The hair follicles have a growth cycle of three years.  At any given time about 85% of the follicles are in the growth phase, while the remaining 15% are in the dormant phase, preparatory to being shed.  There are many women who find that during pregnancy their hair is better looking, fuller and brighter.  This is due because during pregnancy a greater percentage of the follicles are in the growth phase and fewer hairs are shed.  Two to three months after the pregnancy this phase ends, leading to more hair being shed and a certain thinning of the hair.  This phenomenon is generally temporary and the hair returns to its accustomed abundance within one to six months.  In a small percentage of women who have a hereditary tendency to thin hair, it will remain thinner than it was before the pregnancy.  Temporary hair loss may also occur in pregnancies which ended in abortions or miscarriages.  Cases of temporarily increased body hair during pregnancy have also been reported.