Basics
Description
- Hypertension is the most common medical problem seen in pregnancy.
- Its management requires familiarity with:
- Treatment goals
- Preferred agents
- Screening for superimposed preeclampsia
- An important general guideline for the diagnosis and management of hypertension in pregnancy is as follows:
- Hypertension occurring prior to 20 weeks gestation is almost certainly chronic hypertension.
- Elevations in blood pressure that occur after 20 weeks gestation should raise suspicion of the diagnosis of preeclampsia.
Epidemiology
Incidence
Chronic hypertension complicates 5% of pregnancies.
Risk Factors
- Unchanged from the nonpregnant population
- Chronic hypertension is more common among older women, the obese, and African Americans.
Genetics
Chronic hypertension is believed to be polygenic in origin with penetrance being greatly affected by lifestyle.
General Prevention
Although there is little research in this area, strategies to prevent chronic hypertension in nonpregnant patients are likely also effective in pregnant patients.
- Exercise
- An appropriate diet
- Maintaining an ideal, but pregnancy-appropriate weight
Pathophysiology
The pathophysiology of chronic hypertension in pregnancy is unchanged from that in nonpregnant patients.
- Blood pressure typically decreases in the first 2 trimesters of pregnancy by 10 " 15 mm Hg.
- Therefore, many women with chronic hypertension may have improvement of their blood pressure early in pregnancy only to see it rise again in the third trimester.
Etiology
- The etiology of chronic hypertension is heterogeneous and remains poorly described.
- Consider secondary causes of hypertension in all patients with new onset or difficult to control hypertension:
- Endocrine causes
- Diabetes, thyroid and parathyroid disease, pheochromocytoma, hyperaldosteronism
- Renal causes
- Intrinsic renal disease
- Renovascular disease
- Medications/drug use
- Alcohol
- Coarctation of the aorta
- Sleep apnea
Associated Conditions
Approximately 20 " 25% of the patients with chronic hypertension will develop superimposed preeclampsia.
Diagnosis
- Chronic hypertension in pregnancy that is not severe and is not associated with superimposed preeclampsia is managed as an outpatient.
- Chronic hypertension is defined as BP >140/90 and is generally asymptomatic.
- Because blood pressure normally decreases in the first 2 trimesters by 10 " 15 mm Hg, a BP >130/80 in the second trimester is suggestive of underlying chronic hypertension being masked by pregnancy.
- Blood pressure should be measured manually with an appropriate sized cuff, with the patient in the sitting position, and the brachial artery at the level of the heart.
History
Evaluate patient for evidence of:
- Secondary causes of hypertension, particularly if the diagnosis is new (see "Hypertension " chapter)
- Renovascular hypertension is the most common secondary cause in this age group.
- Pheochromocytoma is the most dangerous.
- Superimposed preeclampsia in all patients >20 weeks gestation (i.e., headache, visual phenomena, epigastric or right upper quadrant pain)
Physical Exam
Evaluate patient for evidence of:
- Secondary causes of hypertension in patients not previously identified as having chronic hypertension
- Superimposed preeclampsia in all patients >20 weeks gestation (i.e., worsening hypertension, retinal vasospasm, evidence of pulmonary edema, epigastric tenderness, clonus)
Evidence of preeclampsia should lead to a prompt referral to an obstetric provider as preeclampsia is a complex disorder with both maternal and fetal complications.
Tests
Lab
- Initial evaluation of chronic hypertension in pregnancy should include a work-up of secondary causes of hypertension:
- CBC, potassium, creatinine, urinalysis, calcium, TSH, EKG
- Many providers also obtain "baseline preeclampsia labs " during the first half of pregnancy for comparison later in the pregnancy should blood pressure begin to rise.
- CBC, creatinine, uric acid, AST, and a 24-hour urine for protein
Imaging
Women with chronic hypertension in pregnancy
- Should receive an early ultrasound to confirm dating
- Often undergo additional fetal testing in the third trimester to evaluate fetal well-being:
- Serial ultrasounds for growth and
- Regular fetal "nonstress tests " or biophysical profiles
- Measurement of umbilical artery flow
Differential Diagnosis
- Improper blood pressure measurement technique
- Secondary hypertension (see "Etiology " )
- White coat hypertension
- Preeclampsia
Treatment
Chronic hypertension in pregnancy is managed as an outpatient unless severe, symptomatic, or there is evidence for superimposed preeclampsia.
Medication
- It is important for clinicians to note that one option for treatment of chronic hypertension in pregnancy is to discontinue medication and only treat if blood pressure rises above 160/100. Because blood pressure often decreases in the first 2 trimesters, many women do well with this option.
- The only antihypertensive agents that are known to be harmful to the developing fetus are ACE inhibitors and angiotensin receptor blockers (ARBs). However, published data about the other available agents are limited.
First Line
If treatment with medication is deemed desirable:
- Labetalol (starting at 100 mg b.i.d. to a maximum of 800 mg q8h)
- Methyldopa (250 mg b.i.d. to a maximum of 3,000 mg given t.i.d. to q.i.d.)
- The best safety data are available for these 2 agents; therefore, they are the preferred antihypertensive agents in pregnancy.
Second Line
- Nifedipine, pindolol, and acebutolol are all reasonable second-line choices.
- Other agents, such as HCTZ, other calcium channel blockers (aside from nifedipine), clonidine, and prazosin, are not known to be harmful in pregnancy but should be considered third-line agents.
- ACE inhibitors and likely ARBs are toxic to the fetus, and should be stopped prior to conception.
Additional Treatment
General Measures
- All experts agree that BP >160/100 due to chronic hypertension in pregnancy warrants treatment with antihypertensive medications (1)[B].
- Some experts advocate treatment for BP >140/90, whereas others would not treat until the BP is >160/100 unless "target organ " damage present. No evidence exists that treatment of BP <160/100 confers a short-term benefit to the mother or fetus (1)[B].
- Patients with BP >170 " 180/105 " 110 (opinions differ as to the exact number) require:
- Urgent evaluation for "target organ " damage
- Urgent treatment of blood pressure
- Gestational age appropriate assessment of fetal well-being
- BP <170 " 180/105 " 110 but >160/100 also requires medical treatment, but not necessarily immediate lowering if mother is asymptomatic and fetus has reassuring fetal testing.
- BP >140/90
- Requires consideration of preeclampsia if occurring after 20 weeks gestation
- Does not necessarily require medication
- Some experts treat all BP >140/90 in pregnancy whereas others treat BP >160/100.
- On every encounter after 20 weeks gestation, women should be evaluated for signs and symptoms of preeclampsia.
- Particularly true if BP >140/90
- If any signs or symptoms of preeclampsia are identified, laboratory testing for preeclampsia should be obtained (see "Preeclampsia " chapter).
- Evidence of preeclampsia will generally necessitate admission to hospital.
Issues for Referral
- Chronic hypertension in pregnancy should be co-managed with an obstetrician experienced with this condition or a maternal fetal medicine specialist.
- Secondary causes of hypertension in pregnancy should also be referred to the relevant specialist.
Complementary and Alternative Medicine
No alternative or complementary medications have been shown to affect outcomes related to hypertension in pregnancy.
Surgery
- There is no role for surgery in the treatment of primary hypertension in pregnancy.
- Chronic hypertension is not an indication for cesarean delivery.
- Surgical treatment for secondary causes of hypertension, such as thyrotoxicosis, hyperparathyroidism, and pheochromocytoma, can and should be carried out in pregnancy when indicated.
In-Patient Considerations
Admission Criteria
Pregnant women with chronic hypertension should generally be admitted to the hospital if their BP is >170/105 or if there is clinical or laboratory evidence of preeclampsia.
Discharge Criteria
- Chronic hypertension can be managed as an outpatient if preeclampsia has been confidently ruled out and BP is <160/100.
- Patients with suspected superimposed preeclampsia should generally be managed as an inpatient until delivery.
Ongoing Care
Follow-Up Recommendations
Breastfeeding
- Patients with hypertension may breastfeed.
- No antihypertensive agents are known to be harmful for breastfeeding, but sparse data about safety of agents in breastfeeding exist.
- Methyldopa, labetalol, nifedipine, acebutolol, HCTZ, enalapril, captopril, and metoprolol are all compatible with breastfeeding per the American Academy of Pediatrics.
- Atenolol and propranolol are concentrated in breast milk and should probably be avoided in breastfeeding mothers.
Patient Monitoring
- Monitor blood pressure every month for the first 32 weeks of pregnancy, every 2 weeks until 36 weeks, and then every week.
- Each visit after 20 weeks gestation should include a history and physical looking for evidence of superimposed preeclampsia.
- Obstetric providers will often do additional weekly fetal testing after 32 " 34 weeks.
Diet
- Research has not demonstrated any benefits of dietary restrictions on the management of hypertension in pregnancy.
- A diet rich in whole grains, fruits, and vegetables and low in fats and sodium is advisable for pregnant and nonpregnant women with hypertension.
Prognosis
- Prognosis is excellent for women with mild-to-moderate hypertension in pregnancy as long as they do not develop superimposed preeclampsia.
- Uncontrolled severe hypertension represents a risk both to mother and fetus.
Complications
- Chronic hypertension is associated with a slight increased risk of placental abruption, miscarriage, and intrauterine fetal demise.
- Approximately 20 " 25% of women with chronic hypertension will develop superimposed preeclampsia and may develop any of the complications associated with the disorder (see "Preeclampsia " chapter).
References
1Magee LA, Helewa M, Moutquin J-M. Diagnosis, evaluation and management of the hypertensive disorders of pregnancy. J Obstet Gynecol Canada. 2008;30:S1 " S48. Available at http://www.sogc.org/guidelines/documents/gui206CPG083_001.pdf
Additional Reading
1Podymow T, August P. Update on the use of antihypertensive drugs in pregnancy. Hypertension. 2008;51(4):960 " 969. [View Abstract]2Roberts JM, Pearson G, Cutler J. Summary of the NHLBI Working Group on research on hypertension during pregnancy. Hypertension. 2003;41:437 " 445. [View Abstract]3Sibai BM. Diagnosis and management of gestational hypertension and preeclampsia. Obstet Gynecol. 2003;102:181 " 192. [View Abstract]
Codes
ICD9
- 642.20 Other pre-existing hypertension complicating pregnancy, childbirth, and the puerperium, unspecified as to episode of care or not applicable
- 642.23 Other pre-existing hypertension, complicating pregnancy, childbirth, and the puerperium, antepartum condition or complication
- 642.93 Unspecified hypertension complicating pregnancy, childbirth, or the puerperium, antepartum condition or complication
- 642.73 Pre-eclampsia or eclampsia superimposed on pre-existing hypertension, antepartum condition or complication
- 642.70 Pre-eclampsia or eclampsia superimposed on pre-existing hypertension, unspecified as to episode of care or not applicable
- 642.90 Unspecified hypertension complicating pregnancy, childbirth, or the puerperium, unspecified as to episode of care or not applicable
ICD10
- O10.019 Pre-existing essential htn comp pregnancy, unsp trimester
- O10.919 Unsp pre-existing htn comp pregnancy, unsp trimester
- O11.9 Pre-existing hypertension with pre-eclampsia, unsp trimester
- O10.419 Pre-existing secondary htn comp pregnancy, unsp trimester
SNOMED
- 199005000 pre-existing hypertension complicating pregnancy, childbirth and puerperium (disorder)
- 67359005 pre-eclampsia added to pre-existing hypertension (disorder)
- 86041002 pre-existing hypertension in obstetric context (disorder)
- 78808002 essential hypertension complicating AND/OR reason for care during pregnancy (disorder)
- 199008003 pre-existing secondary hypertension complicating pregnancy, childbirth and puerperium (disorder)
Clinical Pearls
- Most women with chronic hypertension in pregnancy can expect good pregnancy outcomes.
- The main risk of chronic hypertension in pregnancy is that of superimposed preeclampsia.
- Methyldopa and labetalol are the preferred agents for treatment of chronic hypertension in pregnancy.
- Opinion varies as to whether the target blood pressure for hypertension control in pregnancy is <160/100 or <140/90. Both approaches are acceptable.