8 Scientific Studies That Could Change the Way You're Raising Your Kid

Breakthroughs in children's medical research dominate the news, but it's not always easy to know which findings are worth your attention. Consider this your cheat sheet.

peanut powder, marijuana leaf, kids of varying heights
Getty Images (2); Adobe Stock (1).

In a world of 24/7 news, keeping up with the latest advice about children's health and development can be overwhelming. (Let's face it; some days it's a win just to make time to floss.) Plus, it's impossible to decide which study du jour to trust: Should you give your kids vitamins? Yes. No. Maybe. Repeat.

To keep you from falling down a rabbit hole, we asked leading pediatricians and medical-journal editors to share the recent studies that savvy parents should have on their radar. Of course, research is ongoing, and scientific consensus can happen at a snail's pace. But these findings highlight key emerging trends in our understanding of children's physical and emotional well-being—and they may help you raise healthier kids.

Probiotics can soothe colic.

The research: A large review of smaller studies found that giving colicky babies daily drops of the probiotic Lactobacillus reuteri significantly reduced minutes-per-day of crying and fussing in breastfed infants over a three-week treatment period as compared with babies given a placebo. The same benefit wasn't found for formula-fed infants with colic.

Why it's important: "The microbiome—the blend of good and bad bugs that live in our gut—is an exciting area of research," explains Alex Kemper, M.D., professor of pediatrics at Nationwide Children's Hospital, in Columbus, Ohio, and deputy editor of Pediatrics. Probiotics contain microorganisms that are the same as or similar to the beneficial bacteria in our intestines that crowd out illness-causing bacteria, and they can also reduce inflammation. (Breastfed infants may have different gut populations from formula-fed babies, which could be why they didn't benefit equally in this review.)

While some research has suggested that probiotics may be helpful for everything from protecting preemies from serious intestinal infections to heading off eczema in older kids, other studies have not found a clear benefit. "We are a long way from being able to say, 'Take this type of probiotic for this condition,'" says Dr. Kemper. "For now, if your child needs to take an antibiotic, talk to your doctor about choosing one with the narrowest spectrum possible so you don't kill off the good bacteria with the bad." If you want to try L. reuteri for your own fussy breastfed baby, talk to your pediatrician. The study found no harm from the treatment, so it may be worth a try.

Spanking causes lasting damage.

The research: In a research review in American Psychologist, a panel of top experts concluded that spanking causes the same psychological harm to children as hitting, slapping, and other means of inflicting pain. Spanking also doesn't improve kids' behavior at home, and it increases the rate of behavior problems reported by teachers. Adults who were spanked as children are more likely to use drugs, have a drinking problem, and commit suicide, compared with those who weren't spanked.

Why it's important: Giving a child a slap on the bottom when he misbehaves is still a surprisingly common go-to. One estimate found that 80 percent of parents do it on occasion. "Parents can fall back on how they were parented. They say, 'This is what my parents did, and I turned out okay,' " notes David L. Hill, M.D., a Parents advisor and spokesperson for the American Academy of Pediatrics (AAP). "So I tell them, 'I am so glad you did! But we have a lot more information now about better ways to do things.'" Last year, the AAP issued its most strongly worded policy statement, saying that spanking can cause harm and parents should never hit a child. Try to guide kids' behavior in ways that build your bond rather than fray it, advises Dr. Hill. "Praise the behavior you do like, especially when that thing is hard for your child. The more you call attention to the good stuff, the more of it you'll see."

Marijuana lingers in breast milk.

The research: Fifty nursing moms who regularly use marijuana donated breastmilk samples to the Mommy's Milk Human Milk Research Biorepository, at the University of California, San Diego. Traces of THC (tetrahydrocannabinol), the primary psychoactive component of marijuana, were found in 63 percent of the samples up to six full days after the mom's last reported use, according to a study in Pediatrics.

Why it's important: Now that more states are legalizing it, moms may think of marijuana as a relatively harmless way for them to de-stress. Plus, some pregnant women use it to quell morning sickness. But THC likes to bind to fat molecules, which are abundant in breast milk. "Almost nothing is known about the effects of marijuana exposure on a baby's growing brain," says Dr. Kemper. "This particular study was one of the first to start to find evidence-based answers." Even though THC levels were found to be low in the breast-milk samples, marijuana still lingers in the body, so pumping and dumping after using weed is not a reliable strategy. For now, the AAP advises that you play it safe and not use marijuana while pregnant or breastfeeding.

Peanut powder may prevent life-threatening reactions.

The research: Taking a small daily dose of peanut-protein powder allowed severely allergic children ages 4 to 17 to gradually build up their tolerance to peanuts. After about 12 months of treatment, two thirds of the kids were able to tolerate the equivalent of eating two peanuts with no more than mild symptoms, according to a clinical trial published in the New England Journal of Medicine.

Why it's important: For kids who have a peanut allergy, a birthday party or a chance encounter with the wrong cookie can mean a scary trip to the emergency room. The treatment studied is the first of its kind aimed at preventing anaphylactic attacks. "It doesn't mean that children with a peanut allergy will be able to sit down and eat a jar of peanut butter, but it could mean that they won't have a life-threatening reaction if they reach into a bag that has Reese's Pieces candies in it," says Angela Castellanos, M.D., a pediatrician and editorial fellow at the New England Journal of Medicine. There are still concerns and questions: Some of the kids in the treatment group had significant allergic reactions requiring medical intervention and close medical supervision. And doctors don't know if kids will need to continue treatment with the peanut protein for the rest of their life in order to retain the tolerance. The manufacturer is awaiting FDA approval to market the peanut powder in prescription form, which would be given to kids in a special protocol supervised by their doctor.

Girls’ pain is taken less seriously than boys’.

The research: Adult subjects watched the same video of a child's upset reaction to receiving a finger stick at a pre-K checkup. The gender of the child was unclear in the film, and those who thought the child was "Samuel" (a boy) rated the child as being in more pain than those who believed they saw "Samantha" (a girl). The Yale University researchers attributed the difference to stereotypical beliefs such as "Boys are more stoic" and "Girls are more emotive."

Why it's important: Ouch. Previous research has found that doctors often treat adult women's pain differently from men's. Though preliminary, the study suggests that this disparity may start all too early. And because little kids often lack the vocabulary to describe their pain, other people's accurate interpretations of their emotions are particularly important.

True, it may take a while to overturn the patriarchy. But being aware of this kind of bias can help you become a better advocate for your own child, says Dr. Hill. "No pediatrician gets up in the morning and says, 'I am going to treat a boy's pain differently from a girl's.' But doctors are human, and we can bring all kinds of assumptions when we interpret what's going on with any individual patient. One of the most important things a parent can do is tell the doctor, 'I know my child, and she is not usually like this. She hardly ever complains. She is the kind of kid who can fall off her bike and get back up, laughing.' As pediatricians, we put a huge amount of stock in that kind of statement."

Parents’ actions can ease or enable a child’s anxiety.

The research: More than 100 kids ages 7 to 14 with anxiety disorders were given cognitive behavioral therapy (to help them learn to challenge their worried thoughts), or their parents were coached in weekly counseling sessions on strategies for reacting to their child's anxiety, such as reducing the number of reassuring text messages they sent their child. Treating the parents was just as effective in reducing their kids' anxiety levels as treating the kids directly, according to the study in the Journal of the American Academy of Child & Adolescent Psychiatry.

Why it's important: One in three children will experience a clinically significant anxiety disorder before adulthood. While therapy and medication are very effective treatments, this study reflects a growing interest in the role parents can play in helping kids cope better. "It just makes sense. Parents influence their children much more than even the best therapist," says Matthew Biel, M.D., division chief of child and adolescent psychiatry at MedStar Georgetown University Hospital, in Washington, D.C.

Loving parents can inadvertently contribute to their child's anxiety by being overly accommodating, an issue that the study's counseling sessions addressed. "If your child is afraid of dogs, you might cross the street to avoid one. If he is afraid of the dark, you might sit with him until he falls asleep," says Dr. Biel. Although this can provide immediate relief, it also teaches your child that there must truly be something to fear—and he isn't able to handle it by himself. Instead, it's better to help a child move out of his comfort zone: Encourage him to get a little closer to that friendly goldendoodle, for example, and praise his bravery when he does.

Talking with you is what builds your child’s language skills.

The research: Cognitive scientists at MIT tested the verbal skills of kids between ages 4 and 6, and recorded and analyzed how the children and their parents chatted with each other at home. The biggest factor in a child's verbal score was the number of back-and-forth exchanges he or she had with adults, not the number of individual words heard at home.

Why it's important: It was once believed that kids learned language merely by overhearing lots of it, says Jennifer Lansford, Ph.D., a research professor at the Sanford School of Public Policy at Duke University and an editor of Developmental Psychology. This study is part of a body of evidence suggesting that good old conversation with your kid is what's most important. "Starting from infancy, children learn grammar, vocabulary, and comprehension better when you talk with them than if they are just passively listening," says Dr. Lansford. The most enriching conversations follow a child's lead. For instance, if your toddler says, "Car!" reply in ways that build on that: "Yes, that is a red car. Do you see a blue car?"

Kids who are young for their grade are more likely to be diagnosed with ADHD.

The research: Many states have a cutoff birthdate of September 1 for kids to enter kindergarten. That means those who were born in August, right before the cutoff, can be nearly a year younger than classmates with a September birthday. A study in the New England Journal of Medicine using insurance data from more than 400,000 kids found that August-birthday kids in these states were diagnosed and treated for ADHD at higher rates than their peers born in September.

Why it's important: ADHD rates have climbed over the past decades, and experts don't know if that trend is partly due to overdiagnosis. The condition often first becomes apparent when kids enter school and their behavior is observed in relation to their peers. "ADHD can be tricky to assess. Teachers, parents, and doctors all work together to make the diagnosis," says Dr. Castellanos. Being 6 rather than 5 can make a big difference when it comes to being able to sit quietly, so the developmentally appropriate ants-in-the-pants of a younger kid may seem like a behavioral issue. "This study suggests we need to be thoughtful about age when we're making diagnostic and treatment decisions," Dr. Castellanos says. But the findings shouldn't be seen as a reason to redshirt all kids when considering whether to wait before starting school.

The HPV vaccine’s benefits are clear.

The research: The human papillomavirus (HPV) is a sexually transmitted infection that can cause genital warts as well as cervical, penile, and other cancers. A study in Pediatrics by researchers at the University of Cincinnati tracked 1,600 teenage girls and young women over a decade and found that those who'd been vaccinated had an 81 percent lower rate of HPV infection.

Why it's important: The shot has now been around for 13 years, but many parents remain leery of what they perceive as a newcomer. "They tell me they don't want their child to be a guinea pig," says Dr. Hill. Although the vaccination is recommended for girls and boys ages 11 to 12 (and as young as age 9), only 43 percent of adolescents have been fully vaccinated. This study provides reassuring real-world evidence that it works, says Lewis First, M.D., editor-in-chief of Pediatrics. "Getting your son or daughter vaccinated during early adolescence can greatly reduce the chance of getting certain cancers down the road." And a separate study showed that vaccinated kids are no more likely to engage in earlier or riskier sexual activity. In other words, teens aren't viewing the vaccine as the green light to start having sex or to toss the condom box. So go for the vaccine. You've got nothing to lose.

Bonus: 5 Smaller Studies You Should Also Know

Hiding negative emotions isn't always a good thing.

When moms and kids completed a frustrating Lego task together, kids were more upbeat if their mom expressed her own negative emotions about the task in a healthy way rather than trying to hide them, found a study from Washington State University. So give up that Pollyanna act. Kids pick up on your moods, and it's confusing when you try to act like everything's fine.

Music can make your bond stronger.

Time to crank up Spotify! Kids who grew up listening to music together with their parents reported better relationships with them when they reached young adulthood, according to a study published in the Journal of Family Communication.

Nighttime wakers aren't behind other 1-year-olds.

A Pediatrics study found that 43 percent of 1-year-olds still don't sleep eight consecutive hours at night. (You're not alone!) Reassuringly, nighttime wakers were on track with their solid-sleeping peers on measures of cognitive, language, and motor development.

Girls prefer their foods to be separate.

Kids often freak if their carrots touch their potatoes, and science shows a gender bias may be at play: A study from the University of Copenhagen found that 7- and 8-year-old girls preferred their foods to be separate rather than mixed, but boys didn't care. Maybe the boys were hungrier?

Print books boost parent and toddler interaction.

Nothing beats a dog-eared Dr. Seuss fave. A study from the University of Michigan found that parents and toddlers talked and interacted more when they read a print book together rather than an e-book. When reading from a screen, parents were less likely to ask questions or make comments about the story line.

This article originally appeared in Parents Magazine as "New Science That Could Change the Way You Parent."

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