Most countries have at least some length of maternity leave required by law. Part of the explanation for why maternity leave is necessary almost always references the assumed developmental benefits for children over the long term.

A 2011 paper for the National Bureau of Economic Research, “Maternity Leave and Children’s Cognitive and Behavioral Development,” examined long-term health effects by tracking the length of maternity leave mothers had taken and looking at outcomes for their children at ages 4 and 5. Using data from Canadian families, the researchers compare groups of children who were born directly before and directly after passage of legislation that extended job-protected, partially compensated maternity leave from roughly 6 months to 1 year.

The study’s major findings include:

• Under the longer maternity leave policy, children did, predictably, receive an increase in direct maternal care. This had a “substantial impact on the maternal care children receive in their first year of life, with consequent impacts on inputs thought significant to development such as full time maternal employment, non-licensed non-parental care, breastfeeding and exclusive breastfeeding duration.”
• However, there was actually a very small decline in cognitive skills for the children whose mothers were on leave under the new one-year policy, compared to those children whose mothers lived with the older six-month policy. Children scored less than 9% of a standard deviation lower on vocabulary and less than 20% of a standard deviation on math for every extra month of maternity leave. The researchers caution, “In interpreting the negative impacts on the cognitive measures it is important to note that they are small.” Overall, this suggests the timing of the mother’s return to work may be important.
• Among behavioral factors correlated, only the association between increased maternity leave and reductions in the chances of hyperactivity was actually statistically significant.

The study’s authors state that, overall, the policy changes “had no positive effect on indices of children’s cognitive and behavioral development.” They conclude that their results “highlight the possibility that child development is not monotonically increasing in the amount of maternal care received in the first year — there may be better and worse times for mothers to make the transition back to work in this period. Because ‘more is better’ appears to be the working assumption of maternity leave laws in many countries, there is clearly a need to better understand the developmental consequences of mothers’ return to work over the ages typically spanned by these policies.”

Tags: children, parenting, cognition