why does tita deliver rosaura's baby? who helps her?

After sending Nicholas off Tita was surprised to see Pedro packing up the carriage. And she soon discovered that Rosaura was in labor and Pedro needed to get Dr Brown to deliver the baby. On his way out Pedro asked Tita to watch after Rosaura in his absence. Since Chencha and Mama Elena were also gone (they went to fetch baby supplies for the newborn) Tita had no choice but to help her sister. Faced with this new responsibility, Tita cursed her teachers and her mother for never having taught her how to deliver a baby. Though she knew nothing at childbirth, Tita was the only one present when Rosaura gave labor for on that day Federal troops captured Pedro preventing him from getting to Dr. Brown.