Interpretation
The prevalence of placental abruption varies across regions. In the present study, the incidence of placental abruption was 0.4%, which is similar to that reported in the Nordic countries (0.4–0.5%) and is lower than that reported for the US (0.6–1.0%).2Postpartum hemorrhage (PPH) is the most frequently reported maternal morbidity associated with the placental abruption, and PPH, as a consequence of placental abruption, elevates the incidence of maternal blood transfusion. The rate of transfusion due to placental abruption in the present study was 1.7%, which is lower than that reported in the previous studies (2.4–14.6%).1 The distinctive difference in maternal transfusion rate for women with placental abruption may due to different diagnosis criteria for placental abruption in each study. The diagnosis of abruption is primarily clinical, but sometimes findings from the imaging, laboratory, and postpartum pathologic studies can be used to support the clinical diagnosis.1 However, to date, there is no gold standard for diagnosing placental abruption.
The findings of the present study indicate that half of the placental abruption cases occurred before the 37 weeks of gestation. Preterm birth (PTB) is one of the most frequently reported obstetric outcomes associated with the placental abruption.1 PTB has two clinical subtypes, viz., spontaneous PTB and medically indicated PTB; the latter occurs due to HDP.8 Placental abruption can lead to both spontaneous and medically indicated PTB. Spontaneous PTB due to placental abruption is thought to be the result of bleeding from the separation of the placenta, which irritates the uterine lining and stimulates uterine contractions leading to PTB.17Medically indicated PTB because of placental abruption is usually conducted by CS to reduce the risk of maternal and perinatal morbidity and mortality.18 The present study showed high prevalence of CS (62.2%) for cases with placental abruption, and high percentage of CS was before 37 weeks of gestation (Figure 2B), suggesting that most cases of PTB were medically indicated.
Placental abruption is a complex complication of pregnancy. Although several risk factors for placental abruption are known, its etiopathogenesis is not fully understood. Ananth et al. reported that instead of the number of previous deliveries, the maternal age was an independent risk factor for placental abruption.19 The findings of the present study are consistent with those reported by Ananth et al. The underlying reason for why advanced maternal age increases the risk of placental abruption is speculative. Most abruptions appear to be related to a chronic placental disease process, wherein, abnormalities in the early development of the spiral arteries, which could be affected by maternal age, can lead to decidual necrosis, placental inflammation, and possibly infarction, ultimately resulting in vascular disruption and bleeding.20–22 A few studies have reported the association between teenage pregnancy and placental abruption. Kyozuka et al., using descriptive analysis, reported that maternal age <20 years is responsible for the highest occurrence of severe maternal complications such as HDP and placental abruption.9 They concluded that low socio-economic status of teenagers could be associated with the high occurrence of severe maternal complications. The underlying reason for why teenage pregnancy is an independent risk factor for placental abruption in the present analysis is more speculative. However, the findings of the present study must be interpreted with caution because teenage women are likely to be associated with less education, low income, and malnutrition, which have not been considered as confounding factors in the present analysis. The placental abruption during teenage could be due to direct mechanical events such as blunt abdominal trauma and/or rapid uterine decompression, which are more eventful in young maternal age.23