Melanie Dawn Williams, 28, was seven months pregnant and driving to a hospital on doctor's orders in 2005 when she ran a red light, a police report said.
Two officers chased her to the hospital, tackled her in the emergency room and dragged her, handcuffed, back outside, the report said.
Eventually a nurse came outside, found Williams bleeding from premature labor and insisted she be taken to the hospital's labor and delivery unit, where doctors successfully staved off labor.
She spent 10 days in the hospital. The officers were disciplined, The (Jacksonville) Florida Times-Union reported.
One officer told internal affairs investigators Williams hadn't mentioned being pregnant until they handcuffed her, but a panel of the 11th U.S. Circuit Court of Appeals in Atlanta said that didn't matter.
It said that once they knew Williams was in medical distress, police had no right to make an arrest.
But the judges said Williams could not pursue a separate excessive-force claim.
"Although we agree ... that the deputies' behavior was reprehensible, we disagree that the evidence supports a finding that the force was excessive," the judges said.
The appeals court sent the case back to Jacksonville for further proceedings.