As a result of the Supreme Court’s decision in Young v. UPS, the EEOC has issued updated guidelines on the Pregnancy discrimination Act and ADA as those laws apply to pregnant workers.
The updated guidelines are here: http://www.eeoc.gov/laws/guidance/pregnancy_guidance.cfm
The Supreme Court’s decision in Young v. UPS is here: http://www.supremecourt.gov/opinions/14pdf/12-1226_k5fl.pdf