Prevention of recurrent idiopathic fetal growth retardation by low-dose aspirin and dipyridamole.

In a controlled, nonrandomized trial a treatment group of 24 multigravid women with a history of at least two previous pregnancies, all complicated by idiopathic fetal growth retardation and placental infarction, received 1 to 1.6 mg/kg aspirin and 225 mg dipyridamole daily from 16 to 34 weeks' gestation in a total of 30 pregnancies. The end-point measure of the study was birth weight related to gestational age. Results obtained in the treatment group were compared with those in 27 pregnancies of a control group of 24 multigravid women with a similar history of recurrent fetal growth retardation who received comparable antenatal care without low dose aspirin and dipyridamole. Fetal growth retardation occurred in 61% of the control pregnancies and in only 13% of treated pregnancies; severe fetal growth retardation was not observed in treated pregnancies, but it occurred in 27% of the control group. In treated women, platelet cyclo-oxygenase activity was suppressed to 5% to 10% of its pretreatment level, but no effect on vascular prostacyclin production was demonstrated. Treatment did not produce adverse effects in mothers or infants. Low-dose aspirin and dipyridamole direct prostacyclin/thromboxane A2 balance in pregnancy to the dominance of prostacyclin and may thus prevent idiopathic uteroplacental insufficiency and fetal growth retardation in high-risk patients.