Risk of thrombocytopenia in the infants of mothers with idiopathic thrombocytopenia.

Twenty-nine of 27,662 pregnant women had autoimmune thrombocytopenia at the time of delivery at King Khalid University Hospital over 6 years starting June 1986. Twenty-six had idiopathic thrombocytopenic purpura (ITP), gave birth to 33 infants, of which 22 were by spontaneous vaginal delivery, eight by lower segment cesarean section, and two by forceps. Fourteen (44%) of the 32 living infants had platelets less than 150 x 10(9)/L and four (12.5%) had severe thrombocytopenia (platelets less than 50 x 10(9)/L). The mothers' platelets of less than 50 x 10(9)/L at delivery were found to be predictive of thrombocytopenia in their infants (P < 0.027), compared with mothers' platelet of more than 50 x 10(9)/L. Maternal treatment with prednisone did not seem to have significant effect on infants' platelets (P < 0.89). All infants with severe thrombocytopenia (less than 50 x 10(9)/L) at birth had ultrasound done and were found to be normal. We conclude that: (1) steroid given to pregnant women with ITP does not increase infants' platelet counts, (2) severe thrombocytopenia in the mothers (platelet counts less than 50 x 10(9)/L) is highly predictive of thrombocytopenia in their infants; (3) cesarean section should be limited to the mother with severe thrombocytopenia if fetal scalp platelets are less than 50 x 10(9)/L.