You've had your baby home a month or so, and he's a cutie--no doubt about it. There's one problem though, a problem you hadn't considered before he arrived: He pukes all the time! And it's not just a little urp. We're talking over your shoulder and through his nose kind of stuff. You're embarrassed to let others hold him. Aunt Betty, the one who always knows best, thinks your baby needs to see a specialist right away, and your neighbor tells you she knows someone who knows someone who had a spitty baby who choked and died in her sleep.

You start making middle-of-the-night nursery runs to check your baby's breathing. The baby monitor is turned up so loud you can hear its electric hum, and you promise yourself once more that in the morning you really are going to call the doctor and ask to see a specialist. In the meantime, your baby is asleep. There's no unusual sound on the monitor, and no vomit in the crib. Your baby is fine, but the situation is driving you crazy.

So is this spitting-up okay? Or is it a problem?

Most of the time, baby spit-up is a temporary form of gastroesophageal reflux disease (GERD). It's a condition caused by a loose valve on top of the stomach. From a mechanical point of view, the stomach is pretty simple. Food goes in, mixes with acidic digestive juice, and gets churned. Then the stomach gives a great big squeeze, forcing food into the small intestine.

For many, this is the problem stage. When the stomach squeezes, the valve on the bottom is supposed to open, and the valve on top is supposed to stay closed. But in babies with GERD, the valve on top also pops open, so food goes both ways--up and down.

Unfortunately, GERD is not the only cause of infant vomiting. There are life threatening causes as well. Bowel obstruction. Infection. Metabolic disease (such as PKU). So how do you tell the difference? Well, you don't do it alone. You find a doctor you trust and you let her decide. Here are some questions she'll ask:

Is the spit-up projectile? Bowel obstructions create a great deal of pressure. These babies have very forceful vomiting, often across the room.

Is there blood or bile in the vomit? These are serious signs. Blood may indicate erosions or high blood pressure in the GI tract, and bile is common with obstruction.

Does your baby choke on the spit-ups? We're talking more than a little red-in-the-face gag here. If your baby is having pauses in breathing or is dusky blue in the face, you should seek medical help immediately. While severe reflux can cause this problem, heart defects, blood infections and meningitis can too.

Is your baby gaining weight appropriately? Severe reflux can cause weight loss, but your doctor will want to eliminate other possibilities.

Your answers to these questions, along with physical exam findings, will determine the next step. If there is a reason to suspect a cause other than reflux, some testing is likely. The most common test is the "upper GI." Your baby drinks a bottle of barium, and the radiologist takes x-rays. The barium lights up, showing the structure of the intestinal tract. If all goes well, your baby will have a little spit-up action during the exam. The radiologist will see the reflux as it occurs, and you'll have your culprit. On the other hand, your baby might not cooperate. He might not show any reflux during the test even when reflux really is the cause of the problem. Don't worry; it won't be the last time he refuses to show off for you.

Other tests are possible, but only a handful of babies need them. For most, reflux can be diagnosed on the basis of the history and physical alone. It's like my grandma used to say: If it looks like a duck and walks like a duck and quacks like a duck, it's probably a duck.

So let's say we establish that your baby has reflux. What's next? How do you make it go away? After all, that's the question that brought you in. Well, you might not like the answer. The answer is you do nothing, unless the reflux is causing a problem. Dirty laundry doesn't count here. We're talking constant fussiness or breathing difficulty or weight loss.

For fussiness, something to reduce stomach acid usually does the trick--antacids and Zantac are good examples. Your baby will still spit up, but at least he'll smile at Aunt Betty as he soils her blouse. Babies with breathing problems or weight loss are a more difficult bunch. They need reduction of their vomiting.

You can start by decreasing feed volume. Refluxing infants tolerate 2 ounces every 2 hours better than 4 ounces every 4 hours. Also, try to keep your baby upright during and after feedings. This allows gravity to keep milk in the bottom portion of the stomach. Your doctor may have you add rice cereal to the milk. Not Rice Krispies. Rice baby cereal. Don't laugh. I've seen it done. Thicker milk stays down better, but it comes with a price--weight gain.

Sometimes these simple measures aren't enough. Your baby may need medicine and possibly surgery to stop the vomiting. This is reserved for the most severe cases of reflux. Medicine and surgery may have side effects and unexpected results, so it's best to make sure their potential benefit outweighs the risk of consequences. Your doctor will help you decide.

For most babies, reflux treatment is not necessary. These are the babies without projectile vomiting. There is no blood or bile in their spit-ups. They aren't choking. They have no breathing difficulty. No weight loss. No extreme fussiness. It's okay to let their milk fly over the shoulder or out the nose. It's even okay if it soils Aunt Betty's blouse. What you have there is not a baby problem. It's a laundry problem--and that's something Aunt Betty knows all about.