Hypertensive Disorders of Pregnancy
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Accurate blood pressure (BP) measurement aids early detection of hypertensive disorders that may lead to eclamptic seizures or stroke (Box 1).
Treatment is indicated for systolic BP of 160 mm Hg or greater, diastolic BP of 110 mm Hg or greater, or both, confirmed as persistent (lasting 15 minutes or more).undefined#ref1">1,2
Administer antihypertensive treatment, as ordered, as soon as possible, but ideally within 60 minutes after criteria are met.1,2
Several types of hypertensions can occur in pregnancy (Table 1):1,2,5,7
Hypertension in pregnancy is categorized according to BP, proteinuria, the onset of symptoms related to gestation, and system involvement (Table 1).1,2 Establishing a patient baseline and conducting regular assessments of vital signs, symptoms, and laboratory results is essential to identifying hypertensive disorders of pregnancy.2
Gestational hypertension occurs when patients have abnormal BP values after 20 weeks’ gestation.1,2 It is considered severe when the systolic BP reaches or exceeds 160 mm Hg or the diastolic BP reaches or exceeds 110 mm Hg.1,2 Proteinuria and other symptoms of preeclampsia are absent in gestational hypertension; however, it is common for gestational hypertension to progress to preeclampsia.2
Preeclampsia affects 2% to 8% of patients who are pregnant and is a major cause of perinatal morbidity and mortality worldwide.2 When hypertension progresses to preeclampsia, patients are at risk for seizures.2 Patients who are pregnant with chronic hypertension or preeclampsia have an increased risk of stroke or cerebral complications during pregnancy, even without excessive elevations in BP.1
Risk factors for developing preeclampsia include (Box 2):2
Relying on patient symptoms can be problematic when diagnosing preeclampsia because symptoms can be nonspecific in nature and are not clearly indicative of hypertensive disorders of pregnancy. Preeclampsia can result in short- and long-term complications for patients who are pregnant or postpartum. Complications of preeclampsia include:2
Generalized pitting edema (Figure 1), once a diagnostic criterion for preeclampsia, is now a nonspecific sign.2 Pitting edema may be absent in some patients who develop preeclampsia and may be severe in other pregnant patients who do not have preeclampsia.6 Headaches are unreliable and nonspecific as a diagnosis criterion.2
A severe form of preeclampsia is hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome. HELLP syndrome has been associated with higher rates of patient morbidity and mortality and is mostly seen during the third trimester but can also present for the first time or progress during the postpartum period (Table 1).1,2 The main presenting symptoms in HELLP syndrome include right upper quadrant pain, generalized malaise, nausea, and vomiting.2
Pregnant patients with hypertension or preeclampsia have an increased risk of stroke or cerebral complications.1 Treatment is indicated for systolic BP of 160 mm Hg or greater, diastolic BP of 110 mm Hg or greater, or both, confirmed as persistent (lasting 15 minutes or more).1,2 Antihypertensive treatment should be administered as soon as possible, but ideally within 60 minutes after criteria are met.1,2 Therapeutic objectives of hypertensive treatment are to decrease the risk of congestive heart failure, myocardial ischemia, renal injury or failure, and ischemic or hemorrhagic stroke.1,2 Antihypertensive treatment in the obstetric population may be provided with first-line agents, such as nifedipine (immediate release oral) or IV labetalol or hydralazine.1,2 Continued medication treatment may include labetalol, nifedipine, hydralazine, or methyldopa.1,2 Methyldopa is not used as frequently due to side effects and lesser effectiveness when compared with labetalol, nifedipine, or hydralazine.1
Seizures related to hypertension that develop during pregnancy are called eclamptic seizures. Eclampsia is frequently preceded by signs of cerebral irritation, such as severe, persistent occipital and frontal headaches; blurred vision; photophobia; and altered mental status, but it can also occur without any warning signs or symptoms at all.2 Most eclamptic seizures are self-limited, but can cause patient hypoxia, and prolonged fetal heart rate (FHR) abnormalities. Eclamptic seizures that occur postpartum usually occur within the first 7 days, and 50% of eclamptic seizures occur in labor or within the first 48 hours postpartum.6
Magnesium sulfate is the drug of choice for preventing seizures in patients with preeclampsia with severe features and potential hypertensive crisis during the pregnancy and postpartum periods.2 Its mechanism of action for seizure prevention is unclear, but it may work as a central anticonvulsant, may prevent or decrease cerebral edema, or may cause vasodilation in the cerebral and peripheral circulation.5 Although magnesium is used for seizure prevention, it is not given to stop a seizure, but to prevent the recurrence.2
To prevent adverse maternal and fetal outcomes, delivery of the fetus is recommended when gestational hypertension or preeclampsia with severe features is diagnosed at 34 0/7 weeks gestation or beyond, after the patient is stabilized, or with labor or pre-labor rupture of membranes.2 When the late preterm period has been reached, delay of delivery to administer steroids is not recommended.2 For patients with preeclampsia without severe features or with gestational hypertension, expectant management up to 37 weeks’ gestation is recommended, along with frequent maternal and fetal evaluation.2
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If BP is greater than or equal to 140/90 mm Hg, repeat the BP measurement within 15 minutes.3
Seizure activity may occur without warning signs or symptoms in some patients.2
Rationale: Hyperreflexia, clonus, continuous headache, drowsiness, or mental confusion are signs of poor cerebral perfusion and may foreshadow seizure activity.6
Rationale: Visual disturbances, such as blurred vision or double vision, may indicate retinal edema and arterial spasms.6
Rationale: Epigastric pain, nausea, or vomiting may indicate liver capsule distention and increase the chance of liver rupture associated with severe preeclampsia.6
Rationale: Decreased urinary output is caused by poor renal perfusion and may precede acute renal failure.6
Rationale: Abdominal tenderness could indicate placental abruption in a patient with preeclampsia.6
FHR is assessed for evidence of adequate uteroplacental oxygenation. Fetal compromise may be identified during auscultation if abnormal heart tones are noted.4
Magee, L.A., Khalil, A., von Dadelszen, P. (2020). Pregnancy hypertension diagnosis and care in COVID-19 era and beyond. Ultrasound in Obstetrics & Gynecology, 56(1), 7-10. doi:10.1002/uog.22115
Society for Maternal-Fetal Medicine; Publications Committee. (2022). Society for Maternal-Fetal Medicine statement: Antihypertensive therapy for mild chronic hypertension in pregnancy–The chronic hypertension and pregnancy trial. American Journal of Obstetrics and Gynecology, 227(2), B24-B27. doi:10.1016/j.ajog.2022.04.011.
Society for Maternal-Fetal Medicine (SMFM) and others. (2022). Society for Maternal-Fetal Medicine special statement: A quality metric for evaluating timely treatment of severe hypertension. American Journal of Obstetrics and Gynecology, 226(2), B2-B9. doi:10.1016/j.ajog.2021.10.007.
Society for Maternal-Fetal Medicine (SMFM) and others. (2022). Society for Maternal-Fetal Medicine special statement: Quality metric for timely postpartum follow-up after severe hypertension. American Journal of Obstetrics and Gynecology, 227(3), B2-B8. doi:10.1016/j.ajog.2022.05.045.
US Preventive Services Task Force and others. (2021). Aspirin use to prevent preeclampsia and related morbidity and mortality: US Preventive Services Task Force recommendation statement. JAMA, 326(12), 1186-1191. doi:10.1001/jama.2021.14781.
Xydopoulos, G. and others. (2019). Home blood-pressure monitoring in a hypertensive pregnant population: Cost-minimization study. Ultrasound in Obstetrics & Gynecology, 53(4), 496-502. doi:10.1002/uog.19041
Clinical Review: Adele Clobes, JD, APRN, CNM
Published: October 2023
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