Kim Turner holds her daughter Adelaide before a rally supporting paid family leave at City Hall in San Francisco on Tuesday. The San Francisco board of supervisors voted to require six weeks of fully paid leave for new parents.

SAN FRANCISCO — San Francisco approved a measure Tuesday making it the first place in the nation to require businesses to provide fully paid leave for new mothers and fathers to spend time with their new child.

Parental leave advocates say the issue is gaining momentum across the country much like the debate over a higher minimum wage.

They say the measure is needed because too many parents can’t afford to lose pay to take time off after a birth or adoption.

Some big companies and government entities already provide such benefits, but smaller businesses argue the action in San Francisco is another expensive mandate they can’t afford.

Here are some things to know about the measure:

THE MEASURE

The state of California currently allows workers to receive 55 percent of their pay for up to six weeks to bond with a new child. The money comes from a state insurance program funded by workers. The measure in San Francisco requires private employers to make up the remainder of a parent’s full pay for six weeks.

WHO IS AFFECTED?

The benefit applies to new mothers and fathers who work at least eight hours a week and spend at least 40 percent of their work week within San Francisco boundaries.

The regulation will be phased in, starting with businesses that employ 50 workers or more in January 2017.

Businesses with 35 to 49 workers must comply starting in July 2017, and businesses with 20 to 34 workers have until January 2018.

The legislation does not apply to the federal, state or other municipal governments.

GOVERNMENT eMPLOYEES

People who work for the city and county of San Francisco receive up to 12 weeks of paid leave. In comparison, the city of Portland and Multnomah County in Oregon offer six weeks to its employees. New York City offers six weeks of fully paid leave to its nonunion employees.

HOW DOES it COMPARE?

California, New Jersey and Rhode Island offer partial pay for new parents through state disability insurance programs. New York approved legislation last month that calls for partial pay for up to 12 weeks.

PRIVATE EMPLOYERS

Some big-name technology companies in hypercompetitive Silicon Valley offer generous paid leave benefits to attract and retain workers. Netflix, for example, offers up to one year of paid leave for salaried workers and 12 to 16 weeks for hourly workers. Twitter announced Tuesday it would provide 20 weeks of paid leave starting May 1.