Although many pregnant women with high blood pressure have healthy babies without serious problems, high blood pressure can be dangerous for both the mother and baby. Women with pre-existing, or chronic, high blood pressure are more likely to have certain complications during pregnancy than those with normal blood pressure. However, some women develop high blood pressure while they are pregnant. Chronic poorly-controlled high blood pressure before and during pregnancy puts a pregnant woman and her baby at risk for problems. It is associated with an increased risk for maternal complications such as preeclampsia, placental abruption, and gestational diabetes. These women also face a higher risk for poor birth outcomes such as preterm delivery, having an infant small for his/her gestational age, and infant death.
Risks
Some women have a greater risk of developing hypertension during pregnancy. These are:
Women with chronic hypertension.
Women who developed high blood pressure or preeclampsia during a previous pregnancy, especially if these conditions occurred early in the pregnancy.
Women who are obese prior to pregnancy.
Pregnant women under the age of 20 or over the age of 40.
Women who are pregnant with more than one baby.
Women with diabetes, kidney disease, rheumatoid arthritis, lupus, or scleroderma.
Diagnosis
There is no single test to predict or diagnose preeclampsia. Key signs are increased blood pressure and protein in the urine. Other symptoms that seem to occur with preeclampsia include persistent headaches, blurred vision or sensitivity to light, and abdominal pain. All of these sensations can be caused by other disorders; they can also occur in healthy pregnancies. Regular visits are scheduled to track blood pressure and level of protein in urine, to order and analyze blood tests that detect signs of preeclampsia, and to monitor fetal development more closely.
Classification
A classification of hypertensive disorders of pregnancy uses 4 categories as recommended by the U.S. National High Blood PressureEducation Program Working Group on High Blood Pressure in Pregnancy:
Chronic hypertension;
Preeclampsia-eclampsia;
Preeclampsia superimposed on chronic hypertension;
Gestational hypertension.
This terminology is preferred over the older but widely used term pregnancy-induced hypertension because it is more precise. The newer terminology reflects simply relation of pregnancy with either the onset or first detection of hypertension and that the question of causation, while pathogenetically interesting, is not the important point for most health care purposes. This classification treats HELLP syndrome as a type of preeclampsia rather than a parallel entity.
Preeclampsia
is a condition that typically starts after the 20th week of pregnancy and is related to increased blood pressure and protein in the mother's urine. Preeclampsia affects the placenta, and it can affect the mother's kidney, liver, and brain. When preeclampsia causes seizures, the condition is known as eclampsia--the second leading cause of maternal death in the U.S. Preeclampsia is also a leading cause of fetal complications, which include low birth weight, premature birth, and stillbirth. There is no proven way to prevent preeclampsia. Most women who develop signs of preeclampsia, however, are closely monitored to lessen or avoid related problems. The only way to "cure" preeclampsia is to deliver or abort the baby.
Prevention
Blood pressure control can be accomplished before pregnancy. Medications can control blood pressure. Certain medications may not be ideal for blood pressure control during pregnancy such as angiotensin-converting enzyme inhibitors and angiotensin II receptor antagonists. Controlling weight gain during pregnancy can help reduce the risk of hypertension during pregnancy. There is limited evidence to suggest that calcium supplementation may reduce the risk of pre-eclampsia or stillbirth but it is unclear if it has other benefits.
Prognosis
The effects of high blood pressure during pregnancy vary depending on the disorder and other factors. Preeclampsia does not in general increase a woman's risk for developing chronic hypertension or other heart-related problems. Women with normal blood pressure who develop preeclampsia after the 20th week of their first pregnancy, short-term complications, including increased blood pressure, usually go away within about six weeks after delivery. Some women, however, may be more likely to develop high blood pressure or other heart disease later in life. More research is needed to determine the long-term health effects of hypertensive disorders in pregnancy and to develop better methods for identifying, diagnosing, and treating women at risk for these conditions. Even though high blood pressure and related disorders during pregnancy can be serious, most women with high blood pressure and those who develop preeclampsia have successful pregnancies. Obtaining early and regular prenatal care for pregnant women is important to identity and treat blood pressure disorders.
Epidemiology
High blood pressure problems occur in six percent to eight percent of all pregnancies in the U.S., about 70 percent of which are first-time pregnancies. In 1998, more than 146,320 cases of preeclampsia alone were diagnosed. Although the proportion of pregnancies with gestational hypertension and eclampsia has remained about the same in the U.S. over the past decade, the rate of preeclampsia has increased by nearly one-third. This increase is due in part to a rise in the numbers of older mothers and of multiple births, where preeclampsia occurs more frequently. For example, in 1998 birth rates among women ages 30 to 44 and the number of births to women ages 45 and older were at the highest levels in three decades, according to the National Center for Health Statistics. Furthermore, between 1980 and 1998, rates of twin births increased about 50 percent overall and 1,000 percent among women ages 45 to 49; rates of triplet and other higher-order multiple births jumped more than 400 percent overall, and 1,000 percent among women in their 40s.
