Mary Beth Whitehead, who in the landmark Baby M case lost custody of the girl she bore under a surrogate contract, is pregnant by a man other than her estranged husband, the girl's court-appointed lawyer said. Lorraine Abraham said she was obliged as an officer of the court to notify the New Jersey Supreme Court of Whitehead's pregnancy. Abraham said her notification to the court carried no recommendation for changes in Mrs. Whitehead's visitation with the baby. Abraham said Whitehead, who is living with her two other children in East Brunswick, N.J., is pregnant by a man identified as "Dean." She refused to say how she learned of the pregnancy. Whitehead's attorney refused to comment. Whitehead separated in August from her husband, Richard, who, according to court papers and testimony, had a vasectomy several years ago.