Rates of adverse perinatal outcomes were no different between women who achieved tight control of mild to moderate hypertension during pregnancy and those who achieved less tight control in an international randomized trial.
The findings, published Jan. 29 in the New England Journal of Medicine, showed no significant differences in a composite of pregnancy loss (including miscarriage, ectopic pregnancy, pregnancy termination, stillbirth, or neonatal death) or high-level neonatal care exceeding 48 hours between women with tight control (30.7%) and less tight control (31.4%). There were also no significant differences in serious maternal complications between the two levels of hypertension control.
The results come from the Control of Hypertension in Pregnancy Study ( CHIPS ), a randomized trial that assessed perinatal outcomes in 986 hypertensive pregnant women treated at 94 sites during a 3-year period.
The appropriate blood pressure targets for women with nonsevere hypertension during pregnancy have been hotly debated, with some research indicating that tight control yields maternal benefits and other studies suggesting it causes problems for the fetus, including poor fetal growth. However, most of the relevant randomized, controlled trials have been small or of moderate or poor quality, according to the CHIPS researchers.
Meanwhile, international guidelines for nonsevere hypertension during pregnancy vary, recommending either less tight control or tight control.
With CHIPS, the researchers are hoping to settle some of the controversy by directly comparing perinatal and maternal outcomes for tight versus less tight control of nonproteinuric, nonsevere hypertension in pregnancy.
“Our trial is substantially larger than previous trials that have examined the effects of lower versus higher blood pressure targets during pregnancy,” Dr. Laura A. Magee of the British Columbia Women’s Hospital and Health Centre in Vancouver and her colleagues wrote ( N. Engl. J. Med. 2015;372:407-17 ).
The study participants, who had nonproteinuric hypertension that was either preexisting or developed during gestation, were randomly assigned to a tight diastolic blood pressure target of 85 mm Hg (489 women) or a less tight target of 100 mm Hg (497 women). Adherence to antihypertensive therapy was similar between the two groups at approximately 74%, and blood pressure was higher throughout pregnancy in the group with less tight control, according to the study.
CHIPS also showed no significant between-group differences in other perinatal outcomes, such as the frequency of newborns who were small for gestational age and respiratory complications and treatment. Further, there were no significant differences in the secondary outcome of serious maternal complications, and no maternal deaths in either group. However, the rate of severe hypertension was higher among women with less tight blood pressure control (40.6% versus 27.5%), though there was no corresponding increase in stroke or transient ischemic attack.