by Stephen Janowsky

Created on: June 11, 2008

Increased blood pressure (BP), a.k.a. hypertension, is found in ten percent of all pregnant women. There may be two kinds of hypertension during pregnancy: chronic hypertension (which is not directly linked to pregnancy, often precedes it, and typically persists after delivery) and pregnancy-induced hypertension (PIH or preeclampsia).

Preeclampsia usually occurs in the third trimester of pregnancy and, besides increased BP, it also presents with edema (ankle swelling) and proteinuria (abnormal urinary loss of protein). The cause of this disorder is unknown, but its mechanism seems to be a deficient blood supply to the placenta (called placental ischaemia). However, it is the most common cause of disease and death during pregnancy, for both mother and fetus. In the mother, preeclampsia may complicate with severe (possibly life-threatening) conditions, like: seizures (eclampsia), acute renal failure, widespread blood clotting within blood vessels (intravascular coagulation), and liver impairment with low platelet count (the HELLP syndrome). All of these complications require immediate hospitalization in intensive care, and urgent termination of pregnancy; after delivery, all troubles usually resolve within less than two weeks. With preeclampsia, there is also an increased risk of miscarriage, stillbirth, and fetal growth restriction.

The diagnosis of pregnancy hypertension is made when the diastolic BP is found to be above 90 mm Hg on two separate occasions. Hypertension is more readily chronic if there is a history of high BP before pregnancy, if it is found earlier than 20 weeks of gestation, if there is no proteinuria, or if the BP remains high after childbirth. In such cases, the cause of this hypertension must be searched for, considering such disorders as chronic kidney disease, adrenal adenoma, and kidney artery obstruction. On the other hand, preeclampsia is more probable if the onset of hypertension is beyond the 20th week of pregnancy and/or if there is also proteinuria. When the diagnosis of preeclampsia is established, there are no further investigations to do, except to closely follow the patient's evolution, in order to detect any signs of possible complications. In this case, the BP is expected to return to normal soon after delivery.

Medical surveillance of a pregnant woman with PIH involves physical and laboratory examination every 2-4 weeks during the first and second trimesters, and every 1-2 weeks during the third trimester of gestation. These

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