When do you treat chronic hypertension in pregnancy?

The American Congress of Obstetricians and Gynecologists (ACOG) recommends that women with chronic hypertension (CHTN)  with no evidence of end organ damage (such as kidney disease) do not need treatment with pharmacologic antihypertensive therapy if their systolic blood pressure (SBP) is less than 160 mm Hg systolic or their diastolic blood pressure (DBP) is less  than 105 mm Hg .

Women with CHTN who have a SBP of 160 mm Hg or higher or DBP of 105 mm Hg or higher , OR  women with CHTN with evidence of end organ damage should be treated to maintain SBP between 120 and 160 mm Hg and DBP between 80 to 105 mm hg.
 

REFERENCE

Hypertension in pregnancy: executive summary. Obstet Gynecol. 2013 Nov;122(5):1122-31. doi:10.1097/01.AOG.0000437382.03963.88.PMID:24150027