Women are underrepresented in the ranks of science professors in math-intensive fields—45 percent of undergraduate degrees and 29 percent of PhDs in math go to women, but in 2007 only 4.4 to 12.3 percent of the full professors in chemistry, physics, mathematics, engineering and computer science were women at the top 100 U.S. universities.

Why? A new study by Wendy Williams and Stephen Ceci, human development professors at Cornell’s Institute for Women in Science, argues that it’s not discrimination: Women who do stay in the field are as successful as men at achieving tenure-track positions, publishing their work and earning grants. Instead, most women who opt out do it because they’re having (or planning to have) babies. Most scientists apply for tenure-track jobs in their late 20s and early 30s. If a candidate wins a position, she often has to relocate for it and then devote about six years to the research, teaching, publishing and grant applications necessary to create an impressive portfolio—an intensive workload that many women don't want to take on while they're raising young children.

The authors suggest that universities reconsider the tenure model that was created when only men (most with stay-at-home wives) achieved full professorships. Alternative paths, such as part-time tenure-track jobs and shared full-time positions, could help women stay in the field while their kids are small; making sure there’s no penalty for taking time off from a career would help women pick up where they left off when their family demands are more manageable.

The article appears in the March-April issue of the journal American Scientist.

(Image: Marie Curie)