Matt Hart

“Cribsheet: A Data-Driven Guide to Better, More Relaxed Parenting, from Birth to Preschool" by Emily Oster

Hardcover, 322 pages
Published 2019 by Penguin Press
ISBN-10 : 0525559256 (ISBN-13 : 978-0525559252)

Finished On: March 5, 2021
How strongly I recommend it: 8/10
Find it at BookShop.org or Amazon

A wonderful guide through the biggest parenting decisions.

My Notes:

We all want to be good parents. We want our choices to be the right ones. So, after we make the choices, there is a temptation to decide the are  the perfect ones. Psychology has a name for this: avoiding cognitive dissonance. pg xxii

So a bath isn't a terrible thing, but there is also really no reason to bathe your kid other than some gross-out factor. Most of the blood can just kind of be wiped off. pg 8

Circumcision is an optional procedure. It's not common everywhere—for example, Europeans typically do not circumcise. It has historically been quite common in the US, although circumcision rates have declined some over time, from an estimated 65 percent of births in 1979 to 58 percent in 2010. pg 9

The American Academy of Pediatrics suggests the health benefits of circumcision outweigh the costs, but they note correctly that both benefits and costs are quite small. The decision will often come down to personal preference, some type of cultural linkage, or just a desire to have your son's penis look a particular way. pg 11

This paper also identified the mechanism: swaddling improves sleep because it limits arousal. pg 30

Infants who are put to sleep on their stomach and are swaddled are at an increased risk of SIDS relative to those put to sleep on their stomach alone. But the crucial thing to avoid is putting your baby to sleep on their stomach, not swaddling. But you basically cannot defeat a crying baby with hard work. There may be some things that improve this in the moment, but babies cray—some of them cry a lot—and there is often really nothing you can do. pg 33

Babies who cry a lot are often described as "colicky." Infantile colic isn't a biological diagnosis like strep throat, but a label we give to babies who cry a lot for no identifiable reason. A common definition of colic (although not the only one) is the rule of three: unexplained crying for more than three hours a day for more than three days a week for more than three weeks. pg 33

Infant crying links to postpartum depression and anxiety, and parents—both parents—will need a break. Try to find one, even if it means leaving the infant crying in their crib for a few minutes while you shower. They will be fine. pg 34

.. there is a commonly accepted rule: no sex until six weeks postpartum, after you have had a checkup with your doctor. This is so often cited that I had assumed it was evidence based, that there was some biological reason why you need to wait this long, no more, no less.

In fact, this is completely fabricated. There is no set waiting period for resuming sex after giving birth. The six-week rule appears to have been invented by doctors so husbands wouldn't ask for sex. pg 50

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. pg 51

A final note: Sex after childbirth can be painful. Breastfeeding promotes vaginal dryness and lowers your sex drive. In addition, injuries during birth can have persistent effects. Many women, after having a small person attached to them nearly constantly, really do not want to be touched. pg 51

Many women experience continued pain and discomfort during sex after giving birth. This is not something you should ignore or grit your teeth and learn to live with. There are treatments that can help, including physical therapy. If sex is painful, talk to your doctor about it. pg 51

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 with experience it. pg 52-53

But women with postpartum anxiety also tend to find themselves fixated on terrible things that could happen to the baby, unable to sleep even if the opportunity is there, and engaging in obsessive-compulsive behaviors around infant safety. This can be treated with therapy or, in more severe cases, with medication. pg 56

The study found two significant impacts: In the first year, breastfed babies had fewer gastrointestinal infections (i.e., diarrhea) and lower rates of eczema and other rashes. To put some numbers to it, 13 percent of the children of mothers in the group that wasn't encouraged to breastfeed had at least one diarrhea episode, versus only 9 percent of those whose mothers were encouraged.  pg 75

SIDS is rare; ear infections and colds are common. Your kids will get colds for sure, whether you breastfeed or not. SIDS deaths, in contrast, occur in about 1 of every 1,800 births; among babies with no other risk factors (not premature, not sleeping on their stomachs), this is perhaps 1 in 10,000. pg 77

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. pg 85

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. [for women who breastfeed] pg 85

Putting them together, breastfeeding initiation and success seem to be higher with skin-to-skin contact, including after a caesarean section. pg 91

Many infants struggle to latch on correctly. Without a good latch, the baby will not get enough milk, and it can be extremely painful for Mom. pg 92

For many women, breastfeeding will hurt for the first couple of weeks whether the baby is latched well or not, so you cannot reliably use pain as a signal. pg 93

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. pg 95

Despite warnings, there is simply no evidence that the use of pacifiers impacts breastfeeding success. This has been shown by more than one randomized trial, including trials that start infants on a pacifier at birth. pg 96

Despite a basically reasonable evolutionary design, this doesn't always work quite as planned. First, it can take a lot of time for your milk to start flowing. Second, even once there is milk, you can have an under-supply. And third, on the opposite end, you can have an oversupply. pg 99

Smoking during pregnancy slows down milk production, as does obesity. Women who have a caesarean section are more likely to have later onset, as are those who have an epidural during labor. pg 100

You can also search for virtually any drug in the LactMed database online. pg 105.  [what drugs are transferred to baby during breastfeeding]

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. pg 106

Your job is supposed to provide breaks for pumping, but they may not always follow the rules. pg 108

It is possible to work while pumping—in some cases—and I strongly suggest you get a hands-free pumping bra. pg 108

Even a really great pump doesn't replicate the baby. This varies across women—some women can have no problem fully breastfeeding but literally never get any milk from a pump; others find producing enough milk is no problem. pg 108

On milk supply:

- The majority of women will have their milk come in within three days after the baby's birth, but for about a quarter, it will take longer.

- The biological feedback loop is compelling: nursing more should produce more supply.

- Evidence on the effectiveness of non-drug remedies (e.g., fenugreek) on supply is limited.  pg 110

The latest recommendations from the American Academy of Pediatrics are starkly opposed to the toy-and-blanket-filled crib. 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. pg 112

When Finn was born, we had him in our room for a few weeks; Jesse slept on an air mattress in the unfinished attic. This did not feel like a long-term plan. pg 112

Excluding birth defects, SIDS is the most common cause of death for full-term infants in the first year of life in the US. By definition, SIDS is the unexplained death of a seemingly healthy infant under a year old, and 90 percent of these deaths occur in the first four months of life. pg 113

One note: If your infant does roll over, there is no need to go rolling them bac. Once they can do this on their own, they highest risk of SIDS has also passed, probably because the baby now has enough head strength to move their head to breathe more easily. pg 117

In the US, the overall infant mortality rate is around 5 deaths per 1,000 births. pg 120

Notably, there does not seem to be any elevated risk from co-sleeping after three months if both parents are not drinking or smoking. pg 120

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. pg 121

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. pg 122

: 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. pg 123

The final AAP guideline for sleep is that (aside from the baby) your child's crib should be empty, with no toys, no bumpers, no blankets or pillows. Nothing. pg 124

The Bottom Line:

- There are some broad guidelines for sleep schedules.

- 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. pg 134

Vaccinations are among the most significant public health triumphs of the past hundred years (public sanitation is another good one, although less controversial). Simply put, millions of lives worldwide have been saved by the introduction of vaccines for disease like whooping cough, measles, smallpox, and polio. pg 135

Andrew Wakefield [fraudulent paper on vaccines that caused a public scare] pg 138

At the end of the day, there is simply no reason to think autism and vaccinations are linked. pg 144

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. pg 147

The Bottom Line:

- Vaccinations are safe.

- A very small share of people have allergic reactions, which are treatable.

- There are some extremely rare adverse events, most of which occur in immune-compromised children.

- The only more common risks are fever and febrile seizures, which are also rare and do not do long-term harm.

- There is no evidence of a link between vaccines and autism, and much evidence to refute such a link.

- Vaccines prevent children from getting sick.

By comparing the outcomes of children who are born in the "six months" maternity leave policy to those born in the "year" policy, we can learn about the effects of maternity leave without worrying about underlying differences across parents.

The bottom line from this literature is that these parental-leaves extensions have no effect on child outcomes. No effects on children's test scores in school, on income later in life, or on anything else.  pg 152

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. pg 152

The United States has subpar maternity leave policies. Many European countries give months—even a year or two—of paid, or partially paid, leave with guaranteed job security. Many people in the US have no paid leave at all, and even unpaid leave (say, through the Family Medical Leave Act, or FMLA) is typically capped at twelve weeks and is available to only about 60 percent of working people. pg 154

Childcare is expensive, and most of it is paid in "after-taxes" income. This means that your income needs to be considerably more than the cost of childcare to break even. pg 155

The data suggests that—putting aside early maternity leave, which has some significant benefits—there is not much evidence that having a stay-at-home parent positively or negatively affects child development.

This means it really comes down to what works for your family. pg 157

Parents in Sweden get a lot of parental leave, but in addition, once they go back to work, there are a variety of excellent government-provided childcare options. pg 159

The researchers doing this study followed the children through sixth grade and continued to find that day-care quality is associated with better vocabulary outcomes, but not with behavior. pg 162

It is true that quality and price are correlated: more expensive day cares are going to be, on average, higher quality. But the main component of quality—how the care provider interacts with the children—is not about price. pg 165

One of the questions—for example—is whether the child has at least three books. But this is a feature of the family, not the nanny. pg 165

Hiring a nanny is a bit of a leap of faith, and you may have to trust your gut. pg 166

Day care is associated with better cognitive outcomes and slightly worse behavior. pg 167

Having books in your house and reading them to your kid is going to matter much more than what books they have at day care. This seems to be true even though your child probably spends as many waking hours with their care providers as with you. pg 168

Your relationship with an in-home caregiver can be complex. If you have a nanny, one day your child will call you by their name. Will this make you feel bad? There is no uniform answers to this, but it is something to think about in advance. pg 169

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. pg 176

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. pg 177

"Cry it out" works, helps parents and kids sleep better, and improves parental mood and happiness. pg 177

This particular study found that, in fact, infant security and attachment seemed to increase after the "cry it out" intervention. It also found improvements in daytime behavior and eating as reported by the babies' parents. Note that this is the opposite of the concerns raised about "cry it out" methods. pg 178

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. pg 178

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. pg 182

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. pg 182

There is relatively little guidance on the appropriate age to start sleep training. Most studies focus on children in the four- to fifteen-month-old period, although these studies tend to recruit people with babies who have been diagnosed with sleep problems, so they are going to be, on average, older. pg 182

The goal of sleep training a ten-week-old baby is to encourage the baby to fall asleep on their own at the start of the night and then only wake when they are hungry later in the night. pg 183

The Bottom Line:

- "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. pg 187

- 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. pg 187

The AAP recommendations echo the traditional Western way to introduce your children to food. This begins, between four and six months, with either rice cereal or oatmeal. You feed your child with a spoon.

Then, a few days or a week later, you introduce fruits and vegetables, one variety at a time, every three days. The standard advice is to do veggies first so kids d not learn fruit tastes better. A month or so after that, you introduce meat. All of this is in a pureed form and fed to your baby with a spoon.  pg 191

For example, there is no evidence for the order of food introductions. If you'd like to start with carrots or prunes rather than rice cereal, I can find no reason in the published evidence not to. pg 192

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. pg 192

An alternative, which has grown in popularity in recent years, is referred to as "baby 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. pg 193

Related to this, 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. pg 196

Before getting into these, and how you might fix them (hard), you should know that most kids become more picky around two and then slowly grow out of it in their elementary school years. pg 197

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!" pg 198

These studies also show that food refusals are more common in families where parents offer alternatives. pg 198

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.  pg 198

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. pg 200

People spend a lot of time telling you how perfect breast milk is, how it's the most amazing food on the planet and contains everything your baby needs! Then, in pretty much the next breath, they hand you a bottle of vitamin D drops and tell you that, actually, breast milk doesn't have enough vitamin D and you'd better remember to give your kid these drops every day, or they might get rickets. pg 201

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. pg 202

This could be as much as a quarter or more of white children, and higher among children of color (darker skin lowers vitamin D absorption from the sun). Deficiency here is defined as having a blood concentration of vitamin D below some cutoff level. pg 202

The Bottom Line:

- 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. pg 203

Cerebral palsy isn't a disease—like a virus or cancer—or a genetic defect.  It's a term to describe motor issues that result from nervous system injury. pg 211

There is simply nothing in the data that would make us think that earlier walking or standing or rolling or head raising is associated with any later outcomes. Looking for delays is a good idea; looking for exceptionalism, or worrying about a child who is at the end of the normal range, is probably not. pg 214

Kids younger than school age get an average of six to eight colds a year, most of them between September and April. This works out to about one a month. pg 215

[Book Reference]: The Portable Pediatrician for Parents by Laura Nathanson.

One thing that has changed since we were children: antibiotics. It used to be common to prescribe antibiotics for cold symptoms, at least some of the time. Not anymore. pg 215

The American Academy of Pediatrics falls squarely in agreement with the second ... 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. pg 218

The study's authors noted that the most significant predictor of both how many words the children spoke and how fast their vocabularies grew was whether their parents read them books. pg 220

Baby Einstein does not seem to live up to the name. This is not the way to bring your kid to the head of their day-care class. Of course, if you—gasp!—would like to use these videos to distract your kid while you, say, take a shower, vocabulary development may not be the goal. (More on the question of detrimental effects below.) pg 220

All this is to say that for slightly older children, television can be a source of some learning; this argues (among other things) for curation of what they watch. For very young children, what they watch may actually matter less, since they do not learn much from it, although you cannot rely on the TV to make your child a genius. pg 221

1. Children under two years old cannot learn much from TV.

2. Children ages three to five can learn from TV, including vocabulary and so on from programs like Sesame Street.

3. The best evidence suggests that TV watching in particular, even exposure at very young ages, does not affect test scores.

In the field of statistics, there are at least two broad approaches. The first is "frequent statistics," which approaches learning about relationships in data using only the data we have. The second is "Bayesian statistics," which tries to learn about relationships by starting with a prior belief about the truth, and using data to update it. pg 225

A Bayesian approach is to think about how to incorporate other things you know—or think you know—about the world into your conclusion along with the data. pg 225

The Bottom Line:

- Your zero- to two-year-old cannot learn from TV.

- A three- to five-year-old can learn from TV.  (t is worth paying attention to what they are watching)

- The evidence is sparse overall. When in doubt, use your "Bayesian priors" to complement the data. pg 227

At the two-year-old doctor visit, it is common to be asked whether the child has at least twenty-five words they say regularly. At fewer than this, it may be appropriate to bring in some outside help to figure out what is wrong. pg 230

At twenty-four months, for example, the average girl has about fifty more words than the average boy. By thirty months, the most advanced boys and girls are similar, but there are still large differences at other points in the distribution. pg 234

The Bottom Line

- There are some standard tools to determine child vocabulary size, which you can use on your own. There are also some metrics you can compare.

- Girls develop language faster than boys, on average, although there is a lot of overlap across genders.

- The timing of language development does have some link with later outcomes—test scores, reading—but the predictive power is weak for any individual child. pg 237

The main and probably only benefit to potty training a child earlier is that you do not have to change as many diapers. The main reason to wait is that the earlier you start, the longer it takes to complete. We can see this in the same data described above, with the 400 children starting at 18 months. pg 241

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. pg 243

There is no evidence linking age of potty training with any later outcomes like IQ or education. pg 246

Staying dry at night —or effectively waking up to use the bathroom—is a skill fundamentally different from using the toilet during the day. Many children will remain in a pull-up or diaper at night (and maybe when napping) long after they are fully trained during the day. pg 248

By the age of five, 80 or 85 percent of children are dry at night (meaning not that they do not pee, but that if they do, they wake to use the bathroom).

Doctors generally don't worry about a lack of nighttime dryness until a child is six years old. pg 248

Toddler discipline is, really, parental discipline. Breathe. Take a second. I once told my children, "I'm so mad right now, I'm going to the bathroom for a while to calm down."

The Bottom Line

- There are a variety of programs that have been shown to improve children's behavior. These focus on consistent rewards and punishments, and avoiding parental anger. (Examples include 1-2-3 Magic and the Incredible Years, among others.

- Spanking has not been shown to improve behavior and, indeed, has been associated with worse behavior in the short term and even through adulthood. pg 258

What the research found was that children who were read to more at home showed more brain activation in the areas of the brain thought to be responsible for narrative procession and imagery. pg 262

In particular, researchers have found that the benefits are bigger with more interactive reading. Rather than just reading a book, kids benefit from being asked open-ended questions:

"Where do you think the bird's mother is?"

"Do you think it hurts Pop when the kids hop on him?"

"How do you think the Cat in the Hat is feeling now?"

If you are inclined to teach your four-year-old to read, you can probably make some progress. There is a separate question of whether you want to, but that is more a parenting choice than a question for the data. pg 263

It should be said that some cases of this prodigious early reading are associated with autism. Hyperlexia (as it is called) is a trait of some high functioning autistic children; children can read but do not understand. pg 264

The evidence I discussed there showed that more time in day care after eighteen months or so was associated with better language and literacy development at slightly later ages. This is about the best evidence we have that preschool might be a good idea. pg 265

... I'd say the weight of the evidence is that some preschool environment around age two or three will, on average, improve the ease with which they transition to school. pg 265

Indeed, the non-Montessori approaches often emphasize the importance of play and argue that early literacy is not an important outcome. pg 267

There are a couple of non-randomized studies from outside the US showing that children who learn to read later do catch up in terms of reading within a few years and that teaching the alphabet early doesn't necessarily impact reading. But on the other hand, we know that programs like Head Start, which focus on early literacy, do improve school performance early on. pg 267-268

In fact, the effects go both ways. Some studies suggest that if men do more chores, the couple has less sex. Some suggest the opposite—that the couple has more sex. pg 277

Since these biases go in both directions, it's virtually impossible to learn anything.

It maybe go good to get your spouse to do the dishes, but the value of that is that the dishes get done, not that you're going to be inspired to start ripping their clothes off in a haze of soap suds and flying plates. pg 278

Although it is not a solution, it is worth noting that couples who are happier in their marriage before kids and who planned their pregnancies tend to have smaller declines and faster rebounds in their happiness. pg 278

So waiting until the first child is at least a year old to get pregnant again may be a good idea. It also just may be easier on you as a parent, given the intensity of the infant stage.

The Bottom Line:
- The data doesn't provide much guidance about the ideal number of children or birth interval between them.
- There may be some risks to very short intervals, including preterm birth and (possibly) higher rates of autism.

But there is a flip side. Little kids mean mostly little problems. As your kid gets bigger, the number of things you worry about goes down, but they get more important.

At the end, let's raise a glass to using data where it's useful, to making the right decisions for our families, to doing our best, and—sometimes—to just trying not to think about it.