Hypertension, defined as blood pressure of over 140/90, occurs in 5 to 10 percent of pregnancies. There's a difference between chronic hypertension and pregnancy-induced hypertension (PIH), which develops after the 20 week of pregnancy and can lead to pre-eclampsia, eclampsia or hemolytic anemia elevated liver enzymes and low platelet count (HELLP) syndrome. New theories, such as those reported in the December 2008 issue of "Vascular Health and Risk Management," suggest that abnormal implantation of the placenta or damage to the placenta from minute blood clots may cause PIH.
Signs of PIH
Pregnancy-induced hypertension, also called gestational hypertension, is diagnosed when a woman's blood pressure rises after the 20th week of gestation. One sign of PIH is a blood pressure reading 140/90 or higher when measured in a sitting position; pregnant women who are lying down can have falsely high readings from compression of blood vessels by the uterus, according to Paul Gibson, M.D., in the article "Hypertension and Pregnancy."
Another sign of PIH is the presence of protein in the urine as measured by urinalysis. While a trace or 1+ protein is not uncommon in pregnancy, 2+ protein or higher is abnormal. Edema, or swelling, may occur in the face and hands, although swelling is no longer considered diagnostic of PIH, according to Dr. Gibson.
Symptoms of Progressive PIH
Pre-eclampsia develops in about a third of women with gestational hypertension. Rapid weight gain may occur, due to fluid retention as well as the leakage of fluid from capillary blood vessels, according to Dr. Gibson. Other symptoms of PIH or pre-eclampsia include a new-onset severe frontal headache, abdominal pain caused by the swelling of the liver and reflexes that are more brisk than normal for pregnancy, when women usually have brisker-than-normal reflexes. Vision may be disturbed due to cerebral vasospasm, retinal detachment or retinal vasospasm. Light sensitivity may also be present.
If pre-eclampsia progresses to eclampsia, seizures occur. Eclampsia is the second highest cause of maternal death in pregnancy and can cause cerebral hemorrhage, kidney failure, liver damage and disseminated intravascular coagulation, a disorder that destroys the blood clotting factors.
Around 10 percent of women with pre-eclampsia develop HELLP syndrome, which can develop before or after delivery. Symptoms are similar to those of pre-eclampsia but more severe. Fetal complications include lack of blood flow to the uterus, placental abruption, intrauterine growth retardation, death in utero or premature delivery.
According to the National Heart and Lung Institute, having PIH does not mean that a women will have hypertension after delivery, although it may take six weeks for blood pressure to return to normal.