RESUMEN
Feto-maternal transfusion was studied in 2,000 pregnant Thai women. The technic used in the study was modified acid election test. The population were divided into five group, first trimester, second trimester, third, during delivery and non pregnant women. Over all fetomaternal transfusion occurred in 1,055 women (65.94%). In first trimester, second trimester, third trimester and during delivery were 53.5 per cent, 63.0 per cent, 71.1 per cent and 75.7 per cent respectively. The data were significantly different from non pregnant women (p < 0.0001). The volume of transfusion was varied from 0 to 12.65 ml and greater in the advancing gestational age. In first trimester, second trimester, third trimester and during delivery the volume of transfusion were 0.07, 0.08, 0.13, 0.19 ml respectively.