<human>:  When a woman is in labor, what is the first thing that happens?
<bot>: The first thing that happens is that the cervix dilates. This is a process that happens over the course of several hours. The cervix is the opening of the uterus, and it is the place where the baby is born. The cervix is made of muscle, and it is the muscle that is responsible for the dilation of the cervix.