In 1965, American mothers spent an average of eight hours a week on paid work and 10 hours a week on child care. In 2011, they worked 21 hours a week—and spent 14 hours on child care. That is, even as they became much more likely to spend a significant amount of time at work, moms came to devote more time, not less, to their kids. Do you think children benefited from that change? Restricting the question to today, are kids who spend more time with their moms more likely to do well on standard academic and behavioral measures?

I had always assumed that all else equal, the time mothers spend with their kids would be associated more positive outcomes for them—better academic achievement, fewer emotional and behavior problems, less risk-taking in adolescence. But a new study by sociologists Melissa Milkie, Kei Nomaguchi, and Kathleen Denny in the Journal of Marriage and Family examined exactly that question and found essentially null results: “In childhood and adolescence, the amount of maternal time did not matter for offspring behaviors, emotions, or academics.”

The researchers used data from the Child Development Supplement of the Panel Study of Income Dynamics on about 1,600 kids (ages three to 11), roughly half of whom they followed into adolescence (ages 12 to 18), and looked at both “accessible time”—time mothers spent in the same place as their kids, but not actively doing things with them—and “engaged time,” or “focused time in shared activities,” in both cases excluding the hours when fathers were also present. Time diaries from a weekday and a weekend day allowed for weekly estimates for the two measures. Of course, the researchers controlled for several factors: the number of children in the household; the child’s age, gender, and race; and the mother’s weekly work hours, age, and psychological distress. 

The children’s outcomes included: 1) behavior problems, in which mothers reported on factors such as “whether the child had ever cheated or told lies, argued too much, had difficulty concentrating, bullied or was cruel or mean to others, or was restless or overly active,” 2) emotional problems, as measured by mothers’ assessment of “whether the child felt that no one loved him or her, was too fearful or anxious, was easily confused, was unhappy, was withdrawn, or was too dependent on others,” etc., 3) academic performance, meaning kids’ scores on standardized tests, and 4) for adolescents only, risk-taking and delinquent behaviors, measured by adolescents’ reports of their substance use, sexual activity, and how many times in the last six months they had skipped school, stolen, broken curfew, and so on. 

After crunching the numbers on all these factors, Milkie, Nomaguchi, and Denny found a surprising result: Although socioeconomic status and family structure were linked with kids’ outcomes in predictable ways, “there were no statistically significant associations between maternal time of either type and any child outcome.” For adolescents, the same held true, except that engaged mother time was negatively related to delinquent behavior (even here, the effect size was small). The results did not vary by families’ socioeconomic status.

The researchers then repeated the same analyses for father time—the time kids spent with their fathers when their mothers weren’t around—and parent time, when both parents were present. Like mother time, father time and parent time were not linked to children’s academic performance or emotional and behavior problems. But for adolescents, more parent time—time spent with both parents together—was linked to several positive outcomes: “Time spent engaged with both parents was associated with fewer behavioral problems, better performance in math, less substance use, and less delinquent behavior. Time spent with both parents accessible to adolescents was associated with less substance use.”

As always, several caveats are in order. Milkie et al. note the possibility that “mothers who spend more time with children could be negatively selected into being with them more often,” for instance by serious health problems that leave them unable to leave the house much and put a strain on family life. If this is the case, their results may be skewed. Also, the youngest kids in their study were three years old, so the study is not relevant to debates over parental leave following a child’s birth or over whether day care or parental care is better for toddlers.

Furthermore, the study did not measure mothers’ or fathers’ warmth or sensitivity, nor did it distinguish between the many forms “engaged time” can take (e.g. reading a book or eating dinner together versus watching TV together), and other studies verify the common-sense assumption that these factors are highly relevant to kids’ flourishing. In short, the researchers caution, “this is not the definitive study that trumpets ‘Mothers Do Not Matter for Children.'” 

Despite these shortcomings, there are a few possible takeaways for parents: Realize that your kids need you during adolescence, not just in childhood, and try to spend time together as a family rather than hand kids off from one parent to the other. Finally, instead of going to extremes to maximize the number of minutes each parent spends with the kids, focus on ensuring that the time you do have together is spent well.