Chronic hypertension: first-trimester blood pressure control and likelihood of severe hypertension, preeclampsia, and small for gestational age

摘要

Background There is extensive evidence that pre-pregnancy chronic hypertension is associated with high risk of development of severe hypertension and preeclampsia and birth of small for gestational age neonates. However, previous studies have not reported whether anti-hypertensive use, blood pressure control or normalization of blood pressure during early pregnancy influence the rates of these pregnancy complications. Objective To stratify women with pre-pregnancy chronic hypertension according to the use of antihypertensive medications and level of blood pressure control at the first hospital visit during the first-trimester of pregnancy and examine the rates of severe hypertension, preeclampsia and birth of small for gestational age neonates according to such stratification. Study Design Prospective study of 586 women with pre-pregnancy chronic hypertension, in the absence of renal or liver disease, booked at a dedicated clinic for the management of hypertension in pregnancy. The patients had singleton pregnancies and were subdivided according to findings in their first visit into group 1 (n=199), with blood pressure 140/90 mmHg without antihypertensive medication, group 2 (n=220), with blood pressure 140/90 mmHg with antihypertensive medication and group 3 (n=167), with systolic blood pressure 140 mmHg and or diastolic blood pressure 90 mmHg despite antihypertensive medication. In the subsequent management of these pregnancies our policy was to maintain the blood pressure at 130-140 / 80-90 mmHg with use of antihypertensive medication; antihypertensive drugs were stopped if the blood pressure was persistently less than 130/80 mmHg. The outcome measures were severe hypertension (systolic blood pressure 160 mmHg and / or diastolic blood pressure 110 mmHg), preterm and term preeclampsia (in addition to hypertension at least one of renal involvement, liver impairment, neurological complications or thrombocytopenia), and birth of small for gestational age neonates (birth weight 5th percentile for gestational age). The incidence of these complications was compared in the three strata. Results The median gestational age at presentation was 10.0 (interquartile range 9.1-11.0) weeks. In groups 2 and 3, compared to group 1, there was a significantly higher body mass index, incidence of black racial origin and history of preeclampsia in a previous pregnancy. There was a significant increase from group 1 to group 3 in incidence of severe hypertension (10.6%, 22.2% and 52.1%), preterm preeclampsia with onset at 37 weeks of gestation (7.0%, 15.9% and 20.4%), and small for gestational age (13.1%, 17.7% and 21.1%), but not term preeclampsia with onset at 37 weeks of gestation (9.5%, 9.1% and 6.6%). Conclusions In women with pre-pregnancy chronic hypertension, the rates of development of severe hypertension, preterm preeclampsia and small for gestational age are related to use of antihypertensive medications and level of blood pressure control at the first hospital visit during the first-trimester of pregnancy.