https://phys.org/news/2018-06-dads-theyre-harder-workers.html

"Although women typically experience a dip in earnings after becoming mothers, our study confirms the prevalence of the so-called 'daddy bonus'— the wage boost that men enjoy when they become fathers," said lead author Sylvia Fuller, associate professor in the UBC department of sociology. "Our findings suggest that employers are more likely to see fathers as deserving of promotions and higher wages because of an unfair assumption that men are the breadwinners in their families, and are therefore more likely to be hardworking and dependable. Of course, that assumption isn't always true."

For the study, the researchers analyzed data from Statistic Canada's Canadian Workplace and Employee Survey, gathered from 1999 to 2005. The sample included 18,730 men between 24 and 44 years of age in 5,020 workplaces. The researchers focused on wage differences within workplaces and limited their study to white men because including non-white men would require a separate analysis due to the wage gap that exists between white men and other racial groups.