European Journal of Obstetrics & Gynecology and Reproductive Biology
Perinatal outcomes, blood pressure patterns and risk assessment of superimposed preeclampsia in mild chronic hypertensive pregnancy
Introduction
Chronic hypertension in pregnancy is associated with serious maternal and foetal complications, including premature birth, foetal growth restriction (FGR), foetal demise, placental abruption and caesarean delivery [1]. These complications have a substantial economic impact, including costs of monitoring and treating sick mothers and neonates.
According to the National High Blood Pressure Program Working Group on High Blood Pressure in Pregnancy, chronic hypertension is defined as hypertension present before the 20th week of pregnancy or hypertension present before pregnancy [2]. Chronic hypertension in pregnancy can be classified as mild or severe; cut-offs commonly used to define “severe” are blood pressure (BP) of 160/110 mmHg or higher in the American literature and 170/110 mmHg or higher in the European literature [3].
The incidence of chronic hypertension in pregnancy ranges from 0.5 to 5%, depending on the populations studied and the diagnostic criteria used. At the University of Tennessee, Memphis, where the referral area is large and 80% of the obstetric patients are indigent Blacks, the incidence is 3.4% [2], [4].
It is often difficult to diagnose chronic hypertension in pregnant women who do not have documented prepregnancy blood pressure recordings. In these cases, the presence of elevated blood pressure before 20 weeks’ gestation establishes the diagnosis and hypertension should be documented on more than one occasion and at Korotkoff phase V [2]. Nevertheless, the ambulatory blood pressure monitoring for 24 h (ABPM 24-h) is considered to be a useful clinical method for defining more precisely BP elevation by the elaboration of several parameters such as mean, mesor and circadian rhythm.
Several physiologic changes occur in pregnancy that may modify the natural history of chronic hypertension, such as the increase in blood volume or the increased renal function, but the most important occurrence in pregnancy is the trophoblastic invasion of the spiral arteries at 16–18 weeks, which leads to a physiologic blood pressure decrease in normal pregnancy. This phenomenon of maternal “adaptation” to pregnancy may influence the natural course of both hypertension and pregnancy. Chesley and Annitto [5] observed that chronic hypertensives demonstrate greater decreases in blood pressure during pregnancy than normotensives, and that blood pressure was within the normal range in the second trimester in women who were severely hypertensive before pregnancy. In addition, Sibai et al. [6] found that blood pressure was within the normal range during the second trimester in 49% of 211 women who had mild chronic hypertension during pregnancy. The majority of these women subsequently developed increased blood pressure during the third trimester, and thus may be erroneously diagnosed as having pregnancy-induced hypertension. This change can mask either the course or the detection of chronic hypertension in early pregnancy [1]. On the other hand, superimposed preeclampsia in pregnancy complicated by chronic hypertension may be associated with worsening or malignant hypertension, central nervous system haemorrhage, cardiac decompensation and renal failure. The reported incidence of superimposed preeclampsia in patients with chronic hypertension ranges from 4.7 to 52% [5], [7], [8].
On the basis of evaluation before conception, women with chronic hypertension can be divided into “high-risk” or “low-risk” by the presence or absence of organ involvement. The management of low-risk chronic hypertension is still controversial and the role of antihypertensive therapy in pregnancy outcomes is particularly uncertain.
The primary outcome of this study was to determine the perinatal outcomes in a population of pregnant women with low-risk chronic hypertension; the secondary aim was to investigate the parameters useful in identifying chronic hypertension pregnancies at risk of superimposed preeclampsia and adverse perinatal outcomes.
Section snippets
Materials and methods
We investigated two groups of singleton pregnancies: 223 patients with mild chronic hypertension (study group) consecutively seen at the Department of Obstetrics and Gynecology of Marche Polytechnic University, Ancona (Italy), over a four-year period (1999–2003), and all normotensive women with normal singleton pregnancies were enrolled consecutively in the same period, and matched for maternal age and parity. In this group, 200 women were selected who were and remained normotensive and had a
Results
In Table 1, the demographics and characteristics of all subjects included in the study are displayed. The two groups were comparable for age, gravidity and smoking habits. In the study group, the body weight and the rate of previous preeclampsia were significantly higher and among hypertensive women the prevalence of essential hypertension (95% versus 5%) was higher too. In the chronically hypertensive group, we identified a subgroup of chronically hypertensive women with (34.9%; n = 78) and
Discussion
In general, most mild chronic hypertensives (low-risk group) will have a pregnancy outcome similar to that of the general obstetric population. They have a good perinatal outcome regardless of the use of antihypertensive medication, while superimposed preeclampsia is an indication for hospitalisation and close evaluation of maternal and foetal well-being. The course of blood pressure in the second trimester may be used as a prognostic indicator for future exacerbation of hypertension. Although
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Cited by (20)
Physiologic blood pressure patterns in pregnancies with mild chronic hypertension
2024, Pregnancy HypertensionChronic hypertension and superimposed preeclampsia: screening and diagnosis
2022, American Journal of Obstetrics and GynecologyCitation Excerpt :In addition, 2 further studies reported a 2- and 4-fold increase in the risk of superimposed PE in women with chronic hypertension and a mean arterial BP of ≥95 mm Hg in the first trimester of pregnancy13 and a diastolic BP of ≥100 mm Hg in the second trimester of pregnancy, respectively.14 Although models incorporating BP parameters along with maternal characteristics perform modestly in the prediction of superimposed PE,13,16 the performance is equivalent, if not better, to those incorporating biomarkers discussed later in the review (Table 3). It has been argued that women with chronic hypertension and uncontrolled BP should be managed in the same way as those with superimposed PE.17
Pregnancy complications in chronic hypertensive patients are linked to pre-pregnancy maternal cardiac function and structure
2020, American Journal of Obstetrics and GynecologyPreeclampsia and Hypertensive Disorders
2016, Obstetrics: Normal and Problem PregnanciesChronic hypertension and pregnancy
2014, Chesley's Hypertensive Disorders in Pregnancy, Fourth EditionEpidural-associated hypotension is more common among severely preeclamptic patients in labor
2012, American Journal of Obstetrics and GynecologyCitation Excerpt :Women with severe preeclampsia superimposed on chronic hypertension were included in our cohort as these patients comprise a significant proportion of severe preeclamptic patients in our population. As chronic hypertensive women with superimposed severe preeclampsia may be at increased risk for adverse perinatal outcomes than those with isolated preeclampsia, we thought it important that these patients be represented in our cohort.16 To meet criteria for preeclampsia based on proteinuria, women with chronic hypertension had to demonstrate an acute increase in 24-hour urine protein excretion by over 300 mg in a 24-hour urine collection after a baseline value less than 150 mg in 24 hours before 20 weeks' gestation.