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

by Emily Oster

The Bottom Line Newborn baths early on are unnecessary, but not damaging. Tub baths are better than sponge baths. Circumcision has some small benefits and also carries some small risks. The choice is likely to come down largely to preference. Rooming in doesn’t have any compelling effects on breastfeeding outcomes either way. It is worth being careful about falling asleep with your infant if you choose to keep them with you at all times. Infant weight loss should be monitored and compared with expectations; you can do this yourself at www.newbornweight.org. Jaundice is monitored with a blood test and should be treated if outside the normal range; you can monitor this yourself at www.bilitool.org. Delayed cord clamping is likely recommended, especially if your baby is premature. Vitamin K supplements are a good idea. Eye antibiotics are likely unnecessary for most babies but are mandated in some states and have no known downsides.

The Bottom Line Swaddling has been shown to reduce crying 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.

Less common but much more severe is postpartum psychosis.7 This affects an estimated 1 to 2 in 1,000 women (versus 1 in 10 for postpartum depression) and is much more likely to develop in women with a history of bipolar disorder. Postpartum psychosis usually manifests in hallucinations, delusions, and manic episodes. It will very likely need inpatient treatment, and should be taken extremely seriously.

The Bottom Line It takes time to recover from childbirth. You’ll bleed for several weeks. You may have vaginal tearing, which takes a few weeks to heal. A caesarean section is major abdominal surgery, and it will take significant time for you to be mobile again afterward. Return to exercise depends a bit on your birth experience, but you can typically start within a week or two, and most women could be back to their pre-pregnancy routine by six weeks. There is no set waiting time for sex, although you should wait until you’re ready (and are on birth control if you’re not ready for another child). Postpartum depression (and related conditions) are common and treatable. Get help as soon as you need it.

The Bottom Line There are some health benefits to breastfeeding early on, although the evidence supporting them is more limited than is commonly stated. There are likely some long-term health benefits, related to breast cancer, for Mom. The data does not provide strong evidence for long-term health or cognitive benefits of breastfeeding for your child.

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

The Bottom Line Breastfeeding can be very hard! On early interventions: Skin-to-skin contact early on can improve likelihood of breastfeeding success. On latching: Nipple shields work for some women, although they can be hard to quit. There is very limited evidence that fixing a tongue tie or lip tie can improve nursing. On pain: Fixing a tongue tie can improve pain for Mom. There isn’t much evidence on how to fix nipple pain, but focusing on the latch may help. If you are still in pain a few minutes into a feeding, or a few weeks into nursing, get help; it could be an infection, which would be treatable, or some other problem with a solution. On nipple confusion: Not supported in the data. 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. On pumping: It sucks.

The finding that co-sleeping carries a small risk even if done as safely as possible is largely consistent across studies, and although the exact size of the increased risk varies from report to report, they are in a similar range.16 These risks are concentrated early in life. 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 Bottom Line There is good evidence that infants who sleep on their back are at lower risk for SIDS. There is moderate evidence that bed sharing is risky. These risks are much higher if you or your partner smokes or drinks alcohol. There is some less-good evidence that room sharing is beneficial. The benefits to room sharing die out in the first few months. Infant and child sleep may be better if your child sleeps alone after the first few months. In the crib: Wearable blanket: check! Bumpers: very small risk, although small benefits as well. Sleeping on a sofa with an infant is extremely dangerous.

The Bottom Line 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 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.

The Bottom Line 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 Bottom Line With any childcare arrangement, quality matters. For day care, in particular, you can use some simple tools to try to do your own quality evaluation. 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. Parenting quality swamps childcare choices in its importance, so make sure you pick something that works for you as a parent as well.

Sleep-training methods consistently improve parental mental health; this includes less depression, higher marital satisfaction, and lower parenting stress.

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.”

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. 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.

If you do want to try baby-led weaning, there is nothing in the evidence to say it is a bad idea. If you do not, there is also nothing compelling to say you should go out and do it.

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.

The vast majority of allergies result from eight food types: milk, peanuts, eggs, soy, wheat, tree nuts, fish, and shellfish.

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.

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.

Based on what is available, I’d say we can learn a few things: Children under two years old cannot learn much from TV. Children ages three to five can learn from TV, including vocabulary and so on from programs like Sesame Street. The best evidence suggests that TV watching in particular, even exposure at very young ages, does not affect test scores.

The Bottom Line Your zero- to two-year-old cannot learn from TV. A three- to five-year-old can learn from TV. It 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.

The Bottom Line Age at toilet training has increased over time, very likely as a result of parents choosing to train later. Starting training earlier leads to earlier completion on average, although it generally takes longer; starting intensive training before twenty-seven months does not seem to lead to earlier completion. There is little evidence on the efficacy of child-led training versus more intensive, goal-oriented methods. Refusal to poop on the toilet is a common complication with some limited solutions.

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.

The Bottom Line There is some support for the value of reading to your children starting in infancy. Your baby cannot learn to read. Whether your two- or three-year-old can is unclear, but it would be very unusual for them to be a fluent reader. Evidence on the value of different preschool philosophies is limited.

Marital satisfaction does decline, on average, after children. These declines are smaller and briefer if you’re happier before children, and if the kids are planned. Unequal division of labor and less sex probably do play some role, although it is hard to get a sense of how important these are. There is some small-scale evidence suggesting marital counseling and “marriage checkup” programs can improve happiness.