Hypertensive Disorders: Prevalence, Perinatal Outcomes and Cesarean Section Rates in Pregnant Women Hospitalized for Delivery

Objective  To evaluate the prevalence of hypertensive disorders, perinatal outcomes (preterm infants, low birthweight infants and Apgar score < 7 at the 5th minute and fetal deaths) and the cesarean rates in pregnant women hospitalized for delivery at the Maternidade Hilda Brandão da Santa Casa de Belo Horizonte, Belo Horizonte, state of Minas Gerais, Brazil, from March 1, 2008 to February 28, 2018. Methods  A case-control study was performed, and the groups selected for comparison were those of pregnant women with and without hypertensive disorders. Out of the 36,724 women, 4,464 were diagnosed with hypertensive disorders and 32,260 did not present hypertensive disorders Results  The prevalence of hypertensive disorders was 12.16%; the perinatal outcomes and cesarean rates between the 2 groups with and without hypertensive disorders were: preterm infants (21.70% versus 9.66%, odds ratio [OR] 2.59, 95% confidence interval [CI], 2.40–2.80, p  < 0.001); low birthweight infants (24.48% versus 10.56%; OR 2.75; 95% CI, 2.55–2.96; p  < 0.001); Apgar score < 7 at the 5 th minute (1.40% versus 1.10%; OR 1.27; 95% CI, 0.97–1.67; p  = 0.84); dead fetuses diagnosed prior to delivery (1.90% versus 0.91%; OR 2.12; 95% CI, 1.67–2.70; p  < 0.001); cesarean rates (60.22% versus 31.21%; OR 3.34; 95% CI, 3.14–3.55; p  < 0.001). Conclusion  Hypertensive disorders are associated with higher rates of cesarean deliveries and higher risk of preterm infants, low birthweight infants and a higher risk of fetal deaths.


Introduction
Hypertensive disorders complicate up to 10% of all pregnancies and are one of the main causes of maternal and perinatal morbidity and mortality, besides playing a key role in prematurity. [1][2][3] Hypertensive disorders are classified into four categories: 1) pre-eclampsia (PE)-eclampsia, 2) chronic hypertension (of any etiology), 3) chronic hypertension with superimposed PE and 4) gestational hypertension. 1,[4][5][6] Pre-eclampsia affects 2 to 8% of pregnant women. 6 The main maternal complications in PE are eclampsia, coagulopathy (disseminated intravascular coagulation), stroke, pulmonary edema, severe renal failure, liver infarction or hemorrhage, myocardial infarction, retinal injury, placental abruption and death. 1,5-8 Eclampsia affects $ 3.2% of patients suffering from PE with severe features. 6,9 It occurs in a ratio of 1/2000 deliveries in developed countries and from 1/100 to 1/1,700 deliveries in developing countries. 9 HELLP syndrome (H: hemolysis; EL: elevated liver enzymes; LP: low platelet) is associated with high rates of maternal morbidity and mortality. 1,6,10,11 Its occurrence is $ 1 to 2% in patients with PE with severe features. 12 In PE, placental ischemia may lead to fetal growth restriction and placental abruption with a subsequent increased risk of prematurity. Other complications are perinatal death and hypoxia-related neurological injuries. 1,6,13,14 Induction of labor can be performed as long as fetal well-being is assured and maternal clinical conditions allow. 15,16 In cases of gestational hypertension and PE without severe features, pregnancy should be followed-up with maternal and fetal assessment, and delivery can be scheduled for the 37 th week of pregnancy. 17,18 Immediate termination of pregnancy, once diagnosed after 36 weeks, is related to a reduction in the risk of PE with severe features, HELLP syndrome, eclampsia, pulmonary edema and placental abruption, when compared with pregnant women with pregnancy management beyond 36 weeks, neither leading to increased neonatal morbidity nor higher c-section rates. 18 Gestational hypertension may progress, in almost half of the cases, to PE. 1,4,6 In cases of gestational hypertension or PE with severe features, delivery is recommended when the diagnosis is done at or beyond the 34 th week. 19 Chronic hypertension (CH) affects up to 5% of pregnant women. 1 Maternal risks related to CH such as maternal mortality, stroke, pulmonary edema or renal failure are 5 to 6 times higher than in normotensive women. 20,21 The risk of gestational diabetes is also increased. 22 Increased prematurity is directly related to the indication for termination of pregnancy, with a 2-fold higher incidence of fetal growth restriction when compared with women not affected by CH. 23 Chronic hypertension with superimposed PE is characterized by the onset of PE in hypertensive patients prior to pregnancy. It affects from 20 to 50% of chronically hypertensive patients. 20,24,25 Cesarean Section Rates The number of cesarean sections has been increasing over the years around the world. Global rates increased from 12.1% in 2000 to 21.1% in 2015. 26 In Brazil, in 2010, c-section rates reached as high as 52.33% of all deliveries and 55.43%, in 2016. 27 The mode of delivery in patients with hypertensive disorders will depend on maternal and fetal clinical conditions as well as on gestational age. 6

Low Birthweight Infant
Newborns < 2,500 g are already considered low weight. 28 About 20 million low birthweight and premature newborns are born annually around the world, and one third die before reaching the age of 1 year. 30 In Brazil, perinatal conditions such as birth asphyxia, infections and respiratory problems are the main causes of infant mortality and are more frequent in preterm and low birthweight infants. 30

APGAR Score
The APGAR score was described by Dr. Virginia Apgar in 1953 and is a tool for classifying the clinical condition of newborns soon after birth and assessing the effectiveness of resuscitation measures whenever necessary. 31 The persistence of a low APGAR score at the 5 th minute indicates the need for further therapeutic efforts and the severity of the underlying problem of the baby. If the 5-minute APGAR score is > 6, perinatal asphyxia is rather unlikely to happen. 32

Outcomes Measures
The primary outcome was the prevalence of hypertensive disorders and the secondary outcomes were c-section rates and perinatal outcomes (APGAR score < 7 at 5 minutes, low birthweight (LBW) infants, preterm infants and stillbirths) in pregnant women admitted to the hospital with and without hypertensive disorders for delivery care.

Statistical Analysis
The statistical methodology used was the two proportions Ztest for comparisons, with a 5% significance level. Therefore, p-values < 0.05 were considered statistically significant. Throughout the study period, there were 2,531 cases of PE (2,171 women classified as PE-eclampsia and 360 women classified as CH with superimposed PE), with a prevalence of 6.89%, and 876 cases of gestational hypertension, with a prevalence of 2.39%. There were 36 cases of eclampsia, 1 case for every 1,020.1 deliveries, or 1 case for every 70.3 women with PE, with an incidence of 1.42%. There were 115 cases of HELLP syndrome, 105 cases in patients classified as PE/eclampsia and 10 cases in patients classified as CH with superimposing PE, with an incidence of 4.54%. There were 1,417 cases of CH (1,057 women classified as CH and 360 classified as CH with superimposed PE), with a prevalence of 3.86%. Of the 1,417 pregnant women with CH, 360 had superimposed PE, affecting 25.41% of women with CH. Cesarean section rates in pregnant women with hypertensive disorders were 60.22%, and in the control group 31.21%; OR 3.34; 95% CI, 3.14-3.55; p < 0.001 (►Table 1).
The dead fetuses diagnosed prior to delivery were excluded from the APGAR analysis (385 in the general population, or 1.03%), with 87 (1.90%) out of the total number of newborns in pregnant women with hypertension and 298 Fig. 1 Year on year prevalence of hypertensive disorders at the Maternidade Hilda Brandão.

Conclusion
Hypertensive disorders are associated with a higher proportion of c-section deliveries, preterm newborns and LBW infants. The proportion of dead fetuses before hospital admission for delivery is also higher in pregnant women with hypertensive disorders. Therefore, good prenatal care is essential to prevent fetal death before hospital admission for delivery. The evaluation of newborns by the APGAR score at 5 minutes showed no significant differences between the proportion of newborns with APGAR < 7 at 5 minutes for pregnant women with and without hypertensive disorders, which leads to the understanding that adequate and timely delivery assistance is critical to good fetal conditions at birth.

Contributions
Data collection and article writing was performed by the maternity coordinator physician Ramos Filho F. L. Professor Antunes C. M. F. did the analysis and interpretation of data.

Conflict of Interests
The authors have no conflict of interests to declare.  Abbreviations: CI, confidence interval; OR, odds ratio.