Hypertensive disorders of pregnancy [HDP] represent a major cause of pregnancy-associated morbidity and mortality. These disorders have far-reaching consequences that extend well beyond the pregnancy and the immediate postpartum period. According to the Centers for Disease Control [CDC], HDP, including preeclampsia, accounts for nearly 7% of all maternal deaths []. HDP consists of a myriad of diagnoses, including chronic hypertension, gestational hypertension, preeclampsia, preeclampsia with severe features, and eclampsia [, ]. Similar to chronic hypertension, data suggest that preeclampsia has significant sequelae later in life. Therefore, a thorough understanding of the pathogenesis and prediction of HDP and its implications on short- and long-term health outcomes is crucial to provide optimal care to pregnant patients, especially as they transition out of the immediate postpartum period.
2. Risks and diagnosis
To improve long-term morbidity in the pregnant patient, minimizing the development of disease and early detection are paramount. No perfect prediction model exists to identify all patients who will develop HDP accurately nor define those at greatest risk of long-term morbidity. However, risk factors for the disease have been identified. As determined by the American College of Obstetrics and Gynecology [ACOG], risk factors for the development of preeclampsia include prior preeclampsia, chronic hypertension, diabetes, renal disease, autoimmune diseases such as lupus, and multifetal gestations [, , ]. Traditionally, the Black race has been identified as a risk factor for the development of HDP, with Black people having much higher rates of preeclampsia compared to White counterparts []. Recent research into health inequities, however, has questioned whether one’s race or ethnicity is a concrete risk factor for HDP or whether race and ethnicity are merely reflective of unequal access to care and unfavorable socio-economic conditions present in the healthcare system and society.
2.1. Diagnosis
Preeclampsia and HDP have well-established guidelines that aid clinicians in diagnosis []. [, ] Chronic hypertension is defined as a diagnosis that predates the pregnancy or blood pressure elevations [≥ 140/90] diagnosed prior to 20 weeks on two occasions at least 4 h apart []. Though these patients have a diagnosis of chronic hypertension prior to pregnancy, they remain at risk of worsening hypertension and the development of preeclampsia. Gestational hypertension is diagnosed with two elevated blood pressure readings ≥140/90 [defined as mild range blood pressures] after 20 weeks on two occasions at least 4 h apart []. Patients with this diagnosis lack the overt signs and symptoms of preeclampsia, though they are at increased risk of developing preeclampsia. Patients diagnosed earlier in pregnancy have a higher risk of progression to preeclampsia, with 15–25% of patients ultimately developing preeclampsia []. This risk of progression increases the earlier a patient is diagnosed and necessitates close patient monitoring.
Table 1. Diagnostic criteria for HDP.
Preeclampsia itself is defined as newly elevated blood pressure ≥ 140/90 after 20 weeks’ gestation in addition to proteinuria defined as 300 mg or more in a 24-h urine specimen, or a protein/creatinine ratio of 0.3 or more, or 2+ protein on urine dipstick [used if other quantitative methods are unavailable] []. A patient meeting these criteria is diagnosed with preeclampsia without severe features. It is important to recognize that there are other ways to meet the criteria for preeclampsia, all of which upstage the disease process to preeclampsia with severe features. Differentiating these two entities is important for management decisions and pregnancy implications. Preeclampsia with severe features represents a more severe form of the disease and has various diagnostic criteria, which can generally be divided into three main categories: blood pressure values [severe range blood pressures defined as ≥160/110], laboratory values, and symptomatology. Patients with blood pressure elevations of ≥160/110 [with either systolic or diastolic elevations] with two readings at least 4 h apart or continuous severe range blood pressures necessitating rapid treatment are formally diagnosed with preeclampsia with severe features []. Even without severe range blood pressures and only mild range blood pressures, patients with the following laboratory criteria are diagnosed with preeclampsia with severe features: thrombocytopenia [platelets 1.1 mg/dl], or liver impairment [liver enzymes twice the normal value] [, , ]. Lastly, patients with or without severe range blood pressures and symptoms of pulmonary edema, severe right upper quadrant pain not due to other etiologies, persistent vision changes, and new-onset headache refractory to medications may also be diagnosed with preeclampsia with severe features [, , ]. Patients with pre-existing chronic hypertension may meet the criteria for superimposed preeclampsia with severe features if they exhibit any of the laboratory abnormalities or symptoms [, , ].
A more severe form of preeclampsia known as HELLP syndrome [hemolysis, elevated liver enzymes, and low platelets] presents increasing rates of mortality and adverse maternal and fetal outcomes []. Patients demonstrate signs of hemolysis [elevated lactate dehydrogenase [LDH] > 600 IU/l], elevated liver enzymes [more than twice normal lab values], and low platelets [38 in patients with suspected preeclampsia and patients diagnosed with preeclampsia without severe features while in triage was predictive of the development of preeclampsia with severe features within 2 weeks of presentation [OR 15.6%, confidence interval 8.91–27.40 for restrictive diagnosis, and OR 14.56% with 95% confidence interval 8.30–25.56 for broader diagnosis] []. Similarly, another large study assessed the value of sFlt-1/PlGF in predicting progression to preeclampsia with severe features and identifying those at the highest risk of adverse maternal outcomes []. In patients between gestational ages of 23 and 35 weeks, a ratio of >40 [PPV 65% [95% CI 59, 71] and NPV 95% [95% CI 93, 98]] similarly showed an increased risk in progression to severe disease, but also an increased risk in adverse maternal outcomes []. Blood pressures alone in the antepartum and intrapartum period have a poor positive predictive value [PPV] for the accurate prediction of adverse outcomes [PPV 18–20% with antepartum and intrapartum blood pressures and 22–36% with antepartum blood pressures alone] []. The development of machine-based learning models has also shown promise in identifying early- and late-onset preeclampsia as well as those at the highest risk of adverse outcomes []; however, it is not readily available for clinical use. The integration of early screening for preeclampsia and biomarker use to aid in the determination of those at the highest risk of disease progression and adverse outcomes is becoming an important tool to improve the healthcare of pregnant persons suffering from preeclampsia.
5.2. Postpartum
Patients in the postpartum period remain at risk for development of HDP in the postpartum period and long-term sequelae related to a prior diagnosis of preeclampsia. In the postpartum period, there are tools that exist to aid in minimizing these adverse outcomes. Studies have illustrated that postpartum blood pressure monitoring in patients with chronic hypertension and HDP is a sustainable and important intervention for patients in the postpartum setting [, ]. One tertiary care center implemented a postpartum blood pressure monitoring program that included standardized education and assisted follow-up, illustrating a dramatic increase in postpartum visit attendance [33.5% vs. 59.4%, p < 0.001] with more patients reporting blood pressures of