Definitions and Diagnosis
Chronic hypertension in pregnancy is defined as hypertension diagnosed or present before this gestational age
20w0d
At the initial evaluation of chronic hypertension in pregnancy, this lab abnormality—if present at baseline—complicates the later diagnosis of superimposed preeclampsia.
Preexisting proteinuria
The CHAP trial demonstrated improved outcomes when antihypertensive therapy was initiated at or above this lower blood pressure threshold in mild chronic hypertension.
140/90
In addition to chronic hypertension itself, the presence of this condition further increases the indication strength for low-dose aspirin prophylaxis
Any other high risk factor for PEC
- diabetes
- renal disease
- autoimmune disease
38w0d – 39w6d
This physiologic change in early pregnancy can mask chronic hypertension, sometimes delaying diagnosis until later gestation
In diagnostic uncertainty, this new hematologic abnormality may help point toward superimposed preeclampsia rather than worsening chronic hypertension
New thrombocytopenia
The primary composite outcome improved in CHAP included preeclampsia with severe features, medically indicated preterm birth <35 weeks, placental abruption, or this fetal outcome
Fetal or neonatal death
Low-dose aspirin reduces preeclampsia risk primarily through effects on this placental pathophysiologic process
Abnormal placentation and impaired trophoblastic invasion (which leads to uteroplacental insufficiency)
cHTN, well controlled, on meds
37w0d – 39w6d
Chronic hypertension is defined not only by diagnosis before 20 weeks, but also by persistence of elevated blood pressure beyond this postpartum time frame
12 weeks
In diagnostic uncertainty, what is the most important lab collection to help distinguish between a chronic hypertension exacerbation and new superimposed preeclampsia with severe features?
24 hour urine collection
According to CHAP, treating mild chronic hypertension to a target below 140/90 mm Hg did NOT increase the risk of this fetal complication
Fetal growth restriction
Even with improved blood pressure control, what fetal surveillance strategy remains recommended due to persistent baseline risk in chronic hypertension
serial growth ultrasounds in the 3rd trimester
cHTN, poorly controlled, requiring frequent medication adjustments
36w0d – 37w6d
In patients with known chronic hypertension, this pattern of blood pressure change later in pregnancy should raise concern for superimposed preeclampsia rather than physiologic variation
Sudden worsening or escalation in previously stable blood pressures
superimposed preeclampsia carries significantly higher risks for: preterm delivery (OR 2.79), placental dysfunction including severe preeclampsia/abruption/oligohydramnios/SGA (OR 2.23), perinatal mortality (OR 1.79), cesarean delivery, and NICU admission
For pregnant patients treated with antihypertensives, the recommended maintenance blood pressure range is ABOVE this lower limit
120/80
The greatest reduction in preeclampsia risk with low-dose aspirin is seen when it is initiated before this gestational age
before 16 weeks
cHTN with superimposed preeclampsia with severe features
34w0d or at diagnosis if later
What are the most common antihypertensive medications used in pregnancy, and their max dosages?
Labetalol, 2400mg max daily oral, 300mg IV
Nifedipine, 120mg XR max daily, 180mg IR
In a patient with chronic hypertension who develops severe-range blood pressures but no clear laboratory abnormalities, what management principle helps distinguish transient worsening from superimposed preeclampsia with severe features?
Confirmation of persistent severe-range blood pressures (≥160/110) over minutes to hours requiring treatment, often with inpatient observation and serial assessment
Name two medication classes or agents the bulletin says are generally not recommended for chronic antihypertensive treatment in pregnancy
ACE inhibitors
ARBs
Renin inhibitors
Mineralocorticoid receptor antagonists
Why is it not recommended for all pregnant patients to take aspirin?
very low risk patients have minimal benefit with aspirin
cHTN with siPEC with SF, with unstable maternal or fetal status
Soon after maternal stabilization