Effects of aspirin on placenta and perinatal outcomes in patients with poor obstetric history

The aim of this study was to compare a low-dose aspirin treatment on placental and perinatal effects in the patients with poor obstetric history such as preeclampsia, intrauterine growth retardation (IUGR) in previous pregnancy.

This retrospective study of 86 pregnant women was conducted between April 2002 and June 2005. In this study period 364 placentas were examined and the patients with poor obstetric history such as IUGR and preeclampsia were selected. Then the patients were assigned to three groups; group 1 (n = 30) was composed of women with no risk in previous pregnancy; group 2 (n = 27) was composed of patients with poor obstetric history (e.g., preeclampsia, IUGR) who were treated with aspirin and patients in group 3 (n = 29) had poor obstetric history without any treatment (patients who were started to follow-up after 14 weeks of gestation). Patients in group 2 were treated with a low-dose aspirin (80 mg/day) as soon as a urinary pregnancy test was positive. Treatment was usually stopped at 34 completed weeks of gestation. On histopathologic examination of the placenta, uteroplacental vascular pathologic features and secondary villous damage (such as fibrinoid necrosis of desidual vessels, villous infarct, severely increased villous fibrosis, severely increased syncytiotrophoblast knotting, obliteration of the vessel lumen, severely increased villous hypervascularity) and also lesions involving coagulation (such as excessive perivillous fibrin deposition, multiple occlusive thrombi in uteroplacental vessels, avascular villi ) were examined.

There were no significant differences between the groups with respect to maternal age, body mass index at the first trimester and delivery. Also there were no significant differences among groups with respect to placental weight, fetal height, weight, gestational week, umbilical artery pH, pO2, pCO2 and base excess status. The incidences of preeclampsia were 3.3, 7.4, 6.8% and the incidences of IUGR were 6.7, 11.1, 6.8% in the groups, respectively (P > 0.05 for both). Although the percentages of all pathologic findings were higher in groups 2 and 3, these differences were not statistically important.

When low-dose aspirin is taken, starting at the beginning of pregnancy in patients with poor obstetric history, there are still high frequencies of uteroplacental vascular and related villous lesions persisted on placental bed. Also it has no beneficial effects on perinatal outcomes in these patients.