michigan hypertension core curriculum - State of Michigan

etween adult socioeconomic position and pregnancy induced hypertension have found
contradictory results.
4. BMI and maternal weight gain: There are few modifiable risk factors for pregnancy-related
hypertensive disorders, but body mass index (BMI) and maternal weight gain may be important
factors. A recent prospective cohort study 7 found that preconception BMI> 30 was a risk factor
for preeclampsia (OR 3.3) and severe transient hypertension (OR 8.8 in Caucasian women and
4.9 in Black women). High gestational weight gain was also a risk factor or, alternatively, was
associated with risk factors for pregnancy induced hypertension 8 and preeclampsia. 9
There is no single effective screening test that predicts preeclampsia.
Management
Evaluation and counseling of women with chronic hypertension should begin before conception
and should include screening for target organ damage (including baseline measurement of renal
function and proteinuria), and evaluation for secondary causes of hypertension. It is essential before
conception that the patient’s antihypertensive medications be reviewed and that those drugs harmful to
the developing fetus (angiotensin-converting enzyme [ACE] inhibitors, angiotensin II receptor blockers)
be discontinued and replaced with medications considered safe for use during pregnancy (methyldopa,
labetalol).
It has to be recognized from the outset that the selection of a particular drugs to treat
hypertension during pregnancy is all opinion based except for the avoidance of a small number of drugs
known to be harmful to the fetus (e.g., ACEIs and ARBs as noted above). Only a few antihypertensive
medications are recognized as being safe for use in pregnancy. No antihypertensive medication has
specifically been proven safe for use during the first trimester It is exceeding difficult for ethical reasons
to conduct randomized controlled trials during pregnancy. A recent Cochrane review 10 was only able
to conclude “Until better evidence is available, the choice of antihypertensive should depend on the
clinician’s experience and familiarity with a particular drug, and on what is known about adverse
effects. Exceptions are diazoxide, ketanserin, nimodipine and magnesium sulphate, which are probably
best avoided.” The reader is also referred to recent comprehensive reviews on the management of
hypertensive disorders during pregnancy 11-13
Gestational vasodilation frequently allows the discontinuation of most or all antihypertensive
medications early in pregnancy, although some may need to be restarted closer to delivery. Although
bed rest is recommended for women with hypertension and preeclampsia, there is no evidence to show
that it improves outcomes of pregnancy.
There is no evidence from controlled trials that antihypertensive drugs improve maternal
or fetal outcome in mild to moderate hypertension (BP< 160/110), whether pregnancy-induced or
chronic. Not surprisingly, guidelines vary as to recommended thresholds for initiating antihypertensive
medications. The most recent US guidelines advise treatment at ≥ 160/105 3 . Severe hypertension (≥
160/110 requires prompt treatment to reduce the risk of maternal intracerebral hemorrhage or death.
It is important that the obstetrical service or obstetrician be involved in women with a gestational age
beyond 24 weeks to assist in antihypertensive management decisions that may affect the fetal status,
as well as decide if or when emergent delivery is indicated.
262 Hypertension Core Curriculum