Case-control study of antenatal cocaine use and platelet levels.

OBJECTIVE Our aim was to determine the prevalence of thrombocytopenia in pregnant patients who did and did not use cocaine. STUDY DESIGN A 1:1 case-control study of 326 patients attending an inner-city, neighborhood-based antenatal program between January 1992 and December 1998 is presented. Data concerning cocaine use (history and urine toxicology study) and platelet count, along with gestational age, were compared by nonparametric techniques (chi2 test, Fisher exact test, Wilcoxon rank sums, and receiver operating characteristic curve). RESULTS The prevalence of thrombocytopenia during pregnancy was not different between cocaine-using patients (13/160; 8.1%) and nonusing patients (11/160; 6.9%; difference not significant). In patients who abused cocaine and for whom both positive and negative urine screening results were obtained concomitantly with platelet levels, no difference in platelet counts was evident. Overall, thrombocytopenia occurred more often in the third trimester than earlier in pregnancy for both control and cocaine-using pregnant women. CONCLUSION Cocaine use among pregnant women was not associated with thrombocytopenia. A low platelet count was found more often later in pregnancy.