Which antihypertensive treatment is better for mild to moderate hypertension in pregnancy?

Dear Editor,

Certainties: Treatment for brachial and ankle hypertension in pregnancy

Ashworth et al highlight the lack of evidence and uncertainties for the effectiveness of drugs to treat mild to moderate hypertension in pregnancy on clinical outcomes such as stroke or perinatal death [BMJ 2022; 376 doi: https://doi.org/10.1136/bmj-2021-066333 (Published 18 January 2022)].

Overall, most experts agree the pathophysiology of hypertension in pregnancy is multifactorial [1]. Maternal sequelae of gestational hypertension, pre-eclampsia, and eclampsia resolve rapidly after delivery therefore it proves that pathophysiology is related to placenta. Antiangiogenic factors that are released by placental tissue cause systemic endothelial dysfunction and there is improper trophoblast differentiation. However, for lone chronic hypertension one of the factors in pathophysiology is insulin resistance [2]. Insulin resistance is present in normal pregnancy however, if pathological then management with lifestyle and specific insulin sensitizers e.g., metformin becomes important for treatment of chronic hypertension in pregnancy. Metformin is recommended in pregnancy for gestational diabetes mellitus anyway and therefore is safe [3].

Another issue to emphasize is that ankle blood pressures are associated with type 2 diabetes (pathological insulin resistance) more than the brachial blood pressures in non-pregnant primary care populations [4]. Although pathophysiology of brachial and ankle hypertension might be similar the role of insulin resistance might be even more for ankle hypertension especially in pregnancy and in non-European ethnic groups e.g., south Asians and Afro-Caribbeans [4]. It will be interesting to conduct research to study the range and variation in ankle blood pressures between normal pregnancies and ones with chronic hypertension, gestational hypertension, pre-eclampsia, and eclampsia. Trials of specific insulin sensitizers versus standard antihypertensive treatments in pregnancy complicated by brachial and ankle hypertension in different ethnic groups are vital to create certainties for management of different types of hypertensions in pregnancy.

Sincerely,

Dr Kirti Kain MDFRCP FHEA, Dr. Hema Viswambharan Ph.D., FHEA (University of Leeds), Dr. Chew Weng Cheng Ph.D (University of Leeds).

References
1 Yang, Y. Y. et al. A retrospective cohort study of risk factors and pregnancy outcomes in 14,014 Chinese pregnant women. Medicine (Baltimore) 97, e11748, doi:10.1097/MD.0000000000011748 (2018).
2 Beevers, G., Lip, G. Y. & O'Brien, E. ABC of hypertension: The pathophysiology of hypertension. BMJ 322, 912-916, doi:10.1136/bmj.322.7291.912 (2001).
3 Rowan, J. A. et al. Metformin versus insulin for the treatment of gestational diabetes. N Engl J Med 358, 2003-2015, doi:10.1056/NEJMoa0707193 (2008).
4 Viswambharan, H., Cheng, C. W. & Kain, K. Differential associations of ankle and brachial blood pressures with diabetes and cardiovascular diseases: cross-sectional study. Sci Rep 11, 9406, doi:10.1038/s41598-021-88973-3 (2021).