What causes pregnancy-induced hypertension?

The cause of pregnancy-induced hypertension (PIH) is not known. It appears in 5 percent of pregnant women. It is more likely to occur during first pregnancies, in women less than 25 years old, and in women more than 35 years old. Pregnant women who have chronic hypertension, kidney disease or diabetes  or who are pregnant with more than one baby have a greater chance of developing PIH.

Dr. Jeanne Morrison, PhD
Family Practitioner
The cause of pregnancy induced hypertension (PIH) is unknown. What is known is that the increase in blood pressure is directly related to the presence of the pregnancy, the incidence of PIH is greater in multiple gestation pregnancies and PIH resolves when the pregnancy ends.
Diana Meeks
Diana Meeks on behalf of Sigma Nursing
Family Practitioner

Researchers do not know the primary cause of pregnancy-induced hypertension (PIH). This condition occurs when a pregnant woman's blood pressure rises for some unknown reason. The rise in blood pressure causes protein in your urine and edema, which is swelling from water retention. This happens often in women who are either younger than 20 or older than 40 or are carrying more than one baby.

Women who had high blood pressure before pregnancy or suffer from kidney problems or diabetes also increase their risk for PIH.

Weight can also affect pregnancy-induced hypertension (PIH) in a variety of ways. First, those who are overweight or obese are more likely to suffer from PIH during their pregnancies. PIH also manifests itself by a sudden influx in weight. This is why many doctors caution you not to overly indulge on junk food before or during pregnancy.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.