Return of Robin Roberts Brings Higher Ratings to \'Good Morning America\'

“Good Morning America” had its best morning in the ratings in three months when Robin Roberts returned to the show on Wednesday after a medical leave of absence, according to preliminary Nielsen ratings.

About 6.1 million viewers tuned in for Ms. Roberts’ much-touted comeback, giving the show its biggest audience since the morning after the presidential election in November.

The second-place network morning show, NBC’s “Today,” had somewhere between 4.9 million and 5.0 million viewers. (ABC and NBC shared slightly different sets of Nielsen numbers with reporters.) For “G.M.A.,” the ratings on Wednesday represented a bump of about 12 percent from its recent averages. For “Today,” the ratings were about flat.

What both networks care more about is the 25- to 54-year-old demographic, because advertising rates can rise and fall depending on the “demo,” as they call it.

The two shows remained basically tied in that demographic, ith “G.M.A.” reporting an advantage of just 36,000 viewers ages 25 to 54. “Today” was slightly ahead on Wednesday in a younger demographic, that of viewers ages 18 to 49. (The show’s main anchor, Matt Lauer, is on vacation this week.) The competition between “G.M.A.” and “Today” will be fierce for the next few months because the upfront advertising sales period starts in the spring.

Ms. Roberts, who is beloved by millions of “G.M.A.” viewers, left the show last August and underwent a bone marrow transplant in September to treat a rare blood disorder she contracted as a result of treatment for breast cancer in 2007.

She has described herself as eager to get back to work, and she was back on “G.M.A.” for a second day on Thursday. But concerns about her health persist, and both her doctors and her producers at ABC have said that her re-entry will take some time. To that end, she said on ABC’s “The View” on Thursday that the “G.M.A.” producer Tom Cibrowski ! had told her to “take tomorrow morning off.”

“It’s easing my way back in,” she said of her re-entry.

Though she won’t be on “G.M.A.” on Friday, Ms. Roberts does have an interview to tape with Michelle Obama. The interview will be televised next Tuesday.

Over the weekend Ms. Roberts will fly to Los Angeles, where she will appear on ABC’s coverage of the Academy Awards and co-host “G.M.A.” before dawn on Monday morning â€" a busy schedule for anyone, let alone a person still recovering from a bone marrow transplant.