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

by Emily Oster

A final note is on caffeine. Most people find it’s fine to have caffeine while nursing, and there is certainly no literature suggesting risks to the baby. However, some babies are quite sensitive to caffeine and get very fussy and irritable. If you find this is the case, you may have to avoid it.

One doctor I spoke to said she pumped in the coed locker room, in full view of everyone (she used a towel to cover). Companies over a certain size are required to provide lactation rooms, but this isn’t always followed, and there is no requirement that the rooms be nice.

Even in a perfect situation, you’re supposed to wash the pump parts after every usage, and it just takes time. (Pumping wipes can help with this part.) If you pump for thirty minutes three times a day—not unusual at all—these are ninety minutes you could be doing something else.

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.

In at least some cases here, the risks are clear and not vanishingly small; in those cases, the choice is easy. In others, it seems clear the risks are really not there at all. But in some of these cases—co-sleeping, in particular—more complex considerations come into play, and we’ll need to confront them.

The medical recommendations to avoid SIDS have four components. Infants should be (1) on their back, (2) alone in the crib, (3) in their parents’ room, and (4) with nothing soft around.

This effort came in the form of the aforementioned “Back to Sleep” campaign, which began in the US in 1992, and was remarkably successful. In surveys done in 1992, researchers found that around 70 percent of babies were put to sleep on their stomach.9 By 1996, this figure was only 20 percent. This large change in sleeping position was also accompanied by a decrease in the SIDS rate, further suggesting that sleep position plays a role in SIDS.

One note: If your infant does roll over, there is no need to go rolling them back. Once they can do this on their own, the highest risk of SIDS has also passed, probably because the baby now has enough head strength to move their head to breathe more easily.

The American Academy of Pediatrics recommends that infants be in their parents’ room through at least the first six months, and ideally the first year, of life as a guard against SIDS. The theory is that parents can be more attentive to the baby if they are in the same room. The evidence on room sharing and SIDS is substantially less complete than the evidence on bed sharing.

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 This means there is seemingly no benefit to extending room sharing for so long. There is, however, a real cost: child sleep. In a 2017 study, researchers evaluated whether a child’s sleeping in a room with a parent made for worse sleep. They found that it did. At four months old, total sleep time was similar for babies sleeping in a parents’ room and those sleeping in their own room, but sleep was more consolidated (i.e., in longer stretches) for those in the latter group. This makes sense: their own room will be quieter.

At nine months, infants who slept alone slept longer; this effect was largest for those who slept alone by four months, but also appears for babies who moved to their own room between four and nine months. Most notably, these differences were still present when the child was two and a half years old: children who slept alone by nine months slept forty-five minutes more during the night than those who were room sharing at nine months. Sleep is crucial for child brain development; it is not just a selfish parental indulgence. Of course, this may not be causal—maybe parents move their kids to their own room when they start sleeping well—but it is suggestive.

it should be said that if you plan to sleep train your child, success is very unlikely while the child is sleeping in your room. And finally, most people sleep better without a child in the ro...

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. Death rates as a result of this behavior are twenty to sixty times higher than the baseline risk. It is not difficult to see why: an exhausted adult falls asleep holding an infant on a cushiony sofa, and it is easy for the infant to be smothered by a pillow. The unfortunate thing is that in at least some of these sofa deaths, the parent involved is trying to avoid the risks associated with bed sharing. They hope that if they sit up, they will stay awake, and then they fall asleep by accident. Even with the small risks of bed sharing, you’d be much better off sharing a bed than accidentally co-sleeping on a sofa.

the evidence suggests that bed sharing increases the risk of death by 0.14 per 1,000 births. The death rate from car accidents in the first year of life is around 0.2 per 1,000 live births. The bed-sharing risk is therefore a real one, but it is smaller than some of the risks you are likely taking regularly.

Sleeping on a sofa with an infant is extremely dangerous.

Sleep is important! It’s important for baby development, and for parents. Your child will be in a better mood if they get the right amount of sleep. For a toddler, napping too much may make it harder to get to sleep at night. This means no sleep for parents. If they nap too little, they may be too overtired to get to sleep at night. This also means no sleep for parents. How much sleep is enough, and when should it happen? It seems like a simple question, but answers differ widely.

The books generally note that around six weeks, infants start to sleep longer at night; at three to four months, naps start to consolidate; at around nine months, the third nap disappears; at a year to twenty-one months, the second nap disappears; and at three to four years, the final nap disappears. On these latter two transitions in particular, these ranges are wide. A year to twenty-one months is a long time!

Around two months, there is a big jump up in the average longest sleep period—this is the consolidation of nighttime sleep. This then increases more slowly as the child ages.

Nine to ten months is the point at which the average number of naps is two; at eighteen to twenty-three months, it moves all the way to one.

Take, as an example, the question of nighttime sleep length. In this data, the average six-month-old baby sleeps ten hours a night. Great—that’s about what we saw in the studies I mentioned earlier. What about the baby at the 25th percentile (this would be a baby who didn’t sleep much)? Nine hours. What about the 75th percentile? Eleven hours. Now, what about the whole range of the data for six-month-olds? It turns out, in the data they see babies who sleep as few as six hours at night, and babies who sleep as many as fifteen hours. This makes things a bit clearer: at least part of the reason the books are vague is that there is not really one answer to the question of how much children sleep at night.

In conclusion, many aspects of scheduling will be kid specific, and attempts to organize your baby are likely to meet with some of these variations. But not everything varies. 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.

Some things about a second child are harder, the main one being the presence of the first child. But some things are easier, and at least in my experience, schedule is one of them. Before you have any children, you’re on an adult schedule—wake up for work, eat dinner late, maybe stay up to watch some TV. Catch up on sleep on the weekends. Sometimes, maybe, you go to bed earlier, sometimes later. Once you have even one child, you’re on their schedule. Wake up between six thirty and seven thirty a.m., breakfast, nap, lunch, nap, dinner, bedtime around seven thirty p.m. (ideally). When the second child arrives, they are not on this schedule immediately, of course, but you know where you are going.

The other thing you realize with your second child is that the unscheduled mess of the first year does end. Your baby will, eventually, arrive at a more predictable sleep schedule. Maybe not right away, maybe not exactly the one you envisioned, but they will get there. And this is perhaps the most reassuring thing of all.

In the 1950s, about five hundred people—mostly children—died of measles each year in the US; 3 to 4 million were sickened. In 2016, zero children in the US died of measles, and there were an estimated eighty-six cases.1 There is a very simple reason for this decline: the development of a measles vaccine.

Some vaccine-anxious parents favor a delayed vaccine schedule, in which children receive vaccines spaced out over a longer period of time rather than being given several at once. There is no reason to do this, given the evidence on vaccine safety that I outlined earlier, and in fact, the risk of a febrile seizure actually increases if the MMR vaccine is given later.14 Delaying vaccines will not help to avoid any of the limited adverse events attributed to vaccination. It also takes more of your time to visit the doctor repeatedly for shots, and your kid will not like them.

So let’s start by just framing this not as “What kind of mom will you be?” but “What is the optimal configuration of adult work hours for your household?” Less catchy, yes, but also perhaps more helpful for decision-making.

It isn’t that I like my job more than my kids overall—if I had to pick, the kids would win every time. But the “marginal value” of time with my kids declines fast. In part, this is because kids are exhausting. The first hour with them is amazing, the second less good, and by hour four I’m ready for a glass of wine or, even better, some time with my research.

There is sometimes a bit of nuance in the results. One thing that is commonly seen is that children in families where one parent works part time and the other works full time tend to perform best in school—better than children whose parents both work full time or who have one parent who doesn’t work at all.3 This could be due to the working configuration, but I think it’s more likely due to differences between these families.4

Parental leave appears to be beneficial. There is a growing body of evidence suggesting that babies do better when their mothers take some maternity leave. In the US, for example, research has shown that when the FMLA was introduced, babies did better. Premature birth went down, as did infant mortality.7 The mechanism may be that if moms are off work with small babies, they are better able to get care for them when they are sick. This policy may also have encouraged leave before birth for women with difficult pregnancies, which could account for the effect on premature birth.

Your kids will get less expensive as they grow up. School-age kids tend to cost less—public schools are free, for example. And if you stay in the workforce, your income will probably go up (this depends a bit on your job, but is true for many people). This means that even if working doesn’t seem like a good deal for the first few years, it may be a good deal in the long run.

Second, you want to think about what economists call the “marginal value of money.” Let’s say your family would be better off in terms of income if you worked. You can calculate this in a dollar value, but that doesn’t necessarily tell you how much happier you’d be. You really want to think about how much your family would value that money in terms of what economists call “utility,” aka happiness. How different will your life be? What will you buy with this money? If it doesn’t make you happier, then it isn’t worth much, even if it is money.

Some people love being with their baby every minute and cannot imagine being away. Some people eagerly look forward to returning to work on Monday morning, even if they love their kids just as much. And this may change as the children age. Some people really love babies. I have found that as my kids get older, I enjoy being with them more. I still do not want to be a stay-at-home parent, but I think I’d like it more now than I would have when they were younger. Try to be honest with yourself about what you want. None of this is very helpful to you in making a choice. Sorry! Ultimately, you are on your own.

A final data-driven comparison is with illness. 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.

The question is what would you do if you had that money? What is the next best, non-childcare, use of these funds? This is the same question I encouraged you to ask about having a parent stay home.

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.

On average, more time in day-care centers seems to be associated with slightly better cognitive outcomes and slightly worse behavior outcomes.

Most people are prepared for the first couple of sleepless weeks with a baby; maybe your family is around, or at least you aren’t working off a base of exhaustion. But then month 2 comes, and still the baby is sleeping only two hours at a stretch. At some point, the pediatrician tells you, “A baby of this size can sleep for up to six hours at a time.” You want to poke them in the eye with a pen.

Good news: yes, this method works for improving sleep. There are many, many studies on this, employing a variety of related procedures (many of these are randomized trials). 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. These effects persist through six months or a year in studies that can look this far out. This means that children who are sleep trained are sleeping better (on average) even a year after the training.

babies in the control group got up four nights a week on average, versus only two nights for babies who were sleep trained.4 The sleep-trained babies also woke up less frequently on the nights they did get up.

Not every baby who is sleep trained will sleep through the night every night, but they do sleep better on average. Getting up four nights a week is significantly worse than getting up two nights.

The bottom line is that there is simply a tremendous amount of evidence suggesting that “cry it out” is an effective method of improving sleep.

It is worth noting that most of these studies—and, indeed, virtually all sleep books—recommend a “bedtime routine” as part of any sleep intervention. There isn’t much direct evidence on this—the review refers to it as a “common sense recommendation”—but it is generally included with all intervention approaches. The idea is to have some activities that signal to the baby that it is bedtime: putting on the baby’s pajamas, reading them a book, singing some kind of song, turning off the lights. Basically...

This finding is consistent across studies. Sleep-training methods consistently improve parental mental health; this includes less depression, higher marital satisfaction, and lower parenting stress.6 In some cases the effects are very large. One small (non-randomized) study reported that 70 percent of mothers fit the criteria for clinical depression at study enrollment, and only 10 percent after the intervention.

A 2006 review of sleep-training studies, which included thirteen different interventions, noted the following: “Adverse secondary effects as the result of participating in behaviorally based sleep programs were not identified in any of the studies. On the contrary, infants who participated in sleep interventions were found to be more secure, predictable, less irritable, and to cry and fuss less following treatment.”9 (Translation: Nothing bad happened in any study, and in most cases, the babies seemed happier after sleep training than before.) More recent studies draw the same conclusion.10

Most “cry it out” methods are variants on one of three themes: Extinction—just leave, and do not return; Graduated Extinction—come back at increasingly lengthy intervals; and Extinction with Parental Presence—sit in the room, but do not do anything. Ferber is a proponent of the second, whereas Weissbluth is more in favor of the first. There is evidence that all three methods work—more evidence, perhaps, on the first two than the third—but relatively little evidence on which works best. On the one hand, some reports seem to find that Graduated Extinction is easier for parents and leads to more consistency; other studies have found it prolongs crying.16 The only general principle from these is that consistency is key. Choosing a method—whichever one—and sticking with it increases success. So the most important consideration here is likely what you think you can do. Will knowing you can check on the baby help you feel better? Or would you rather just close the door and leave it closed?

Sleep training should not be something you decide to do on a whim because your baby is being a jerk today. It should be something you plan—ideally with both parents and caregivers, and perhaps also with your doctor. And once you have a plan, stick to it.

After some back and forth, we agreed on the following system. PART 1: BEDTIME/START OF NIGHT Finn will go to bed during Penelope’s bedtime, around 6:45. We will put his pj’s on and read him a book as part of the bedtime routine. He will nurse, and then we’ll put him down in bed. We will not return at all before 10:45 p.m. PART 2: OVERNIGHT SCHEDULE Will feed Finn the first time he cries after 10:45 p.m. After the first feeding, do not respond again until at least 2 hours after the end of each feeding. Example: If he eats from midnight to 12:30 a.m., then do not respond for another feeding until, at the earliest, 2:30 a.m. NOTE: THE LONGEST STRETCH OF SLEEP IS EARLY IN THE NIGHT, SO WEISSBLUTH SAYS WE SHOULD RESPOND MORE FREQUENTLY IN THIS PERIOD THAN AT THE START OF THE NIGHT. PART 3: THE MORNING Wake-up is between 6:30 and 7:30 a.m. If he is awake at 6:30 we get him up. If he is not awake he can sleep until as late as 7:30. At that time we wake him up if he is not up already.

I think part of our success was having a plan written down. You may not want to be quite so formal, and even if you have a plan, there will likely be some deviation from it—that is okay! But knowing at least in rough terms what you are planning, and agreeing with your partner on it, is likely a good idea.

Part of our success with Finn, we know, was simply because he was an easier baby than Penelope. We were also more experienced parents. Even if you treat your kids exactly the same, they may be different. Some will respond better than others.

“Cry it out” methods are effective at encouraging nighttime sleep. There is evidence that using these methods improves outcomes for parents, including less depression and better general mental health. There is no evidence of long- or short-term harm to infants; if anything, there may be some evidence of short-term benefits. There is evidence of success for a wide variety of specific methods, and little to distinguish between them. The most important thing is consistency: choose a method you can stick with, and stick with it.