If a mother earned a salary for the daily work she does around the house and with the kids, she'd bring home $59,862 in 2013. According to an annual study from Insure.com, that figure is down from $60,182 last year and $61,436 in 2011, due to a drop in wages for several domestic jobs.

Flickr User Ed Yourdon

The Mother's Day Index looked at a number of jobs the average mother might perform, such as cooking, cleaning and shopping for the family. The wages equal what a family would have to pay out if someone else had to do those tasks all year.

"I feel like it's this ongoing hamster wheel that we're on," said Tracey Serebin, a mother and a family coach based in Ringwood, New Jersey. "It really is overlooked - all the juggling that moms do, especially moms that have more than one child."

The juggling gets even harder if the mother happens to work a full-time job on top of her at-home duties.

"Moms don't have a 40-hour workweek," Serebin added, noting a mother's help is needed seven days a week. "It's something that doesn't end."

According to the study, most men and women underestimate a mother's worth. When asked how much someone else would have to be paid to perform the mother's daily tasks, 56 percent of women and 62 percent of men said under $40,000 per year.