Risk Factors for Placental Abruption: A Case-Control Study

Abstract

Background. Placental abruption (PlAb) is a complete or partial detachment of the placenta before child’s delivery. PlAb complicates about 1% of pregnancies and is a leading cause of vaginal bleeding in the second half of pregnancy, and an important cause of perinatal mortality and morbidity. The aim of this study was to investigate the risk factors of placental abruption, and measure the association between first trimester vaginal bleeding (FTBL) and placental abruption at pregnancy termination. Methods. A case-control study was conducted with 83 cases and 166 controls identified among 7,861women who delivered at tertiary and secondary levels three maternities in 2010 in Yerevan. Stata 10 statistical software was used for data analysis. Clinical and demographic variables were compared between the groups. Simple and multivariate logistic regression analyses were applied to identify independent risk factors. Results. After adjusting for confounders (age, body mass index, education, socioeconomic condition), the risk of developing PlAb was more than three times higher among women with three and more days of the FTBL (OR 3.6; p=0.01). The odds of developing PlAb was more than four times higher among women with preeclampsia (OR 4.6; p=0.001). A statistically significant interaction was detected between preeclampsia and maternal age. While there was no association between maternal age and PlAb among women with normal blood pressure, among women with preeclampsia each year increase in age was associated with 20% increased risk of PlAb. Women with less than 13 kg weight gain during pregnancy have twice higher risk of developing PlAb compared with those who gained 13 kg and more (OR 2.2; p=0.014). The similar association was found between higher education (>13 years) and PlAb (OR 2.1; p=0.018). Sleeping on back position increases the risk of PlAb by 20% (OR 1.2; p=0.021). Conclusions. Study has demonstrated that first-trimester vaginal bleeding is an independent risk factor for placental abruption, and patients who reported three and more days of the first trimester vaginal bleeding showed an increased risk of placental abruption.