To determine the bioavailability, pharmacokinetics, and short-term safety and tolerance of nevirapine in HIV-1 infected pregnant women and their newborns when nevirapine is given to the mother during active labor, and when their neonates are dosed during the first week of life. To determine the short-term safety profile of mothers receiving zidovudine (AZT) who received nevirapine during active labor, and their neonates who received no dose, a single dose, or multiple doses of nevirapine and who are receiving AZT during the first 6 weeks of life.