Pregnant women with disorders that cause high blood pressure should have labour induced once pregnancy reaches the 37-week mark, according to a study released Tuesday.
The new recommendations apply in particular to patients with mild pre-eclampsia, a condition that causes hypertension, swelling and sudden weight gain in expectant mothers.
The only way to relieve the symptoms -- which in extreme cases can lead to death -- is to give birth.
About seven percent of all pregnancies are complicated by hypertension disorders, including pre-eclampsia, which can contribute to health problems during pregnancy.
But it has remained unclear whether it was better for the well-being of the woman to systematically induce delivery in case of consistent high blood pressure, or to allow such pregnancies to continue until labour occurs spontaneously.
To find out, a team of researchers in the Netherlands led by Corine Koopmans of University Medical Centre in Groningen set up a clinical trial with 756 women past the 36th week of their pregnancy -- all with mild hypertension or pre-eclampsia -- divided into two, randomly selected groups.
One underwent induced labour, while the other was monitored during the final phase of pregnancy, reported the study, published in the British medical journal The Lancet.
Nearly 30 percent fewer women in the first group experienced any of the severe problems that researchers identified as constituting a "poor maternal outcome," such as full-fledged eclampsia, severe blood pressure or fluid accumulation in the lungs.
No cases of maternal or newborn deaths occurred in either group.
"Induction of labour at 37 weeks' gestation and beyond seems to improve obstetric outcomes in patients with hypertension and pre-eclampsia," Donna Johnson, a researcher at the Medical University of South Carolina, said in a commentary, also in The Lancet.
"This approach should be incorporated into clinical practice."