A 26-year-old Nigerian woman is 16 weeks into her second pregnancy. The first pregnancy with the same partner was uneventful, and she gave birth to a healthy boy. An antibody reacting at 37°C with 10/10 panel cells is detected; the reaction is not affected by papain treatment of panel cells. The reaction with autologous cells is negative. The woman’s red cell phenotype is: O, C−, c+, D+, E−, e+, K−, k+, Jk (a+b+), Fy (a−b−), M+, N−, S−, s−. She had never been transfused.