This evidence supports the theory that suicide can be an adaptive behavior - people who commit suicide are people of low reproductive value anyway (i.e., those with few or no children and little likelihood of producing any viable offspring). Suicide may be an effective means of accomplishing one's evolved ends - "make sure your genes live on." When one consumes more than one contributes to one's relatives, one's continued existence is a drain on evolutionary fitness.
Of course, that's not how the study phrases it. Rather, motherhood is seen as having a "protective effect" against suicide - as if suicide were gonorrhea, and motherhood a condom.
Looking at 30 years' worth of data on 1.3 million Taiwanese mothers, [Dr. Chun-Yuh Yang, of Kaohsiung Medical University in Taiwan] found that women with two children were 39 percent less likely than those with one child to commit suicide.
That risk was 60 percent lower among women with three or more children, Yang reports in the Canadian Medical Association Journal.
Thus the species continues.
(As do I, despite speculation to the contrary.)