Hypertensive disease of pregnancy, also known as maternal hypertensive disorder, is a group of high blood pressure disorders that include preeclampsia, preeclampsia superimposed on chronic hypertension, gestational hypertension, and chronic hypertension.
Maternal hypertensive disorders occurred in about 20.7 million women in 2013. About 10% of pregnancies globally are complicated by hypertensive diseases. In the United States, hypertensive disease of pregnancy affects about 8% to 13% of pregnancies. Rates have increased in the developing world. They resulted in 29,000 deaths in 2013, down from 37,000 deaths in 1990. They are one of the three major causes of death in pregnancy (16%) along with post partum bleeding (13%) and puerperal infections (2%).
Hypertensive disorders during pregnancy, such as gestational hypertension, preeclampsia, and eclampsia, are a major contributor to maternal and fetal illness and death on a worldwide scale. Around 5-10% of pregnancies are affected by these conditions, with preeclampsia being responsible for up to 14% of maternal deaths globally. The effects of HDP are significant, but there is still a limited understanding of its root causes. Studies show an interconnection of genetic, immunological, and environmental elements. Accurately pinpointing particular risk factors has stifled researchers because of the varied nature of Hypertensive disorders of pregnancy. All types of HDP can be caused by a variety of factors, as mentioned above, and can occur in irregular manners.
Signs and symptoms 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 (often called gestational hypertension).
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 pre-eclampsia, placental abruption (when the placenta separates from the wall of the uterus), and gestational diabetes. These women also face a higher risk for poor birth outcomes such as pre-term delivery, having an infant small for his/her gestational age, and infant death.
Risk factors Some women have a greater risk of developing hypertension during pregnancy. These are: Women with chronic hypertension (high blood pressure before becoming pregnant). 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 before pregnancy. Pregnant women under the age of 15 or over the age of 30. Women who are pregnant with more than one baby. Women with diabetes, kidney disease, rheumatoid arthritis, lupus, or scleroderma. Woman who use artificial reproductive technologies
Diagnosis There is no single test to predict or diagnose preeclampsia. Key signs are increased blood pressure and protein in the urine (proteinuria). Other symptoms that seem to occur with preeclampsia include persistent headaches, blurred vision or sensitivity to light, and abdominal pain.
Other disorders can cause all of these sensations; they can also occur in healthy pregnancies. Regular visits are scheduled to track blood pressure and protein levels 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 Pressure Education Program Working Group on High Blood Pressure in Pregnancy: Chronic hypertension; Preeclampsia-eclampsia; Preeclampsia superimposed on chronic hypertension; Gestational hypertension (transient hypertension of pregnancy or chronic hypertension identified in the latter half of pregnancy).
This terminology is preferred over the older but widely used term pregnancy-induced hypertension (PIH) because it is more precise. The newer terminology reflects simply relation of pregnancy with either the onset or first detection of hypertension; 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.
Chronic hypertension Chronic hypertension is a type of high blood pressure in a pregnant woman that is pre-existing before conception, diagnosed early in pregnancy, or persists significantly after the end of pregnancy. It affects about 5% of all pregnancies and can be a primary disorder of essential hypertension or secondary to another condition; it is not caused by pregnancy itself.
The diagnostic criteria for chronic hypertension are typically considered to be at least two separate blood pressure readings taken at least four hours apart with systolic blood pressure ≥ 140mmHg, diastolic blood pressure ≥90 mmHg, or both, identified before pregnancy, before 20 weeks of gestation, or persisting at least 12 weeks after giving birth. However, there is some controversy over the utility of adopting lower thresholds for the diagnosis of chronic hypertension, which is more consistent with recent recommendations from the American College of Cardiology and the American Heart Association for the diagnosis of hypertension in adults. Chronic hypertension in pregnancy is now considered mild if blood pressures do not exceed 159 mmHg systolic and 109 mmHg diastolic and severe if pressures are ≥ 160 mmHg systolic or 110 mmHg diastolic, although controversy also exists as to the most appropriate cutoffs for this definition.
Because chronic hypertension can progress to more severe forms of disease, it is important to accurately diagnose the condition early, ideally before pregnancy, and initiate management to control parental blood pressure. This is often difficult, as many reproductive individuals may not regularly visit the doctor and, when pregnant, may initially present for prenatal care in the second trimester.
Pre-eclampsia and eclampsia Preeclampsia is a medical condition which usually develops after 20 weeks of gestation and traditionally involves both newly increased blood pressure (blood pressure > 140/90 mmHg) and proteinuria. Importantly, preeclampsia can first develop after delivery, even in those who had normal blood pressure throughout their pregnancy.
Preeclampsia is a leading cause of fetal complications, which include low birth weight, preterm birth, and stillbirth. Women with preeclampsia are encouraged to deliver the child after 37 weeks of gestation to minimize the risks of severe complications.
Preeclampsia, the most severe type of HDP, has been a major subject of research for scientists. Preeclampsia is usually characterized by elevated blood pressure and frequently protein in the urine after the 20th week of pregnancy, believed to be caused by abnormal placental growth leading to endothelial dysfunction and inflammation. Nevertheless, the order of these occurrences is still debated, making targeted treatment strategies more challenging. Furthermore, preventive measures are delayed because current criteria only show evidence in the second or third trimesters.
Recent studies have identified important biomarkers linked to HDP, such as placental growth factor. Unusual levels of this angiogenic factor and others have shown potential for forecasting preeclampsia, which could enable earlier intervention and improved monitoring. Furthermore, scientists are studying lifestyle factors such as diet and physical activity to evaluate their potential to reduce HDP risk, although definitive conclusions have not yet been reached.
Preeclampsia can also be diagnosed if a woman has both increased blood pressure and 1 or more signs of significant organ damage. Signs of significant organ damage include: Severely elevated blood pressure (blood pressure > 160/110) Thrombocytopenia Increased or rapidly elevating levels of creatinine in the blood Increased liver enzymes Pulmonary edema New or persistent headaches that do not respond to pain medication Blurred or altered vision
If a woman with preeclampsia has any of these signs of significant organ damage, then her condition is classified as preeclampsia with severe features. This diagnosis can be made even if the patient does not have proteinuria. Women with preeclampsia with severe features are encouraged to deliver the child after 34 weeks of gestation to minimize the risks of severe complications.
Preeclampsia can also present with seizures in the pregnant mother. In this case, the patient would be diagnosed with eclampsia.
There is no proven way to prevent preeclampsia/eclampsia. Most women who develop signs of preeclampsia, however, are closely monitored to lessen or avoid related problems. The only way to "cure" preeclampsia/eclampsia is to deliver or abort the baby.
Eclampsia Eclampsia is one particularly concerning form of preeclampsia in which a pregnant woman who previously presented with signs of newly increased blood pressure begins to experience new generalized seizures or coma. Up to 70% of patients with eclampsia experience complications associated with pregnancy. These complications can include HELLP syndrome, acute kidney injury, and disseminated intravascular coagulation among others.
HELLP Syndrome HELLP syndrome is a type of preeclampsia with severe features that involve increased hemolysis, increased liver enzymes, and low platelet levels. While most women with HELLP syndrome have high blood pressure and proteinuria, up to 20% of HELLP syndrome cases do not present with these classical signs of preeclampsia. However, like pre-eclampsia, HELLP syndrome can also lead to low birth weight and premature birth of the fetus/neonate. HELLP syndrome has a fetal/neonatal mortality rate of 7-20%.
Preeclampsia superimposed on chronic hypertension Preeclampsia superimposed on chronic hypertension occurs when a pregnant woman with chronic hypertension develops signs of pre-eclampsia, typically defined as new onset of proteinuria ≥30 mg/dL (1+ in the dipstick) in at least 2 random urine specimens that were collected ≥4 h apart (but within a 7-day interval) or 0.3 g in a 24-h period. Like ordinary pre-eclampsia, superimposed pre-eclampsia can also occur with severe features, which are defined as: systolic blood pressure ≥160 mmHg or diastolic blood pressure ≥110 mmHg despite escalation of antihypertensive therapy; thrombocytopenia (platelet count <100,000/microL); impaired liver function; new-onset or worsening renal insufficiency; pulmonary edema; or persistent cerebral or visual disturbances. As a result, superimposed pre-eclampsia can be diagnosed without proteinuria when a sudden increase in previously well-controlled blood pressure is accompanied by severe features of pre-eclampsia.
Gestational hypertension Gestational hypertension is a provisional diagnosis that involves newly increased blood pressure in a pregnant woman that usually develops after 20 weeks of gestation but does not currently show any signs of proteinuria or other features associated with preeclampsia. Up to 50% of gestational hypertension patients go on to develop some form of preeclampsia.