BIRMINGHAM, Ala.  “It’s going to be cold, and some pressure, O.K.?”

The medical assistant guided the gelled ultrasound transducer across the pregnant woman’s belly. The patient, a 36-year-old divorced woman named Laura, stared straight ahead, away from the grainy image on the screen to her side.

The technician told Laura she was at 11 weeks. “Do you want to see your ultrasound?” she asked. “I’d rather not,” Laura answered promptly.

Laura, who asked that her last name not be used, had come to the New Woman All Women Health Care clinic in Birmingham with her mind set on having an abortion. And she felt that seeing the image of her bean-size fetus would only unleash her already hormonal emotions, without changing her mind.

“It just would have added to the pain of what is already a difficult decision,” she said later.

Over the last decade, ultrasound has quietly become a new front in the grinding state-by-state battle over abortion. With backing from anti-abortion groups, which argue that sonograms can help persuade women to preserve pregnancies, 20 states have enacted laws that encourage or require the use of ultrasound.