Hospitals and medical practices across the United States are bracing for confusion and administrative hassles as new insurance plans under President Barack Obama's healthcare law take effect on Wednesday.

More than 2 million people enrolled in private plans offered under the Affordable Care Act, popularly known as Obamacare, during the initial sign-up period for health benefits starting Jan. 1. Enrollment began in October and lasts through March, but Americans in most states had to enroll by last week to get coverage that takes effect with the start of the new year.