Cribsheet: A Data-Driven Guide to Better, More Relaxed Parenting, from Birth to Preschool (The ParentData Book 2)

by Emily Oster

The AAP says infants should sleep alone in a crib (or bassinet) and should be placed in the crib on their back to sleep. There should be nothing in the crib with the baby. Bumpers—pads that wrap around crib slats to prevent little hands or feet from getting stuck—should not be used. Infants should sleep in their own crib or bassinet—not in the parents’ bed—although the crib or bassinet should be in the room with the parents.

Among the most haunting aspects of parenting is the vulnerability that comes with having the thing you love most in the world be out of your control.

Second, we have to recognize that sleep choices have real quality-of-life impacts. If co-sleeping is the only way you can get any sleep, then you may choose to do it to preserve your mental health, ability to drive, and ability to function overall—all things that also benefit your child. And these crucial choices may outweigh a very tiny risk, even a tiny risk of a terrible thing. It’s easy to dismiss people who remind you to take care of yourself. But taking care of yourself is actually part of your responsibility.

When I was writing this book, I talked to my friend Sophie, who co-slept with her youngest child for many months. Sophie is a highly trained doctor, and clearly not ignorant of the risks of co-sleeping. She told me she didn’t make this decision lightly, and she didn’t disagree with the AAP’s guidelines. But co-sleeping was the only way her baby would sleep, so she took all the steps that have been shown to minimize the associated risks: she and her partner didn’t smoke or drink, and they took all the covers and blankets off of the bed. Even with these precautions, she accepted the possibility of a small risk.

The vast majority—up to 90 percent—of SIDS deaths occur in the first four months of life, so sleeping choices after four months are very unlikely to matter for SIDS. This also shows up in the data. The choice of sharing a room, or even sharing a bed, does not seem to affect SIDS risk after three or four months, at least for parents who are nonsmokers.24

Across virtually all studies of sleep location, the one thing that jumps out as really, really risky is babies sharing a sofa with an adult.

This paper also summarizes total sleep duration; newborns sleep an average of sixteen hours a day, which falls to thirteen or fourteen hours around one year.

In particular, one thing that doesn’t show as much variation is wake-up times. Even at around five or six months, the majority of children wake between six and eight a.m. By the time they get to age two, the range is smaller—six thirty to seven thirty a.m.

If you think your child needs a lot of sleep, you probably have to put them to bed earlier, since you cannot really get them to wake up later. If you try to schedule your child to go to bed late and sleep late into the morning, you will probably not succeed.

There are some broad guidelines for sleep schedule. Longer nighttime sleep develops around two months. Move to three regular naps around four months. Move to two regular naps around nine months. Move to one regular nap around fifteen to eighteen months. Drop napping around age three. There is tremendous variability across children, which you mostly cannot control. The most consistent schedule feature is wake-up time between six and eight a.m. Earlier bedtime = longer sleep.

The quality evaluation has several parts. First, there is effectively a checklist of questions on safety, fun, and “individualization.” Here’s a simple version: Safety No exposed outlets, cords, fans, etc. Safe cribs Written emergency plan Disposable towels available Eating area away from diaper area Toys washed each day Teacher knows about infant illnesses Fun Toys can be reached by kids Floor space available for crawlers to play

3 different types of “large-muscle materials” available (balls, rocking horse) 3 types of music materials available “Special activities” (i.e., water play, sponge painting) 3 materials for outdoor infant play Individualization Kid has own crib Each infant is assigned to one of the teachers Child development is assessed formally at least every 6 months Infants offered toys appropriate for their development level Teachers have at least 1 hour a week for team planning

Beyond this, there is simply very little concrete guidance about how to find and evaluate a nanny. Perhaps the most useful piece of advice I got in doing this was to talk to references (of course) and try to evaluate not only whether they liked the person but also whether the person doing the referring seemed like me. Were we people with similar needs?

Day care is associated with better cognitive outcomes6 and slightly worse behavior.7 The cognitive-outcome effects seem to be concentrated in care that occurs at slightly older ages. There is a variety of evidence for this last point—for example, the evidence for the effectiveness of the federal Head Start program is based on studies showing that preschool hours enhance school readiness.

Kids who are in day care are more likely to get sick.9 These are not serious illnesses, more like colds and fevers, stomach flu, and so on. On the plus side, these early exposures seem to confer some immunity, with children who were in day care for more years as toddlers having fewer colds in early elementary school.10

One of the best pieces of parenting advice I got from my friend Nancy was this: Regardless of what childcare you choose, have a plan for who is in charge when the nanny or the kid is sick. Fighting about who will miss work in the moment is a bad idea.

A 2006 review covered nineteen studies of the unfortunately named “Extinction” method—the form of “cry it out” in which you leave and do not return—of which seventeen showed improvements in sleep.3 Another fourteen studies used “Graduated Extinction”—where you come in to check on the baby at increasingly lengthy intervals—and all showed improvements. A smaller number of studies covered “Extinction with Parental Presence”—in which you stay in the room but let the child cry—and these also showed positive effects.

You could also argue that the effects of maternal depression on children are long-lasting, and therefore this intervention may have beneficial long-term effects. This seems in many ways more plausible.

We started this around ten weeks, at which point he was still eating two or three times a night, but we thought he was ready to fall asleep alone at the start of the night.

Early exposure to peanuts is now the normal recommendation, especially for children at risk for an allergy. The hope is that with wider dissemination and use of these updated recommendations, there will be fewer life-threatening peanut allergies.

And there is some reasoning behind this approach. Before four months, your baby is unlikely to be able to eat solid food—the skill is fundamentally different from nursing or drinking from a bottle—and there is no reason to give them anything other than breast milk. There is also a concern about filling their stomach with foods that, unlike breast milk and formula, do not give them the appropriate nutrients for their age.

Similarly, there is some sensibility behind the idea of waiting between food introductions. Nearly all allergies are caused by one of a few foods—milk, eggs, peanuts, and tree nuts—and it’s sensible not to introduce these foods all at the same time. But most people are not allergic to most things. Yes, you can have an allergy to peas, but this is very uncommon. This doesn’t mean there is anything wrong with the every-three-days plan, and based on other evidence that kids need to try a food a few times before they like it, there may be a reason to focus on adding new foods one at a time. On the other hand, if you plan to introduce all the foods to your kid before they are one, you’ll have to speed up at some point.

“baby-led weaning.” In this practice, instead of introducing pureed foods and feeding the kid with a spoon, you wait until they are old enough to pick up foods on their own and then have them more or less eat what your family eats.

Choking is, however, reasonably common in all babies, and people in the study were encouraged not to introduce foods that presented significant choking hazards. A four-month-old shouldn’t have large pieces of hard fruit, baby-led weaning or not.

once children are starting to eat solid foods, there is randomized evidence that repeated exposure to a food—say, giving kids pears every day for a week—increases their liking of it. This works for fruits, but also for vegetables, even bitter ones.

Kids are more likely to try to eat it with what researchers call “autonomy-supportive prompts”—things like “Try your hot dog” or “Prunes are like big raisins, so you might like them.” In contrast, they are less likely to try things if parents use “coercive-controlling prompts”—things like “If you finish your pasta, you can have ice cream” or “If you won’t eat, I’m taking away your iPad!!”

This is a setting in which going slowly is a good idea. Try a little bit at first—only one allergenic food in a given day—and see how they react. If nothing, give them a little bit more. And so on until you get up to a normal amount. And then keep these foods in the rotation.

The last one is obviously not just about infancy. Soda is strongly discouraged for infants and children (and adults). Your six-month-old does not need a Coke. Juice is more controversial (and, indeed, I recall a childhood dominated by orange juice), but generally, young children should have formula, breast milk, or (once they start eating solid foods) water. Whole fruits or fruit purees are preferable to fruit juice.

Choking hazards—nuts, whole grapes, hard candies—are also to be avoided, for obvious reasons. Babies and toddlers do choke, and these foods are more likely to lead to choking. Grapes are okay in pieces, nuts are okay in nut-butter form, and hard candies are not recommended for other reasons.

Cow’s milk is probably the most complicated recommendation, partly because it interacts with the allergen issues above. It is important to introduce some milk-based foods—yogurt, cheese—to avoid allergies. But milk itself is forbidden. The concern is that cow’s milk is not a complete infant nutrition system, and if your infant drinks a lot of milk, it will restrict formula or breast milk intake. In particular, infants who have cow’s milk as their primary milk source are more likely to be iron deficient.15 The evidence say...

Finally, honey. The concern with honey is that it could lead to infant botulism. Infant botulism is a serious disease—basically, a toxin interferes with neurological functions, including affecting the infant’s ability to breathe. It is most common under the age of six months and it is treatable, with a very high success rate. Still, the treatment is not easy: the baby typically needs to be hooked up to a breathing machine for a few days until they are able to breathe ...

Your toddler or young child does not generally need a multivitamin (no Flintstones gummies for them). If they eat only a very limited diet, it is possible a multivitamin would be necessary, but this would be unusual. Even a child who seems like a very picky eater will be getting enough vitamins to sustain them. A baby who is breastfed will get most vitamins this way as well. The two possible exceptions to this are vitamin D and iron.

Breastfed infants are also sometimes iron deficient, which can cause anemia. Breast milk is low in iron. Iron supplementation is not commonly recommended, unless the infant actually shows signs of anemia, and iron is present in rice cereal, so once your kid starts eating, this problem diminishes. Also, anemia rates are improved by delayed cord cutting (see part 1), which is a lot easier than supplementation.

Kids younger than school age get an average of six to eight colds a year, most of them between September and April.7 This works out to about one a month. These colds last on average fourteen days.8 A month is thirty days. So in the winter, on average, your kid will have a cold 50 percent of the time. On top of this, most kids end their cold with a cough that can last additional weeks. It adds up.

About a quarter of kids will have an ear infection by the age of one, and 60 percent by the age of four.9

You should also invest in a good general pediatrics book, which can do a more complete job at listing childhood symptoms than I can here. There are some references in the back; my favorite is The Portable Pediatrician for Parents by Laura Nathanson.

The American Academy of Pediatrics falls squarely in agreement with the second answer. They recommend no TV or screen time at all for children under eighteen months, and no more than an hour a day, ideally consumed with a parent, for older children. In addition, they recommend choosing “high-quality” programming, such as that featured on PBS. That would include Sesame Street, although it would also include less learning-focused shows, such as the parent-despised Canadian-export Caillou.

The authors reported the differences among the groups in math, reading, and vocabulary test scores at age six. Their results suggest that watching more TV under the age of three lowers test scores; not a huge amount, but by the equivalent of a couple of IQ points. If you are looking in this data for evidence that TV is bad, which is what the authors argue, high watching before age three seems to be an issue. However, watching TV at older ages doesn’t seem to matter. When the authors compared, say, the kids who watched only a little TV before age three and then a lot between ages three and five to the children who watched little TV before age three and little later, they found their test scores to be no different. If anything, the kids who watched more TV later had higher test scores than those who watched less.

after this, starting earlier does generally mean finishing earlier. If you start training at twenty-seven or twenty-eight months, you can expect to be done by around age three, but it will take ten months to do it. If you start at age three, you finish later, but it’ll likely take you less than six months to fully train.

These approaches are helpful through older ages, but can be used as early as two. The books have some specific guidelines for time-outs—for example, they should be shorter at younger ages and do not start until after a tantrum has ended. And they do outline some key components that are useful for very small children. For example, do not let your child use a tantrum to get what they want.

One of the main tenets of these parenting approaches is that discipline should be reserved for actual bad behavior, not for things that are merely annoying.

Learning that if you misbehave you’ll lose some privileges or some fun experience is something that will serve you well as an adult. Kids do not need to learn that if you misbehave, a stronger person will hit you.

There is adaptation for parents individually, and adaptation together. How does this baby fit into the plans I have for myself, for my career, for my leisure time? And how does it fit into our marriage?

Obviously, you’ve disagreed about things before (sponges, for example). But on the whole, these disagreements were not as important, and there were not as many of them. The worst thing that happens with a wet sponge is you have to replace it. But if you mess up your kid, that’s forever! The stakes seem infinitely high.

Some small-scale randomized interventions do show some effectiveness. One is the “marriage checkup.”16 The idea behind this is to have an annual meeting—possibly facilitated by some professional—to actually discuss your marriage. What do you feel is working? What isn’t working? Are there particular areas of concern or unhappiness? These checkups seem to result in improvements in intimacy (i.e., sex) and marital satisfaction. This makes sense in the abstract; it’s helpful to talk things through methodically with a neutral third party.