WASHINGTON — Bowing to privacy concerns, the Obama administration reversed itself Friday, scaling back the release of consumers’ personal information from the government’s health insurance website to private companies with a commercial interest in the data.

The administration made the changes to HealthCare.gov after The Associated Press reported this week that the website was quietly sending consumers’ personal data to companies that specialize in advertising and analyzing Internet data for performance and marketing.

The personal details included age, income, ZIP code, tobacco use and whether a woman is pregnant.

That prompted lawmakers to demand an explanation, while privacy advocates called on the administration to make changes.

Analysis of the website Friday by the AP showed that the administration had made changes to reduce the outbound flow of personal information. Before that, the website was explicitly sending personal data to third-party sites.

The site is used by millions to sign up for coverage under the health care law, or to merely browse for insurance plans in their communities.

The changes were confirmed by Cooper Quintin, a staff technologist with the Electronic Frontier Foundation, a civil liberties group. Quintin called it “a great first step.”

An administration spokesman did not respond to a request for comment on Friday.