RESUMEN
Gestational hypertension and preeclampsia are important maternal and fetal - infant complications and the second cause of maternal death [after embolism]. This study is a clinical trial was done on 64 women at preeclampsia risk. The patient came under study with convenience method .The control group I taking placebo in the morning, control group 2 taking placebo at bedtime, experimental group 1 taking 100 mg aspirin in the morning and experimental group 2 taking 100 mg aspirin at bedtime. This intervention started at 12 to 16 weeks of gestation and continued up to 32 weeks. Blood pressure monitoring device was recorded patient's blood pressure before and after taking drug at the end of each month for 24 hours until delivery. Clinical information of the patients was collected and registered in special form and was analysis with statistical method analysis variations at the level of 5% by using SPSS version 16. The age of participants were between 17-42 years with mean 28.71 SD +/- 5.87%.The systolic blood pressure mean at the time of enteringwere computedlo6.20 +/- 4.936% and the diastolic blood pressure 61.909 +/- 5.373%. 24 hour Blood reassure mean of the sampling who take aspirin before bedtimewas significantly less than control groups and group taking aspirin in the morningduring pregnancy [for systole and diastole P <0.001]. The effect of taking aspirin at bedtime is moreon blood pressure mean reduction compared with taking it in the morning and placebo in women at preeclampsia risk