I loved this book -- a thriller with an unexpected twist -- Lisa Lori 

Helen’s idyllic life—handsome architect husband, gorgeous Victorian house, and cherished baby on the way (after years of trying)—begins to change the day she attends her first prenatal class and meets Rachel, an unpredictable single mother-to-be. Rachel doesn’t seem very maternal: she smokes, drinks, and professes little interest in parenthood. Still, Helen is drawn to her. Maybe Rachel just needs a friend. And to be honest, Helen’s a bit lonely herself. At least Rachel is fun to be with. She makes Helen laugh, invites her confidences, and distracts her from her fears.