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

by Emily Oster

One of the benefits of skin-to-skin contact seems to be increased breastfeeding success. Perhaps for this reason, breastfeeding success also seems to be increased by delaying the bath past the first few hours.

In my view, the most important thing to come out of this is, if you have the option to send your kid to the nursery for a few hours and you want to do that, you shouldn’t feel shame in doing so. There is no good evidence that you’re disrupting your breastfeeding relationship, if that’s important to you. And if you find yourself falling asleep with your baby in the bed, ask for help.

The authors of this paper created a website, www.newbornweight.org, where you can enter the time of birth of your child, method of birth, method of feeding, birth weight, and current weight and learn where they are in the distribution.

But to the extent that we know anything, we know there’s no reason to think a short period of supplementing with formula should impact breastfeeding success (if that is your goal) in the long run.

If your baby is peeing with some frequency and does not have a dry tongue, there’s a very good chance he’s not dehydrated. Conversely, if you see these signs, supplementation may be a good idea, even if there isn’t too much weight loss.

there is also a website that will tell you if jaundice treatment is recommended given bilirubin levels: www.bilitool.org. It’s for doctors, but it’s accessible to anyone who is curious.

We used one called the Miracle Blanket.

The study strongly supported the value of swaddling for sleep. While swaddled, the babies slept longer overall, with more time spent in REM sleep. This paper also identified the mechanism: swaddling improves sleep because it limits arousals.

Two treatments have some known success with colic. One is supplementation with a probiotic, which a number of studies have shown to reduce crying. These effects seem to show up only in breastfed infants.9 This treatment isn’t complicated—probiotics are delivered in drops, and Gerber and others make easily accessible over-the-counter versions. With no recognized downsides, probiotics are certainly worth a try.

The other treatment that has shown some success is managing the baby’s diet, either by changing formula types or, if the baby is breastfed, changing the mother’s diet.

complicated, since it means changing your own. There is some evidence supporting a “low-allergen” diet for Mom: randomized studies have shown reductions in crying and infant distress when mothers adopt this type of diet.11 The standard recommendation is the elimination of all dairy, wheat, eggs, and nuts, so this means a pretty dramatic dietary change.

There is a broad theory called the hygiene hypothesis, which states (I am paraphrasing here) that the increase in occurrences of allergies and other autoimmune illnesses over time is a result of decreased germ exposure in childhood, and that exposure to more microbes and germs as a child can help their immune system properly identify and not overreact to perceived pathogens.13 While we don’t have conclusive proof that this is true, there is some evidence backing the theory in the form of laboratory studies of particular cells and comparisons across cultures in rates of various diseases.

try to avoid exposure to illness in the baby’s first couple of months. One reason for this is simply that the smaller the child, the more vulnerable they are to serious complications. But a second reason is that for very young infants—especially those younger than twenty-eight days—medical protocols suggest much more aggressive interventions in response to illness.

The big downside of being exposed to germs—or specifically, to sick kids—during these early weeks is the possibility of setting off this chain of interventions. If your infant does get sick, these procedures make sense, but if they just caught a cold from being pawed by a germy two-year-old, you’ll be doing a lot of interventions for no reason. It’s therefore better to keep the germy two-year-old away from the newborn, if at all possible. Once your baby is over three months, and especially after they’ve had the first set of vaccines, treatment of a fever is closer to what you’d expect with an older child—basically, give them some Tylenol, keep them hydrated, and wait for it to go away. At this point, the downside of germ exposure is simply a sick kid, not a cascade of invasive testing.

and improve sleep. It is important to swaddle in a way that allows the baby to move its legs and hips. Colic is defined as excessive crying. It is self-limiting, meaning it will stop eventually. Changing formula or maternal diet, treatment with a probiotic, or both have shown some positive impacts. Collecting data on your baby is fun! But not necessary or especially useful. Exposing your infant to germs early on risks their getting sick, and the interventions for a feverish infant are aggressive and typically include a spinal tap. Limiting germ exposure may be a good idea, even if just to avoid these interventions.

Most tears are on the minor side, but approximately 1 to 5 percent of women will have more serious third- and fourth-degree tears.1 More severe tearing is more common with instrument-assisted delivery (that is, delivery with either forceps or a vacuum). There is some evidence that warm compresses on the perineum during the pushing stage of labor can prevent very severe tears.

First of all, you’ll still look pregnant. This appearance will subsist for a few days or weeks. Then you’ll just have a bunch of floppy skin. This does resolve eventually (by which I mean weeks or months later, not days), but it’s a little disconcerting to look down at. Even once the floppy skin is gone, many of us find we have what is referred to as “mummy tummy,” a pouchy stomach that doesn’t ever seem to quite snap back. I can find no literature on this, but I assure you it is a real thing that no amount of Pilates can get rid of (and by “no amount” I specifically mean one hour a week with Larry, whose other clients are mostly elderly women).

They caution, though, that this will be different if you’ve had a caesarean or significant vaginal tearing. In the case of a caesarean, the standard recommendations include some walking within the first two weeks, introducing the possibility of abdominal curls or other related exercises by week 3 and a resumption of “normal” activities by around week 6.3 Again, healing rates differ from woman to woman, so this is really just an average.

Looking at the data—which, in this case, may not be so helpful, since really the question is when you want to do it—most couples have resumed at least some sexual activity by eight weeks postpartum. For those with an uncomplicated vaginal delivery, the average is about five weeks, versus six weeks for caesarean and seven for those with significant vaginal tearing.

The prevalence of postpartum depression, even if we focus only on diagnosed cases, is high. An estimated 10 to 15 percent of women who give birth will experience it.

Where does this leave us? Certainly, it seems reasonable to conclude that breastfeeding lowers infant eczema and gastrointestinal infections. For the other illness outcomes, the most compelling evidence is in favor of a small reduction in ear infections in breastfed children.

There is one benefit that does have a larger and more robust evidence base: the link between breastfeeding and cancers, in particular breast cancer. Across a wide variety of studies and locations, there seems to be a relationship here, and a sizable one—perhaps a 20 to 30 percent reduction in the risk of breast cancer. Breast cancer is a common cancer—almost 1 in 8 women will have a form of it at some point in their lives—so this reduction is big in absolute terms. This data isn’t perfect—for one thing, the controls for maternal socioeconomic status are almost always missing—but the case for causality is bolstered by a concrete set of mechanisms. Breastfeeding changes some aspects of the cells of the breast, which makes them less susceptible to carcinogens. In addition, breastfeeding lowers estrogen production, which in turn can lower the risk of breast cancer.

First, there is some randomized evidence on the success of skin-to-skin contact at improving breastfeeding success rates. Skin-to-skin contact is the practice of having women hold their naked (or diapered) baby against their naked chest, typically right after birth. The idea is that the smells and the proximity will encourage the baby to start feeding immediately.

For most women, even those whose babies latch well, breastfeeding is at least somewhat painful early on. Any pain should be mostly gone after the first minute or two of nursing, not continue. Certain conditions can cause ongoing pain—for example, nipple yeast infections—but are treatable. It would be a shame not to figure that out, so if your pain persists, ask for help.

Despite the warnings, there is simply no evidence that the use of pacifiers impacts breastfeeding success.

Based on this comparison, the authors argued that babies who sleep on their stomachs are eight times as likely to die of SIDS. This paper also cited overheating as a risk factor—the babies who died were more likely to be wearing heavy clothing to bed, sleeping under a lot of bedding, or sleeping in a hot room.

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.

if neither parent smokes or drinks a lot, and if the baby is breastfed? The data here says yes. The risk of death for infants who do not bed share in the lowest risk group is 0.08 SIDS deaths per 1,000 births. For those who bed share, it is 0.22 deaths per 1,000 births. Again, we want to put these risks into a broader context. In the US, the overall infant mortality rate is around 5 deaths per 1,000 births. This therefore represents a very small increase relative to the overall mortality rate. A perhaps more useful way to say this is that among families with no other risk factors, roughly 7,100 of them would have to avoid co-sleeping to prevent one death.

Notably, there does not seem to be any elevated risk from co-sleeping after three months if both parents are not drinking or smoking.

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

believe the AAP recommendations go too far. If you want to share a room with your child, by all means do. And perhaps—perhaps—the data warrants a mild recommendation in favor of very early room sharing. But to tell people they need to keep their child in their room for a year, sacrificing both short- and long-term sleep success with no clear benefit in the process, may not be a good policy.

Looking back at the results above, it seems clear, first, that having your child sleep on their back and avoiding blankets and pillows and other soft items in the crib are good ideas. Avoiding sofa sleeping is also strongly recommended. These recommendations have the most compelling evidence, and are also the easiest to implement. It also seems clear that smoking raises the risk of SIDS, especially if you choose to bed share. Finally, looking at the data, we have to conclude that in terms of SIDS risk, choices about sleep location—in your bed, in your room—matter much more in the first four months of your baby’s life.

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.

Babies benefit from their mothers taking some maternity leave. However, there is little evidence suggesting that having a stay-at-home parent after the parental leave period has either good or bad consequences for children. Decisions about whether to have a parent stay home should consider your preferences, along with consequences for your family budget in both the short and long term. Stop judging people!

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

Studies that combine this suggest that, overall, the effect is positive—that kids who are in day care for more time over this entire period have better language and cognitive outcomes at four and a half.4 On the behavior side, there are small associations between behavior problems and more time in day care at all ages, although the authors caution that these effects are fairly minimal and all the children were in the “normal” behavior range.

Putting this together could argue for a nanny-type arrangement (or a helpful grandparent, or some combination of the two) early on, followed by day care at a slightly older age.

On average, more time in day-care centers seems to be associated with slightly better cognitive outcomes and slightly worse behavior outcomes. The positive effects of day care present more at older ages, the negative ones more at younger ages. Kids in day care get sick more, but develop more immunity.

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.

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.

there. They returned to evaluate the children a year later and, most notable, five years later, when the children were almost six. In this later follow-up, which included a subset of the original families, the researchers found no difference in any outcomes, including emotional stability and conduct behavior, stress, parent-child closeness, conflict, parent-child attachment, or attachment in general. Basically, the kids who were sleep trained looked exactly like those who were not.

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.

“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.

Parents of children in the exposure group were told to expose their kids to a dose of peanuts—about 6 grams a week—in the form of either the Israeli snack Bamba or regular peanut butter.

Children who were exposed to peanuts were far less likely to be allergic to them at the age of five than children who were not. In the group that didn’t get peanuts, 17 percent of children were allergic to peanuts at age five. (Remember, this figure is higher than it would be in the general population because of the way the researchers selected their sample.) However, only 3 percent of the children who were given peanuts were allergic.

The primary finding relates to how parents talk about the new food. 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!!”

Putting this together leads to some general advice: offer your very young child a wide variety of foods, and keep offering them even if the child rejects them at first. As they get a little older, do not freak out if they don’t eat as much as you expect, and keep offering them new and varied foods. If they won’t eat the new foods, don’t replace the foods with something else that they do like or will eat. And don’t use threats or rewards to coerce them to eat.

On the first question, the answer is probably yes. The vast majority of allergies result from eight food types: milk, peanuts, eggs, soy, wheat, tree nuts, fish, and shellfish.

Early exposure to allergens reduces incidences of food allergies. Kids take time to get used to new flavors, so it is valuable to keep trying a food even if they reject it at first, and early exposure to varying flavors increases acceptance. There is not much evidence behind the traditional food-introduction recommendations; no need to do rice cereal first if you do not want to. Baby-led weaning doesn’t have magical properties (at least not based on what we know now), but there is also no reason not to do it if you want to. Vitamin D supplementation is reasonable, but don’t freak out about missing a day here and there.