Unfortunately, hypertensive disorders of pregnancy are markedly increasing (100, 101). For instance, in the United States between 1998 and 2006, hypertensive disorders in pregnancy increased from 6.7% to 8.3%, chronic HTN in pregnancy increased from 1.1% to 1.7%, and preeclampsia/eclampsia from 0.9% to 1.2%. The potential serious consequences of HTN and pregnancy and the contraindication in pregnancy of some of the commonly prescribed pharmacological antihypertensive medications discussed below should be discussed with women who are or could become pregnant. The normal haemodynamic state of pregnancy is one of systemic vasodilation accompanied by an increase in cardiac output and decrease in total peripheral resistance. This results in a normal decrease in BP in the second trimester. HTN in pregnancy is generally diagnosed when BP is ≥140 mmHg and/or ≥90 mmHg on at least two occasions, at least six hours apart. Chronic HTN is defined as a diagnosis of HTN before 20 weeks gestation, while gestational HTN is defined as a diagnosis of HTN at 20 weeks or later. Pre-eclampsia and eclampsia are pregnancy-specific medical conditions requiring immediate and specific medical management. 22 While BP treatment thresholds for HTN in pregnancy continue to change, it is generally recommended for both chronic and gestational HTN that pharmacologic treatment be initiated when the SBP is ≥160 mmHg and/or the DBP is ≥105 mmHg. In chronic HTN, frequently the woman has already been diagnosed with HTN prior to the pregnancy and thus may already be on chronic antihypertensive pharmacological therapy. In this case, the current regimen may be continued, with the caveat that the medication regimen may have to be changed to preferred medications, and certain antihypertensive medications that are contraindicated in pregnancy must be discontinued. The recommended treatment BP goal/target also has been subject to debate and is changing. For instance, achieving a lower BP target (DBP of 85 mmHg vs 100 mmHg) has recently been shown to decrease the maternal development of severe HTN while not increasing maternal or fetal risk. If target organ damage is present, initiating antihypertensive pharmacological treatment at a DBP of ≥90 mmHg should be considered. As with most, if not all, other medical conditions requiring pharmacological treatment during pregnancy, the treatment considerations in HTN are no different from those of non-pregnant adults. Thus, since medications are not studied specifically for efficacy and safety in pregnancy, medication selection is usually based on long-term clinical use and experience. This usually means older medications that have had a substantial long-term track record of efficacy and safety are to be considered. For the pharmacological treatment of HTN in pregnancy, preferred medications include methyldopa, beta-blockers (particularly labetalol), CCBs (particularly nifedipine and, as an alternative, verapamil), and the direct-acting vasodilators (particularly hydralazine). There is evidence to suggest that among these agents, beta-blockers and CCBs appear to be more effective than methyldopa in decreasing the development of severe HTN later in the pregnancy. The use of thiazide diuretics has been debated, particularly if the individual is already chronically on a thiazide prior to the pregnancy. In this situation the thiazide diuretic may be continued during the pregnancy. There are clear contraindications to the use of some antihypertensive medications during pregnancy. These include all the renin–angiotensin system inhibitors, such as the ACEis, the ARBs and, although not used any more, the direct-acting renin inhibitors, due to direct adverse effects on the fetus, and the mineralocorticoid receptor antagonist spironolactone due to fetal anti-androgen effects. The use of the beta-blocker atenolol is also contraindicated due to the observation of intrauterine fetal growth inhibition (102). In summary, HTN in pregnancy, manifested by the various hypertensive pregnancy disorders, is a very common medical condition. HTN pregnancy disorders have serious maternal and fetal consequences. There are currently several preferred oral antihypertensive pharmacological agents available to treat chronic HTN and gestational HTN during pregnancy. In addition, there are antihypertensive pharmacological agents that are contraindicated in pregnancy. There is evidence to support the pharmacological treatment of HTN in pregnancy at given BP thresholds without and with the presence of end organ damage to decrease the likelihood of the development of severe HTN later in the pregnancy. Even with the effective lowering of BP during the pregnancy and in the immediate postpartum period, the presence of hypertensive disorders of pregnancy significantly increases long-term CV risk, including future HTN, coronary disease, and stroke. SPECIAL SETTINGS 23 GUIDELINE FOR THE PHARMACOLOGICAL TREATMENT OF HYPERTENSION IN ADULTS 5 Publication, implementation, evaluation and research gaps 5.1 Publication This guideline is available to download from the WHO website. Given that an overview of published systematic reviews was used for the development of the guideline, all reviews are already published and available online. 5.2