ST. LOUIS — The nonprofit Catholic organization SSM Health is providing birth control pills at the 26 clinics inside St. Louis-area Walgreens stores that it began operating Thursday, an SSM spokesman said. Four groups, led by the American Civil Liberties Union, wrote letters to SSM and Walgreens on Aug. 18, asking whether the clinics would be restricted by religious doctrine from allowing consultations on birth control and referrals for abortions. SSM spokesman Jason Merrill said in a phone interview Thursday that the clinics will provide 30-day refills for contraceptive pills previously prescribed by a physician — the same policy carried by the clinics previously run in-house by Walgreens.