The week's best parenting advice: September 20, 2022

You probably shouldn't get your child a bulletproof backpack, writes Melinda Wenner Moyer. School shootings are "still very much an anomaly," and when they do occur, it's not clear that bulletproof backpacks would be helpful. "For a bulletproof backpack or insert to save a child's life, that child would need to be wearing it or shielded behind it when the shooting happens, and the bullet would have to strike only the backpack, which is unlikely," Wenner Moyer writes. Plus, while bulletproof backpacks might stop shots from a 9mm pistol or a .45-caliber handgun, they don't seem to stand up to semi-automatic rifles like an AR-15. Most importantly, asking your child to wear a bulletproof backpack sends a clear message that you think they are unsafe at school. And that's a problem, "because when kids persistently feel unsafe, they are more likely to become depressed, anxious, and suicidal," Wenner Moyer writes.

Rates of myopia in the U.S., Asia, and Europe have been rising for decades, without a clear explanation, writes Sarah Zhang in The Atlantic. One theory holds that rising myopia is driven by "'near work,' which might include reading and writing — or, these days, watching TV and scrolling through Instagram." But the research backing this theory is mixed, and some researchers think that near work itself isn't so much the problem as the fact that it "deprives kids of time outdoors," writes Zhang. "Whichever theory is true, you can draw the same practical conclusion about what's best for kids' vision: less time hunched over screens, more time on outdoor activities." Beyond that, treatments that slow myopia progression — such as OrthoK, multifocal soft contact lenses, and atropine eye drops — may be your best bet at preserving your child's eyesight.

Social media is abuzz with news of a possible class-action lawsuit against Tylenol on behalf of women who took it during pregnancy. But "while there is a lot of correlational evidence linking Tylenol during pregnancy with autism or ADHD diagnoses in children, this evidence is largely bad, in the sense of leaving us skeptical about causality," says Emily Oster in ParentData. All of the studies that link Tylenol to pregnancy outcomes are observational, which makes it very difficult to know whether the results are explained by differences (such as age, education, or smoking behavior) between the groups of women who took Tylenol during pregnancy and those who didn't. This doesn't mean "there is nothing in the data that would raise concerns for anyone about long-term acetaminophen exposure," Oster writes, but "I also think that the quality of the data is largely very poor."

Growing pains are common, but there's little consensus on their scope or cause, writes Elizabeth Chang in The Washington Post. A recent review of studies on growing pain found that "only half of the studies mentioned lower limb pain; only 48 percent of the studies reported that the pain came in the evening; and only 42 percent said it was episodic or recurrent," writes Chang. More than 8 in 10 studies didn't specify the age that the pains emerged, and a whopping 93 percent made no reference to growth. Studies floated a variety of causes, including "issues related to anatomy (hypermobility, knock knees, or low-bone-mineral density, for example), psychological issues such as stress, vascular issues such as skeletal blood flow, and metabolic problems such as low vitamin D levels." But the evidence supporting any one of them is thin to non-existent.

Children exposed to cannabis in the womb show elevated rates of depression, anxiety, and other psychiatric conditions in early adolescence, according to research from Washington University in St. Louis. The new study builds on research from 2020, which showed that prenatal cannabis exposure put kids at a slightly higher risk of sleep problems, lower birth weight, and lower cognitive performance. In both studies, the impact was strongest when exposure to cannabis persisted after the pregnancy was known. The researchers will continue to follow the cohort into adolescence, "when a large proportion of mental health diagnoses occur," said David Baranger, a postdoctoral researcher in the lab conducting the research. "Once they hit 14 or 15, we're expecting to see further increases in mental health disorders or other psychiatric conditions — increases that will continue into the kids' early 20s," Baranger said.