One reason a girl's hips grow wider is to allow a baby to pass through if she has one. This is also why a female's pelvis and hip joints are very different from a male's. Also, the nipples begin to grow more prominent and more sensitive. One reason for this is to prepare a girl to later make milk for her baby, when and if she has one. The vulva becomes fuller, and for some, more sensitive, and soft, darkish hair grows around the vulva, later becoming curly, thicker and coarse.
Some women prefer to remove that hair and keep the vulva bare for a variety of reasons.
This is an individual choice, sometimes because of today's bikinis, but most women keep what nature gives them and simply keep it trimmed not to show around the bikini lines. Things are happening on the inside of the body, too. The ovaries gradually grow larger, and the vagina begins to produce a whitish fluid that may flow out of the vagina, the purpose of which is to help keep it clean and healthy. Body has a sudden growth spurt, gaining weight and growing taller. Shoulders and chest grow broader.