I did a quick search on cortisol and pregnancy. More cortisol is produced.
Growth hormone and more blood volume are produced during pregnancy. I wonder if growth hormone has any positive effect on lips. Also, more Thyroxine (T4 & T3) is produced. This is needed for the development of the central nervous system and increases oxygen consumption. Prolactin is important for the regulation of the mother's metabolism during the pregnancy and assists in the stimulation of immune system cell growth.