What to Know About Baby Formula and Constipation

Formula-fed babies are more likely to experience constipation, so is there such thing as a "best formula" for constipated babies? Pediatricians weigh in.

Man feeding his baby with a bottle of milk while sitting on the bed in the bedroom at home.

nomad studio/Stocksy

Pediatricians get a lot of questions about poop. A big one: Is my baby constipated? After all, it can be hard to know, and there's a lot of variation in what's considered healthy for bowel movements. Babies can go days between poops and be totally fine or go "number two" every day but have trouble passing their stools, explains Joanna Dolgoff, M.D., a pediatrician and spokesperson for the American Academy of Pediatrics (AAP).

Regardless, if you're concerned about your baby's digestion, it's only natural to wonder if nutrition is playing a role. Breastfed/chestfed infants are less likely to experience constipation than formula-fed babies, doctors say. (It's also worth noting that it's common for breastfed babies to have infrequent stools around the age of 2 weeks, which is not the same as constipation, as long as the stool is soft and the baby is not straining.)

So what causes constipation in formula-fed babies? Here's one thought: Formula is thicker than human milk, so it can take longer to pass through the gastrointestinal tract, says Katherine Williamson, M.D., a board-certified pediatrician at CHOC Children's in Orange, California.

Spotting constipation in babies isn't always the easiest task—and alleviating formula-fed baby constipation isn't as simple as switching formulas (read: there's no best formula for constipated babies).

Read on to learn what pediatricians say about the relationship between infant formula and constipation and how to spot (and treat) a digestion issue with your little one.

How To Know if Your Baby Is Constipated

Constipation in children from 6 months to 4 years of age is defined by two or more of the following characteristics:

  • Less than two defecations per week
  • Excessive stool retention
  • Painful or hard bowel movements
  • Large-diameter stools
  • Large fecal mass in the rectum

Some parents think constipation means less frequent stool or straining. But straining or getting red in the face passing stool can actually be quite normal assuming the texture of the stool is soft. The baby is just learning to use their muscles.

That said, babies with constipation generally do have less frequent bowel movements than normal, says Dr. Dolgoff. So what's normal?

A breastfed baby might go multiple times a day or as little as once every five days, whereas formula-fed babies can go anywhere from one to three times a day to every few days, she says. Constipated babies also tend to have large, difficult, painful bowel movements that often look like pellets. They may arch their backs, tighten their buttocks, or cry while going.

But keep this in mind, too: "Most babies aren't constipated," says Rachel Dawkins, M.D., a pediatrician at Johns Hopkins All Children's Hospital in St. Petersburg, Florida. Constipation is certainly a possibility, but your baby might actually just be straining or experiencing colic, which can cause crying and discomfort. A milk protein allergy, lactose intolerance, or, rarely, other underlying medical conditions could also be at play, she says.

The Best Baby Formula for Constipation

If you think your formula-fed baby is constipated, a slew of questions are likely going through your head: Does powder formula make babies constipated? Does changing baby formula cause constipation? Can ingredients like palm olein oil contribute to constipation?

First: There's no one formula that's been shown to decrease or prevent constipation and there's no best baby formula for constipation, says Dr. Dolgoff. "According to the AAP, changing the formula is not necessarily what's going to help treat constipation."

By switching formulas unnecessarily, you might just be honing in on a solution that's not all that effective, too, says Bhavana Arora, M.D., a pediatrician and medical director of the CHLA Health Network, a group of more than 160 L.A.-based community pediatricians. Or worse: Changing your baby's formula could potentially cause constipation, contributing to abdominal discomfort as the baby's GI system has to adjust to the change, says Dr. Dawkins.

That's why doctors don't usually suggest changing formula without knowing exactly what's causing symptoms.

When Switching Formulas Could Help

While switching formulas isn't typically the first line of defense for baby constipation, there are some specific situations where pediatricians might suggest a formula change. Read about them below.

Your child has a milk allergy.

Signs of a true milk protein allergy might include blood or mucus in your baby's stool or an extremely fussy baby, says Dr. Williamson (though you always want to get a milk allergy confirmed before switching formulas). Only about 5% to 7% of formula-fed babies have a cow's milk allergy, but in the case your baby is one of the few, your doctor might recommend a hypoallergenic option such as Enfamil's Nutramigen.

It's not always enough to switch to a soy-based formula either. Many kids who are allergic to milk are also allergic to soy, says Dr. Arora. And it's probably worth noting that if you're wondering whether a soy formula is making your baby constipated, barring an allergy, it's likely not, experts say.

Your child has acid reflux.

Almost all babies have some amount of reflux or spitting up, says Dr. Dawkins, and is sometimes a result of over-feeding or not keeping the baby upright after feeds. That said, there are infant formulas for reflux. These formulas usually have added rice proteins to thicken them.

"The idea is that it's harder for the formula to go down and come back up," explains Dr. Williamson. "This won't help all babies, but trying a specialized formula, under the supervision of your pediatrician, won't cause harm."

When Not to Switch Formulas

Here's another formula-related question pediatricians get every so often: Can iron in baby formula cause constipation?

The worry makes sense: After all, when adults take iron supplements, they can get constipated as a side effect. But iron is extremely important for infant growth and brain development, so you don't want to switch to a low-iron formula, says Dr. Dawkins.

"The American Academy of Pediatrics has recommended again and again that all infants getting formula and not breast milk, receive iron-fortified formula to prevent iron deficiency anemia," says Dr. Dawkins.

Tips for Easing Constipation in Babies

First, it's always best to consult a health care provider if you suspect constipation. This way, you can identify potential allergies, rule out other underlying causes, determine that the issue is indeed constipation, and find a solution that works for your baby.

There are things you can do at home under the guidance of a doctor to help the problem, too. Dr. Dolgoff suggests that you start with the following:

  • If your baby is at least 4 months old and your pediatrician approves, try offering 100% prune, apple, or pear juice for two weeks. Babies 4 to 8 months old should get just 2 to 4 ounces while babies 8 to 12 months can have up to 6 ounces. However, it's worth noting that the AAP recommends that children under a year should not consume juice unless it's a medical necessity, so please consult with a health care provider to see if your situation warrants it. Alternatively, you could consider pureed fruit, but again, please check with a provider first.
  • Try offering high-fiber baby foods like barley cereal, sweet potatoes, prunes, pears, peas, beans, and broccoli.
  • In the case of more severe constipation, you can ask your doctor about Miralax (polyethylene glycol), which is a safe and effective laxative when taken under the guidance of a doctor.
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