For those of you who are actually knowledgeable about economics, i.e. haven't drunk the leftist Kool-Aid, it will be a nice refresher.
While the new mom is taking a year out of her occupation, everyone else is gaining experience and becoming more valuable. In addition, it's hard to fathom that a year's removal will not cause some skills and knowledge to atrophy, especially in fast-moving technological or information fields.
And none of this takes into account the other considerable costs of the hiatus, all of which by law are borne by the employer. A job search is required for a replacement. The replacement must be trained. The replacement will likely function at a lower proficiency. The replacement must be fired or transferred at the end of leave. And the returning worker will need to get back up to speed on what has happened during her absence.
But let's switch gears here. Underlying all of this is a massive and incorrect assumption by the authors that the "economic impact of motherhood" is somehow limited only to the mother's earning power in the economy. It ignores the effect of motherhood on the economy in ways that can't be measured by payroll statistics. Having and properly raising children is a vastly underestimated revenue generator that is often ignored for ideological reasons, hence its exclusion from GDP calculations.
