Case Study: Treating Chronic Hypertension in Pregnancy

Case: A 35-year-old female presents to clinic. She is actively trying for pregnancy and already stopped her birth control. Her medical history includes a 5-year history of hypertension treated with an ACE inhibitor.

Today her blood pressure is 124/68 mmHg and BMI 27 kg/ m². What recommendations do you have for management of this patient’s situation?

Chronic hypertension in pregnancy is defined as >140/90mmHg.¹ The prevalence of hypertension in pregnant women is estimated to be around 3%, with potential association with women having children at a later age.⁴

Chronic hypertension during pregnancy increases the risk of poor pregnancy and birth outcomes.^3,4 Although consensus exists to use antihypertensive therapy to treat severe hypertension (systolic ≥160, diastolic ≥105-110 mmHg) during pregnancy, the benefits and safety for treating mild chronic hypertension during pregnancy are unclear.

According to the American College of Obstetricians and Gynecologists’ Task Force on Hypertension in Pregnancy, the controversy in mild to chronic hypertension in pregnancy is due to the lack of evidence to guide therapy.¹

Methyldopa, a centrally acting alpha agonist has traditionally been first line for hypertension in pregnancy.³ But a common adverse effect (AE) of methyldopa is somnolence.

Drs Seely and Ecker, authors of “Chronic Hypertension in Pregnancy” recommend labetalol. Labetalol, a combined alpha and beta blocker, has fewer AEs than methyldopa.³ A common AE of labetalol is dizziness.²

Nifedipine, a long-acting calcium channel blocker, was also an alternative antihypertensive drug.^3,4 ACEis/ARBs are contraindicated because they cause oligohydramnios from impaired fetal growth.³

The Chronic Hypertension and Pregnancy (CHAP) trial looked at treatment of mild chronic hypertension in pregnancy. This multi center, open label, randomized, controlled trial enrolled 2408 women with mild chronic hypertension and singleton fetus at <23 weeks’ gestation.

The active treatment group had 1202 women and wanted to achieve a systolic blood pressure <140/<90mmHg. The standard treatment group, also 1202 women, received no treatment unless severe hypertension developed ≥160/≥105 mmHg.

The active treatment group received labetalol or extended release nifedipine, or other drugs such as amlodipine or methyldopa by preference.⁴ Doses were escalated to the maximum dose to achieve the target blood pressure.

The primary outcome was a composite of preeclampsia with severe features, medically indicated preterm birth before 35 weeks, placental abruption, or fetal or neonatal death. The active treatment group’s primary outcome was significantly lower than standard treatment, with an approximate incidence of 30.2% versus 37.0%.⁴

The safety outcome of the incidence was small for gestational age birth weight below the 10th percentile and did not differ significantly between the active treatment group and standard treatment group.⁴ In an analysis of secondary outcomes, composites of serious maternal complications or serious neonatal complications occurred infrequently.

The results suggest lower rates of pre-eclampsia and preterm birth with antihypertensive therapy.⁴ Some limitations were that women were aware of their treatment, there was a high ratio of women screened to women enrolled, and this trial was not powered to see treatment effects across subgroups. The authors conclude that treating mild chronic hypertension during pregnancy reduced adverse pregnancy outcomes without impairing fetal growth.⁴

Based on this information, the patient in our case should be counseled on contraception until she has her pre-pregnancy evaluation. If she has a reversible cause of chronic hypertension, that should be addressed along with changing her ACE inhibitor to a drug that is safe in pregnancy such as methyldopa, labetalol, or nifedipine. She should also be closely followed during her pregnancy, receive interdisciplinary care from obstetrics and gynecology practitioners, and be educated on pre-eclampsia.

About the Author

Momi Talukdar, PharmD candidate, Northeast Ohio Medical University, Class of 2024, 2022 Mayo Clinic pharmacy intern.

References

1. Hypertension in Pregnancy. American College of Obstetricians and Gynecologists. 2013;122(5):1122-1133. Accessed June 27, 2022. https://oce.ovid.com/article/00006250-201311000-00036/PDF
2. Labetalol. Lexi-Drugs. Lexicomp. Wolters Kluwer Health. Inc. Riverwoods, IL. Available at: http://online.lexi.com. Accessed July 3, 2022
3. Seely,E., Ecker, J. 2011. Chronic Hypertension in Pregnancy | NEJM. [online] New England Journal of Medicine. Available at: <https://www/nejm.org/doi/full/10.1056/NEJMcp0804872> [Accessed 27 June 2022].
4. Tita, A., Szychowski, J. and Boggess, K., 2022. Treatment for Mild Chronic Hypertension during Pregnancy | NEJM. [online] New England Journal of Medicine. Available at: <https://www.nejm.org/doi/full/10.1056/NEJMoa2201295> [Accessed 24 June 2022].