According to research, ACE (Angiotensin converting enzyme), ARBs (Angiotensin II receptor blockers), and renin inhibitors causes fetal renal damage during pregnancy (Moretti et.al. 2012). ACE is extensively prescribed as a first-line drug in hypertensive patients who are non-pregnant. Besides, ARBs are also gaining popularity for their use in treating hypertension. However, the two classes of drugs have contraindications because they cause severe effects on the fetus, especially when used beyond the first trimester of pregnancy. Current evidence shows that the drugs cause renal insufficiency and fetal hypotension.
The etiology of these disorders has a close relationship to fetal hypotension and reduced renal blood flow in the zygote. Other side effects of these drugs among pregnant patients include prematurity, adverse neonatal hypotension, fetal death, intrauterine growth restriction, patent ductus arteriosus, and neonatal anuria. Oligohydramnios-associated anuria results in pulmonary hypoplasia, craniofacial deformities, and fetal limb contractures (Moretti et.al. 2012). Therefore, ACE, ARBs, and renin inhibitors should not be prescribed to pregnant patients due to their adverse effects.
Several studies have pointed to labetalol as a peripheral vasodilator which has proved useful in treating pre-eclamptic and non-proteinuric hypertension in pregnant women. Available evidence proves that the drug does not compromise uterine or renal blood flow. In an RCT (randomized control trial) conducted on 263 women living with hypertension, labetalol or methyldopa therapies led to a significant reduction in maternal blood pressure throughout the gestation as compared with no medication (Weihua et.al, 2015). Oral calcium antagonists have proved effective in controlling maternal blood pressure when administered to pregnant women suffering from mild to moderate hypertension, especially when used in the late stages of pregnancy. The calcium channel blockers work best in expectant mothers with pre-eclampsia and show no signs of severe perinatal or fetal effects. Nifedipine is among one of the best calcium channel blockers and has been proven to be effective when used in the later stages of pregnancy (Weihua et.al, 2015).
Moretti, M. E., Caprara, D., Drehuta, I., Yeung, E., Cheung, S., Federico, L., & Koren, G. (2012). The fetal safety of angiotensin converting enzyme inhibitors and angiotensin II receptor blockers. Obstetrics and gynecology international, 2012.
Weihua, L., Qing, G., Xiaoyan, Y., & Zhu, J. (2015). Antihypertensive Drug Therapy for Mild-to-Moderate Hypertension during Pregnancy: Summaries of Nursing Care-Related Systematic Reviews from the Cochrane Library. Journal of Cardiovascular Nursing, 30(1), 13-14.