An Economist Analyzed the Data and Found This Is the Best Age to Potty Train

Photo credit: Getty
Photo credit: Getty

From Good Housekeeping

When it comes to raising kids, new parents learn right away that there's no shortage of advice. From friends and relatives to doctors, books, and message boards, everybody has an opinion about the best way to bring up your children. So, how do you know which advice is actually worth following?

If you prefer a "just the facts, ma'am" approach to parenting, consider the new book Cribsheet: A Data-Driven Guide to Better, More Relaxed Parenting, From Birth to Preschool written by Emily Oster, Ph.D. A professor of economics at Brown University, she analyzed studies and reports to find out which conventional-wisdom "rules" of parenting actually had data to back them up, and which didn't — often with surprising results.

From the true benefits of breastfeeding to the best age to potty train your child, many of her findings go against the status quo. We spoke to Oster about some of her findings; test your knowledge by seeing if you can correctly guess what Oster's research reveals.


A: Unfortunately, breastfeeding won't put your kid on the fast-track to an Ivy League. According to Oster, the data doesn't point to there being benefits to breastfeeding as your kid gets older. "To the extent that there are benefits to breastfeeding, I think the ones that we have evidence for come early on in life," she says. "We see things like impacts on digestion, impacts on allergies. We look at things like IQ, weight, or other kinds of long-term outcomes, and there's just no good evidence suggesting that breastfeeding improves those outcomes." So, if you were breastfeeding just because you thought you'd be missing out on a leg-up that breastfed kids get, you can throw out your pump now.

Of course, there's nothing wrong with breastfeeding, so if it works well for you and your baby, there's no reason to stop. In fact, breastfeeding may actually be healthier in the long run for you: studies show links between breastfeeding and reduced risks of breast cancer.


Good news, moms: You don't necessarily have to ditch your hard-earned breast milk after drinking. If you're not tipsy, your baby won't be, either. "The concentration of alcohol in your breast milk is the same as the concentration in your blood," Oster says. Once your body processes the alcohol, it's gone from both your blood and your breast milk. "I think people have this idea that the milk builds up in your breast and is stored there," Oster says, "and that's not the way it works."

If you've only had one drink, it's most likely fine for you to breastfeed your baby. "Unless you were drinking quite a lot, the concentration of alcohol in breast milk is really, really low," Oster says. "There isn't any particular evidence that it's problematic. If you're only going to have one drink, the concentration of alcohol in your breast milk is comparable to the concentration of alcohol in orange juice."


A: This is kind of a trick question, in that it really depends on quickly you want to get it done. "Basically, potty training is dealer's choice," Oster says. "If you start when your child is younger, it'll take you longer, on average."

The book notes that if you start potty training at around 27 months, you'll probably be done by age 3, so you'll be in for around nine months of training. If you start when your child is older, at around age 3, you'll probably be able to do it in just six months, but you'll still be changing diapers well after her third birthday.

The bottom line: If your goal is to ditch the diapers ASAP, you might want to begin potty training earlier. If you'd rather spend less time on potty-training, you can wait a little longer to get started (until the age when M&M bribes might start to work).


A: "The answer here is basically no more than four months," Oster says. "The evidence that sharing a room decreases the risk of SIDS is not very high quality to begin with. Then, after four months, you're into the period that the risk of SIDS is very low, and there's evidence that kids who sleep outside their parents' room sleep better at 4 months, 9 months, and even beyond that."

This is an interesting finding, because it runs counter to what the American Academy of Pediatrics (AAP) has historically recommended: When they updated their guidelines on safe sleep in 2016, they said that parents and children should share a room for at least 6 months, and ideally up to to a year.

After parents, caregivers, and doctors caused an uproar, saying that room-sharing would cause a huge decrease in the amount of sleep parents get, the organization admitted that more research was needed on the subject. Now, thanks to Cribsheet, we know that research suggests a much shorter timeline than the one recommended by the AAP.


A: It may make you feel awful in the moment, but letting your child cry it out may actually be a good thing. "There's no evidence that it harms your kid in the long run or in the short run," Oster says. "On average, it improves infant sleep."

On top of that, it may also be beneficial for moms and dads. "On average, the cry-it-out method lowers rates of depression in parents," Oster says. "We have a lot of discussions about the impacts of sleep training which all focus on the kids, and we ignore the fact that some of the reason for doing this is that not sleeping for parents is really hard. It causes them to be tired and depressed, and that can be dangerous." She says that studies focusing on maternal mood and marital satisfaction show definite benefits associated with the cry-it-out method, so it might even save you some tears in the end.


Another trick question: "There's no ideal," Oster says. "There isn't any evidence that it matters in terms of the health of your kids, or even their development." This comes with the caveat that babies spaced very close together might affect a mother's health, since she'd have to go through another pregnancy shortly after giving birth.

Want the hard facts behind other parenting myths out there? Pick up Oster's book to learn more and figure out exactly what's right for you and your family.

You Might Also Like