Data from Ananth/ 1999a/b/ 2004/ 2007; Aviram/ 2015; Gutvirtz/ 2016; Morgan/ 2016; Nath/ 2007/ 2008; Ruiter/ 2015.
(Okby, 2017; Pritchard, 1991). ace or ethnicity also appears to be important. In almost 366,000 deliveries at Parkland Hospital, abruption severe enough to kill the fetus was most common in black and white women-1 in 200, less so in Asian women-1 in 300, and least common in Latin-American women-1 in 350 (Pritchard, 1991). Aomilial association was found in an analysis of a Norwegian population-based registry (Rasmussen, 2009). If a woman had a severe abruption, the risk for her sister was doubled.
Some form of hypertension is the most frequent condition associated with placental abruption. his includes gestational hypertension, preeclampsia, chronic hypertension, or a combination thereof. In a report by Pritchard and colleagues (1991) that described 408 women with placental abruption and fetal demise, hypertension was apparent in half once hypovolemia was corrected. Half of these latter women-a fourth of all 408-had chronic hypertension. Looked at another way, one Maternal-Fetal Medicine Units (MFMU) Network study found that 1.5 percent of pregnant women with chronic hypertension sufered placental abruption (Sibai, 1998). As discussed in Chapter 50 (p. 978), at Parkland Hospital, the frequency of placental abruption in treated chronically hypertensive women was almost 1 percent, which was threefold higher than the 0.3-percent baseline C..10rgan, 2016).
Chronic hypertension with superimposed preeclampsia or with fetal-growth restriction confers an even greater risk (Ananth, 2007). Even so, the severity of hypertension does not necessarily correlate with abruption incidence (Morgan, 2016; Zetterstrom, 2005). The long-term efects of these associations are apparent from the signiicantly elevated cardiovascular mortality risk in women with prior abruption, with or without chronic hypertension (DeRoo, 2016; Pariente, 2013). Observations from the Magpie Trial Collaborative Group suggest that women with preeclampsia, with or without chronic hypertension, given magnesium sulfate may have a reduced risk for abruption (Altman, 2002).
he abruption risk substantially rises when placental membranes rupture before term (American College of Obstetricians and Gynecologists, 2016a; Hackney, 2016). Major and colleagues (1995) reported that 5 percent of 756 women with ruptured membranes between 20 and 36 weeks' gestation developed an abruption. It was 17 percent with previable prematurely ruptured membranes (Kibel, 2016). he risk for abruption with preterm rupture is further increased with comorbid infection (Ananth, 2004). In these cases, inlammation and infection as well as preterm delivery may be primary causes leading to abruption (Nath, 2007, 2008).
Somewhat related, Aviram and coworkers (2015) found an eightfold higher abruption risk in pregnancies �34 weeks if hydramnios was comorbid. Abrupt uterine decompression during membrane rupture may be an inciting factor.