The pregnancy-induced remission typical of RA does not seem to occur in pregnant women with AS. The mechanisms for this difference are not understood, but appear to be related to different pathogenetic mechanisms operating in the two diseases. The vast majority of women with ankylosing spondylitis can expect to have the same rate of fertility, course of pregnancy and birth, and to give birth to normal healthy babies to the same extent as the normal female population. The chance for the offspring to contract AS later in life is somewhat increased.