Managing Preeclampsia and High Blood Pressure During Pregnancy
Preeclampsia (high blood pressure during pregnancy) can have harmful effects if not properly treated. Doctors should inform mothers of the risks of high blood pressure on the baby as soon as the mother is diagnosed, and provide a plan to help control high blood pressure. This plan is personalized depending on the mother’s medical history. Sometimes this may be a combination of diet and exercise; in other cases, blood pressure medication may be need. Often, mothers with high blood pressure during pregnancy are referred to a maternal-fetal medicine specialist (MFM), an obstetrician that focuses specifically on high-risk pregnancy.
Why is it Important for Caregivers to Manage Preeclampsia During Pregnancy?
Preeclampsia is a condition that poses health risks to both mother and baby. For the mother, uncontrolled preeclampsia can become HELLP syndrome, hypertensive crisis, or eclampsia or stroke during labor. This means the mother may have seizures or kidney failure, which is very serious. For the baby, in addition to the risks of eclampsia, preeclampsia can compromise blood supply through the placenta. This is linked to numerous health complications and injuries, such as:
- Intrauterine (fetal) growth restriction (IUGR) (a baby that isn’t growing enough due to insufficient nutrient delivery)
- Hypoxic ischemic encephalopathy (HIE) due to insufficient oxygen supply through the placenta, which can in turn cause cerebral palsy (CP), seizure disorders, intellectual disabilities, developmental delays, motor disorders, and microcephaly.
- Periventricular leukomalacia (PVL)
- Premature birth and placental abruption
Proper treatment and management of preeclampsia helps reduce the risk of injury due to preeclampsia for both the mother and the baby.
How is High Blood Pressure Managed During Pregnancy?
Obstetricians and MFMs manage pregnancy in several ways. These may include (but aren’t limited to):
- Advising the mother about diet and exercise-related interventions to help control preeclampsia
- Properly prescribing blood pressure medication to the mother.
- Closely monitoring the mother and baby throughout pregnancy, labor and delivery for signs of complications
- Developing a plan for early delivery to avoid injury due to health issues stemming from preeclampsia
Understanding the Different Types of Blood Pressure Disorders During Pregnancy
Normal blood pressure is 120/80 mmHg. The top number is the systolic blood pressure (BP) and the bottom number refers to diastolic BP.
There are multiple kinds of high blood pressure disorders that can occur during pregnancy. Your doctor should identify what kind of high blood pressure you have developed, as this may impact the kind of treatment they prescribe:
- Long-term high blood pressure. When a pregnant woman has long-term high blood pressure, it is called chronic (preexisting) hypertension. A mother is diagnosed with chronic hypertension when her systolic BP was ≥140 and/or diastolic BP was ≥ 90 before becoming pregnant, or these high BP numbers are present before the 20th week of pregnancy. Chronic hypertension is also diagnosed when these elevated BP numbers persist longer than 12 weeks after delivery.
- Gestational hypertension. A pregnant woman is diagnosed with gestational hypertension when high BP is first detected after 20 weeks of pregnancy and there is no protein in the urine (proteinuria) or other indications of preeclampsia. Some mothers with gestational hypertension may develop end-organ dysfunction or proteinuria and may then be considered preeclamptic, while other mothers will be diagnosed with preexisting hypertension due to persistent high blood pressure after delivery.
- Preeclampsia and eclampsia. Preeclampsia refers to high blood pressure newly diagnosed during pregnancy and either proteinuria or end-organ dysfunction. Preeclampsia is typically diagnosed after 20 weeks of gestation in a mother who previously had normal BP. Eclampsia is diagnosed when a mother has preeclampsia and seizures.
- Preeclampsia-eclampsia superimposed upon chronic hypertension. This condition is diagnosed when a pregnant woman with chronic hypertension develops worsening high BP with a new diagnosis of proteinuria or other features of preeclampsia.
Decision-Making Regarding High Blood Pressure During Pregnancy
Both risks and benefits should be considered when treating for high blood pressure during pregnancy. The most important factor is how high the mother’s BP is. Treatment of severely high BP (systolic ≥ 160 and/or diastolic ≥ 110) reduces the risk of stroke in the mother. Maternal stroke can cause the baby to have birth injuries.
Another factor to consider when treating high BP and preeclampsia is the cause of the high BP. Mothers with chronic hypertension, for example, may be able to tolerate higher blood pressures better than mothers who previously had normal blood pressure with a sudden onset of high BP caused by preeclampsia.
The decision regarding when to deliver the baby is important for a number of reasons. If a prompt C-section delivery is planned, medications for high BP may not be needed since anesthesia and/or magnesium sulfate may lower blood pressure.
Who is Treated with Medication for High Blood Pressure During Pregnancy?
The decision to use medication to treat mothers who have mild hypertension (140 – 150 systolic BP and 90 – 100 diastolic BP) or moderate hypertension (150 – 159 systolic BP and 100 – 109 diastolic BP) requires very skillful assessment and close monitoring of the mother and baby. In some cases, aggressive lowering of the mother’s BP – and the drugs themselves – can cause poor fetal growth and can expose the baby to the harmful effects of the medications. The mother’s physician should consider the entirety of the mother’s medical history as well as her symptoms when making treatment decisions for mild to moderate hypertension. Pregnant women who have hypertension or preeclampsia should have a target BP of 140 – 150 systolic and 90 – 100 diastolic. When end-organ damage is present, the target BP is 140/90 or as low as 120/80.
- Although the risks to the unborn baby often outweigh the benefits of using antihypertensive medications to treat mild to moderate hypertension, severe hypertension must always be treated. Treatment should be given to mothers whose systolic pressure is 150 or higher or whose diastolic pressure is 100 or higher.
- Medication should be given at a lower threshold to younger pregnant women whose BP is lower or who had a lower baseline BP.
- Mothers who have symptoms that may be caused by high BP such as headache, visual disturbances, or chest discomfort) should be treated.
Types of Medications for Treating High Blood Pressure During Pregnancy
Medications used to treat high BP are called antihypertensive drugs. These drugs cross the placenta. Common antihypertensive medications given during pregnancy include:
- Calcium channel blockers (e.g., nifedipine and labetalol)
- Thiazide diuretics
Certain antihypertensive drugs injury to the baby and should be avoided. These include:
- ACE inhibitors (angiotensin converting enzyme inhibitors)
- ARBs (angiotensin II receptor blockers)
- Direct renin inhibitors
Methyldopa or labetalol are usually the drugs of choice for treatment of high BP, with nifedipine added if needed. When a pregnant woman has sudden onset hypertension, IV labetalol or hydralazine should be given.
Proper Monitoring of High Blood Pressure During Pregnancy
When hypertensive disorders are present during pregnancy, the mother and baby must be closely monitored, with frequent prenatal testing to assess the growth and health of the baby. Close monitoring helps catch signs of worsening conditions (if the mother develops complications or the baby has nonreassuring tests). Tests include:
- Non-stress tests (NSTs)
- Bbiophysical profiles (BPPs)
- Amniotic fluid index (AFIs)
- Doppler flow monitoring
In many cases, a planned, early delivery is necessary to prevent the baby from being in sub-optimal conditions for longer than necessary.
Hospitalization is the best way to ensure close monitoring, testing and prompt delivery. This is typically required when a mother has severe hypertension or preeclampsia. Hospitalization also helps the medical team establish the severity and rate of disease progression.
If the mother chooses outpatient monitoring, she must receive check-ups and evaluations as well as fetal testing every 1 – 3 days, and she must have quick access to medical care and a labor and delivery unit. Pregnant women should be aware of the signs and symptoms of significant blood pressure changes and preeclampsia; they should monitor the baby’s movements every day.
Mothers should be told to call their obstetricians immediately if they develop:
- Severe or persistent headache
- Visual changes
- Shortness of breath
- Pain in the upper abdomen.
As with any pregnancy, the mother should go to the hospital right away if there is:
- Decreased movement of the baby
- Vaginal bleeding
- Abdominal pain
- Rupture of the membranes
- Uterine contractions.
Proper Timing of Delivery for High Blood Pressure During Pregnancy
In many cases, delivery of a baby in cases where the mother has preeclampsia occurs early. Time of delivery is based on several factors, including:
- Severity of the high BP / preeclampsia
- How well-controlled the mother’s BP is
- Whether complicating factors are present (e.g., placental abruption)
- Gestational age of the baby.
Preeclampsia at 37 weeks or later requires delivery. If there is any evidence of significant maternal end-organ dysfunction or nonreassuring tests of the baby’s well-being, the baby is delivered, regardless of gestational age. When non-severe preeclampsia is present, expectant management is reasonable, but delivery must occur as soon as the mother develops signs or symptoms of severe preeclampsia/eclampsia (or at 37 weeks if the disease does not progress to the severe stage).
The Takeaway: Proper Monitoring, Treatment and Timing of Delivery is Critical For Good Outcomes in Preeclampsia
When a mother has a hypertensive disorder, failure to carefully manage her blood pressure and properly monitor and assess the health of the baby can cause the baby to have severe birth injuries, such as hypoxic ischemic encephalopathy (HIE), seizures, permanent brain damage and cerebral palsy. It is crucial to give correct medications to the mother and deliver the baby at the appropriate time. For more information on the link between preeclampsia and birth injuries, see our page on preeclampsia mismanagement.
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