Incidentally detected thrombocytopenia in healthy mothers and their infants.

The unexpected discovery of thrombocytopenia in an asymptomatic pregnant woman--often considered to be equivalent to the diagnosis of idiopathic thrombocytopenic purpura--leads to a variety of interventions, including delivery by cesarean section. However, the actual risk to mothers and their infants posed by incidentally noted thrombocytopenia is not known. To investigate this issue, we performed a prospective study of a group of normal women who delivered at our medical center and their infants during a period of one year. Of the 2263 women who delivered during the year, 1357 were considered to be normal. One hundred twelve of the women (8.3 percent) had mild thrombocytopenia (range of platelet counts, 97 to 150 x 10(9) per liter). The thrombocytopenia had no discernible clinical effect on the women or their infants. The frequency of thrombocytopenia in babies born to this group of women was not appreciably different from that in babies born to the other normal patients who did not have thrombocytopenia, and none of the infants of women with thrombocytopenia had a platelet count of less than 100 x 10(9) per liter. This study demonstrates that the frequency of mild thrombocytopenia is high in normal pregnant women at term and that the thrombocytopenia appears to have no adverse effect on either the mothers or their infants. To perform obstetrical interventions such as cesarean section because of thrombocytopenia in these mothers is not justified.