Although uncommon, secondary causes of hypertension are always a possibility in afected women. Thus, consideration is given to underlying chronic renal disease, connective-tissue disease, primary aldosteronism, Cushing syndrome, pheochromocytoma, and myriad other causes. That said, most pregnant women with antecedent hypertension will have otherwise uncomplicated disease.
Several factors increase the likelihood that pregnant women will have chronic hypertension. hree of those most frequently cited are ethnicity, obesity, and diabetes. As previously dis cussed, chronic hypertension has a population incidence that women (Kotchen, 2015). Related to this, hundreds of blood identified, including candidate genes for preeclampsia and chronic hypertension (Cowley, 2006; Ward, 2015).
The metabolic syndrome is a clinical cluster that includes hypertension, high blood sugar, excess fat at the waist, and abnormal cholesterol or triglyceride levels. This constellation is a risk marker for superimposed preeclampsia and for persistent postpartum hypertension Qeyabalan, 2015; Spaan, 2012). This is not surprising because obesity may increase the prevalence of chronic hypertension tenfold (Chap. 48, p. 938). In addition, obese women are more likely to develop superimposed preeclampsia. Diabetes is also prevalent in chronically hypertensive women, and its interplay with obesity and preeclampsia is overwhelming (Leon, 2016). In aforementioned study from the Nationwide Patient Sample, the most frequent comorbidities associated with chronic hypertension were pregestational diabetes-6.6 percent, thyroid disorders-4.1 percent, and collagen-vascular disease-0.6 percent (Bateman, 2012). Similar comorbidities were described by Cruz and associates (201a1).
• Efects of Pregnancy on
Blood pressure drops in early pregnancy in most women with chronic hypertension, and it rises again during the third trimester (Fig.
According to studies by Tihtonen and coworkers (2007), women with chronic hypertension have persistently elevated vascular resistance and possibly reduced intravascular volume expansion. Adverse outcomes in these women are dependent largely on whether superimposed preeclampsia develops. This may be related to observations reported by Hibbard and colleagues (2005, 2015) that arterial mechanical properties are most marked in women with superimposed preeclampsia.
.120 Chronic hypertension )..:ln 100 n (yellow) compared with blood pressures across pregnancy in 4589 healthy nulliparas (blue). (Data from August, 2015; Levine, 1997;
Sibai, 1990a.)
Chronic hypertension is associated with several adverse maternal and perinatal outcomes listed in Table 50-3. In sum, these adversities are directly related to severity and duration of hypertension before pregnancy and whether superimposed preeclampsia develops, especially early in gestation. Importantly, in women with mild chronic hypertension, outcomes are also related to blood pressure levels during pregnancy. At this time, however, there are no proven benefits of "tight" versus "lesstight" control of chronic hypertension during pregnancy, as discussed later (p. 982) (Magee, 2015).
Most women whose chronic hypertension is well controlled with therapy before pregnancy will do well. Even these women, however, are at increased risk for adverse outcomes. Complications are more likely with severe baseline hypertension and
TABLE 50-3. Some Adverse Efects of Chronic Hypertension on Maternal and Perinatal Outcomes
HELLP = hemolYSiS, elevated liver enzyme levels, low platelet cou nt.