Reliable data from 1840 through 2002 indicates life expectancy has risen linearly for men and women, albeit more slowly for men. For women the increase has been almost three months per year, for men almost 2.7 months per year. In light of steady increase, without any sign of limitation, the suggestion that life expectancy will top out must be treated with caution. Scientists Oeppen and Vaupel observe that experts who assert that "life expectancy is approaching a ceiling ... have repeatedly been proven wrong." It is thought that life expectancy for women has increased more dramatically owing to the considerable advances in medicine related to childbirth.