Ms. Abedin, 35, is in the early stages of pregnancy, according to three people with knowledge of the situation.
The pregnancy, which the couple has disclosed to close friends and family, adds a new dimension to questions about the future of their marriage.
The news comes just days after Weiner admitted that he had sent lewd pictures of himself to a woman over Twitter. During the press conference, Weiner apologized to his wife and said they were planning on staying together.
"We have been through a great deal together, and we will weather this," he said. "I love her very much, and she loves me."