Protecting Pregnant Women and Children From Perchlorate Act of 2008 - Amends the Safe Drinking Water Act to require the Administrator of the Environmental Protection Agency (EPA) to: (1) publish (within 90 days) a health advisory for perchlorate that is fully protective, with an adequate margin of safety, of the health of vulnerable persons (including pregnant women, infants, and children), taking into consideration body weight, exposure patterns, and all routes of exposure; and (2) propose (within nine months) and finalize (within 18 months) a national primary drinking water regulation for perchlorate that is protective of vulnerable persons and the maximum contaminant level of which is as close to the maximum contaminant level goal for perchlorate, and as protective of vulnerable persons, as is feasible.