Predicting hypertension in pregnancy

A recent study has indicated that several weeks before pregnant women show signs of a dangerously high blood pressure, they have impaired blood flow in their arteries and elevated blood levels of a hypertension-promoting substance. The researchers said that the results of this study may help the development of more accurate tests for the prediction and more effective treatment of pre-eclampsia. Pre-eclampsia is a poorly understood pregnancy-induced condition marked by high blood pressure and elevated levels of protein in the urine. It affects pregnant women in their third trimester of pregnancy and poses a risk to both the mother and the fetus. In severe cases, pre-eclampsia can lead to maternal seizures and even death. The condition resolves when the baby is born. Researchers from the King's College Hospital in London studied 86 pregnant women who underwent ultrasound testing during their second trimester to see if they had normal uterine blood flow.

It was found that half the women had a normal uterine flow, while the others did not, suggesting they were at risk for pre-eclampsia or other complications. The results showed that none of the 43 women who had normal uterine blood flow developed pre-eclampsia during their third trimesters. Among the 43 women with abnormal uterine blood flow, 10 went on to develop pre-eclampsia, 14 delivered underweight babies due to growth restriction in the womb and 19 had normal pregnancies. Second-trimester testing also showed that half of the women with abnormal uterine blood flow had elevated blood levels of asymmetric dimethylarginine, or ADMA, which impairs the ability of blood vessels to widen. This happens because ADMA inhibits the effects of nitric oxide, which helps keep blood vessels relaxed and blood pressure in check. Additional ultrasound testing in the second trimester showed that, compared with women who did not develop pre-eclampsia, those who did had more restricted blood flow in their arms. This suggested that the presence of blood vessel dysfunction that occurred before pre-eclampsia had been diagnosed. And the more restricted the blood flow, the higher the blood levels of ADMA, the researchers reported. The findings suggest that doctors might be able to better predict pre-eclampsia by checking blood flow in the arms in addition to the uterus. And since an amino acid known as L-arginine can help counter the effects of ADMA, it may be worth exploring whether L-arginine can help stave off pre-eclampsia in high-risk women, they conclude.

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