The Walk For Life coincides with the anniversary of Roe vs. Wade, when the US Supreme court legalized abortion in 1973.
Maria Lopez brought her three kids from Stockton.
"The unborn life has to be respected because it's a creation of God," said Lopez.
Before the march, there was a rally at Civic Center.
The crowd was clearly energized , after President Trump became the first sitting president to address Friday's March for life in Washington, vowing his support.
"Coming from our leader, it's a powerful message that he's supporting life," said Scott Segerblom from San Mateo.
On Market street, pro-choice activists made their presence known to the marchers hoping their message was heard.
"I hope you take time to consider how it feels to be in a position you need to make a choice, you have to respond to your body over an idea," said San Francisco activist Castle Laws.
Organizers say more than 10,000 people took part in the Walk for Life. Police say event was peaceful.
For public transportation, SFMTA issues travel advisories and notifications when bus lines are rerouted.