorbed, and it is miraculously processed into that lovely substance that stinks up your Diaper Genie. Sometimes, milk comes back up from the stomach to the esophagus, and out your baby’s mouth. Not a big deal.

Here’s why spit happens:

1. A baby’s stomach is TINY. When an infant is born, her stomach is the size of a cherry and holds about a quarter of an ounce. It doesn’t take much to fill that up. In our hospital, many of the physicians and nurses wear wooden “belly balls” on our name badges to illustrate this to parents (most of whom refuse to believe us).
2. Milk goes into the stomach faster than it goes out. Look at the arrows in the top drawing; I made them different sizes on purpose. Your baby might suck milk down his esophagus like nobody’s business, but then it sits in the stomach until it is slowly released into the intestines through a bottleneck called the pyloric sphincter.
3. This stream flows both ways. There’s another muscle, called the lower esophageal sphincter, between the esophagus and stomach. It’s supposed to keep things from flowing backwards, but in babies it doesn’t work very well yet. So I didn’t draw it.
4. Gravity pulls stuff down. (Really it pulls it towards the earth’s center of gravity, but most of us call that “down.”) If babies could stand up, this would be less of a problem, but when you lay them down, it runs back out—just like the bottom picture.

All these factors combine to make it very likely that your baby will spit up.

So what should you do? Laundry—lots of it. One of my mentors likes to tell parents that “Reflux isn’t a medical problem; it’s a laundry problem.” Buy some bibs, burp cloths, and spare onesies. Wash them frequently. Keep a spare shirt for yourself in your diaper bag (or just wear it proudly).

Aside from doing laundry, you can try a few other things to help:

1. Don’t overfeed your baby. One of the biggest concerns is that “he’s not getting enough.” This usually leads to a follow-up feed, which is promptly regurgitated because the kid’s stomach just can’t hold any more. If he’s eating and staying on the growth chart, he’s going to make it.
2. Burp during and after feeds. Air in the stomach leaves even less room for milk and increases the pressure that pushes it back out. Burping can be tricky, though. A lot of dads have it figured out, but moms are usually worried about breaking their baby. Obviously, we’re not trying to leave bruises or cause organ damage, but a few solid thumps with a cupped hand in the middle of the back usually does the trick. This cute little “pat-pat-pat” stuff is crap. Sometimes babies don’t burp, and that’s ok.
3. Keep your baby upright for 20-30 minutes after feeds. This will let gravity be your friend and keep the milk from running back out of your baby’s mouth. She probably can’t stand up yet, so you’ll need to hold her. Neither of you should mind this too much.
4. Elevate the head of the crib. Here’s the trick though—we don’t want anything on top of a firm, flat mattress (besides a fitted crib sheet). So that usually leaves 2 options: you can place stable supports under two of the crib legs, or you can make a wedge under the mattress out of a piece of plywood cut to the correct size. The lumber guy at your local home improvement store might cut it for free if you take your baby with you.
5. Avoid “scrunching.” A lot of parents will try placing a baby in a car seat or infant swing because it keeps her from being flat. The problem is that bending at the waist can put pressure on the stomach and make things worse.

Here are a few things to remember:

1. It looks like a lot more than it really is. Here’s an experiment that I usually ask worried moms to do as homework, but I did it for you to save you the mess. These pictures are of one ounce of milk, shown on a hard surface and on my t-shirt. We tend to overestimate the volume of liquid on a flat surface.

2. It gets better. Well, really, it might get worse first during the first few months of life. But sometime between 6 and 12 months, reflux tends to improve greatly or resolve completely. Not a lot of second-graders spit up.

3. Most babies that spit up are “happy spitters.” This issue tends to bother moms (who have to do the laundry) more than their babies. If your baby smiles while he spits up, don’t worry about him.

4. “Curdled” spit-up isn’t bad. That’s just what milk looks like after simmering in stomach acid. You can try this experiment on your own with milk and vinegar. It’s also not more severe because it comes out of the baby’s nose–those holes are connected.

When to talk to your doctor:

1. If your baby isn’t gaining weight well. This could be a sign that there is something more serious going on; it may need further investigation.
2. If your baby appears to be in pain when spitting up. Some babies will arch their backs or scream excessively. There are medicines we can use for this. They typically don’t make babies stop spitting, but they can make it less painful.
3. If your baby spits up anything red or green. Milk goes in white; it should be about the same color when it comes back up. Christmas colors are generally bad.

And as always, contact your pediatrician if you have any other questions or concerns about your baby’s health, growth, or development. It’s what we do.

The “Spit Happens” bib photo above is used by permission. Check out this and Meghan’s other work at Sew So Darling. Thanks, Meghan!