We report the case histories of two HIV-1 positive women in the third trimester of pregnancy who presented with acute lactic acidosis and acute pancreatitis, respectively. One case was fatal for mother and baby. Both women had been stable on regimens containing stavudine and didanosine for at least 2 years before their acute presentations. We speculate on the differential diagnosis, discuss possible reasons for an increased risk of these presentations in pregnant women taking antiretrovirals, and advocate increased vigilance of these women, particularly in the last trimester.