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Effect of Maternal Congenital Heart Defects on Labor and Delivery Outcome: A Population-Based Study

April 24, 2007

By Sidlik, Rakefet; Sheiner, Eyal; Levy, Amalia; Wiznitzer, Arnon

Abstract

Objective. The primary objective of this study was to characterize the delivery outcome of parturients with congenital heart defects (CHD), from maternal and from neonatal perspectives.

Study design. A retrospective population-based study was conducted, covering a 13-year period (1989-2002) with an aggregate of 151487 deliveries of all women with and without CHD. Maternal demographics, obstetrical and medical history, delivery outcome, and neonatal outcome were drawn from a computerized perinatal database.

Results. Sixty-seven women with CHD had 156 deliveries. The severity of CHD, based on the New York Heart Association (NYHA) classification, was I or II in 99.1% of the deliveries. CHD patients had significantly higher rates of labor induction and neonatal malformations. Maternal CHD was discovered as an independent risk factor associated with neonatal malformations (OR 2.10, 95% CI 1.18- 3.72). No significant differences were noted between women with CHD and the controls regarding maternal morbidities and Apgar scores.

Conclusions. The labor outcome of CHD patients with NYHA classification I and II resembles that of non-CHD women in a tertiary center setting. Neonates of CHD mothers have higher rates of congenital malformations even among asymptomatic or mildly symptomatic mothers. A careful sonographic follow-up is warranted among all pregnancies of CHD patients.

Keywords: Congenital heart disease, high risk pregnancy, maternal heart disease, neonatal outcome, neonatal malformations

Introduction

Thanks to developments in surgical techniques and the advancements in medical care that have occurred over the last 30 years, pregnancies in women with congenital heart diseases occur more frequently now than in the past [1]. This is due to the fact that prior to these advancements, these women rarely survived to become fecund. The relatively high prevalence of heart disease at reproductive age complicates up to 1% of pregnancies. The most common congenital lesions suffered by this population are: ventricular septal defect (VSD), atrial septal defect (ASD), and aortic stenosis (AS), mostly due to a bicuspid aortic valve [1].

During pregnancy, maternal cardiac function is influenced by gestational hormones and as a result cardiac output increases concomitantly to the decrease in arterial blood pressure [2]. In addition, the fetal ferrum consumption may cause maternal anemia that results in a further increase in the maternal heart rate [3]. VSD, ASD, and patent ductus arteriosus (PDA) are related to a left- to-right shunt and to pulmonary hypertension, which is considered a serious risk factor [4-6].

Several articles have addressed the direct effect of maternal CHD on pregnancy, labor, and delivery outcome. According to these articles, high rates of spontaneous abortions and maternal and fetal morbidity and death are found among these women. Furthermore, these women have been found to have a higher rate of cesarean deliveries [7-9]. Also, Siu et al. [10] found that the proportion of premature deliveries and of infants with low birth weight is higher among women with heart diseases. In the presence of a cardiac lesion, the physiological changes may have a dramatic effect on the course of labor and delivery. Severe symptoms in these patients enable prediction of complicated labor and risk of deterioration in functional status during delivery [4,5]. This study aimed to evaluate the differences between the course of labor and delivery outcome of women with CHD and women without CHD.

The incidence of congenital heart malformations in fetuses is about 8 in 1000 births [U]. According to Oberhansli et al. [12] the recurrence rate of congenital heart defects in fetuses increases, in general by a factor of five, if the mother suffers from a CHD. The recurrence rate depends on the type of cardiac defect. Previous studies have shown a recurrence rate of 3.5-8.8% for an offspring when one of the parents is affected [13-16]. A higher incidence of CHD in the fetus occurs when there is a maternal CHD than if there is a paternal CHD [14-16]. In most cases the cause is multifactorial, and involves both inherited and environmental factors. Epidemiological studies have shown an association between CHD and maternal diabetes, flu or fever, smoking, and use of marijuana or exposure to other chemical substances [17-20]. Still, there are no studies showing a direct association between the types of maternal and fetal CHDs. Our second objective was to examine this possible association, and to evaluate the fetal outcome of women with CHD.

Methods

This retrospective population-based study included 156 deliveries of 67 CHD patients out of 151487 deliveries conducted at the Soroka University Medical Center between January 1989 and December 2002. Data were obtained for all deliveries from the perinatal computerized database of the Department of Obstetrics and Gynecology. This information was recorded directly onto the database after delivery by the obstetrician treating the patient. Soroka University Medical Center is the sole hospital in the Negev, the southern part of Israel, and consequently treats the entire obstetrical population. Treatment of patients with CHD is given in the medical center by a multidisciplinary team composed of obstetricians, cardiologists, anesthesiologists, and pediatricians. This study was approved by the joint local committee of Soroka University Medical Center and Ben-Gurion University of the Negev on August 2004.

The classification of maternal congenital heart malformation was accomplished according to the ICD9-CM (International Classification of Diseases, 9th revision, Clinical Modification) codes for ‘congenital heart disease’ (64851 is the general code for maternal congenital heart malformation, and specific malformation classification was accomplished according to codes 745-1 to 747-9). Demographics, clinical characteristics, and obstetric risk factors were studied, including maternal age, ethnicity, gravidity, parity, age of pregnancy, and neonatal gender. Obstetric risk factors included: fertility treatments, chronic hypertension, gestational diabetes (type A dietary care, type B – insulin treatment), diabetes mellitus, fever during pregnancy, and smoking and alcohol consumption.

The following characteristics were investigated as representative of pregnancy, labor, and delivery outcome: prior cesarean deliveries, history of abortions, prior perinatal deaths, pulmonary hypertension, oligohydramnios (amniotic fluid index (AFI) 24 cm), intrauterine growth restriction (IUGR), premature rupture of membranes (PROM), induction of labor (by Foley catheter, prostaglandin E2, oxytocin, or early amniotomy), oxytocin augmentation, acceleration of labor, mal-presentation, non- reassuring fetal heart rate patterns, meconium-stained amniotic fluid, mode of delivery (partum spontaneous, instrumental, or cesarean), post-partum hemorrhage (blood loss > 500 mL in vaginal delivery or > 1000 mL in cesarean section), hemoglobin level, blood transfusion, and length of hospitalization.

The following neonatal outcomes were assessed: presence of congenital heart malformations in the infant and its classification, presence of other malformations in the neonate, and perinatal death. The above outcomes were determined in a primary physical examination by a pediatrician. Information regarding previous children with CHD was obtained from the maternal records.

The 67 patients and 156 deliveries of mothers matching the ICD-9- CM criteria were further reviewed using the hospital archive. The basic clinical maternal characteristics included: the type of CHD, need for medical or surgical treatment due to CHD, and classification of severity according to the New York Heart Association (NYHA) that was deduced from information documented in the medical records [4]. In addition, information regarding the present pregnancy characteristics was collected, including: shortness of breath symptoms, palpitations, general weakness during pregnancy, pulmonary edema, and central cyanosis.

Maternal cardiac complications during and after labor were assessed by: blood pressure changes, tachycardia, arrhythmia, dyspnea, and pulmonary edema as well as the need for furosemide treatment.

Monitor tracings were re-interpreted by the authors with the use of the National Institute of Child Health and Human Development Research Planning Workshop guidelines [9].

The information regarding two separate deliveries by one of the patients was not further analysed due to accessibility difficulties.

Statistical analysis was performed using the SPSS12 package (SPSS, Chicago, IL, USA). Statistical significance was ascertained using the Chi-square test for differences in categorical variables and the t-test for differences in continuous variables. A multivariable logistic regression model was constructed in order to define independent risk factors associated with maternal CHD while controlling for confounders. Odds ratios (OR) and 95% confidence intervals (CI) were computed and p

Results

The population study included 67 cases of women with CHD who had 156 deliveries, and a control group which included 151331 deliveries.

Demographic and cl\inical characteristics of the two groups are shown in Table I. No significant differences were found regarding these characteristics, as well as parity and neonatal gender between the groups. A significant difference was noted regarding the ethnicity, with a relatively higher rate of Jewish patients in the CHD group. The severity of heart disease, evaluated for 154 patients according to the NYHA classification, was I in 115 pregnancies (74.6%), II in 38 pregnancies (24.7%), and III in one pregnancy (0.6%).

The types of CHD in the study women are presented in Table II, the most prevalent being VSD, bicuspid aortic valve, aortic valve regurgitation, ASD, and mitral valve regurgitation. Table III compares obstetric risk factors between the study group and the control group. Higher rates of labor induction, insulin-treated gestational diabetes mellitus, and fertility treatment were noted in the CHD group compared to the control group. No other obstetric risk factor was found to be significant.

A multivariable logistic regression was constructed in order to define the factors associated with maternal CHD (Table IV). The identified independent factors were fertility treatments and ethnicity (Jewish).

Table I. Demographic and clinical characteristics.

Table V compares the labor and neonatal outcome in the study groups. In 21 of the 154 labors (13.6%), patients suffered from maternal cardiac complications (furosemide treatment was given to six of the women in labor, blood pressure increase occurred in four cases and decrease in three cases, dyspnea was noted in three cases, and arrhythmia occurred in three).

Significantly higher rates of congenital malformations, 27 out of 154 (17.5%), were found in neonates of CHD mothers. Thus we conducted another multivariable logistic regression model with congenital malformations as the outcome variable (Table VI). Maternal CHD was found as an independent risk factor for neonatal malformations (OR 2.1, 95% CI 1.18-3.72).

In the CHD group, there were 10 neonates who suffered from cardiac malformations and 17 who suffered from non-cardiac malformations. Several neonates suffered from multiple malformations that were coded separately; these are presented in Table VII.

No correlation was found between maternal and neonatal malformations. Two pregnancies in the maternal CHD group (1.3%) ended in perinatal death. In one case the neonate suffered from Jeune syndrome with multiple malformations including atrioventricular canal. In the second case the neonate suffered from oligohydramnios sequence including right ventricle hypoplasia.

Discussion

This study shows no significant difference between delivery outcome of women with CHD of NYHA classification I or II and women without CHD. This result may be explained by the NYHA good functional status of the study group, as previous studies have shown that cardiovascular maternal morbidity and mortality during pregnancy correlate with the maternal functional status [5,21]. The multidisciplinary treatment in a tertiary center such as the Soroka University Medical Center may also have contributed to this result; several studies have shown that treatment given by a multidisciplinary team, including obstetricians, cardiologists, anesthesiologists, and pediatricians, is an important factor in achieving a low maternal mortality and morbidity rate, as well as the attainment of a healthy course of pregnancy and delivery [1,9,22- 24].

Table II. Types of congenital heart diseases among women in the study.

Table III. Obstetric risk factors of pregnancies among women with and without congenital heart disease.

Table IV. Factors associated with maternal congenital heart disease. Results from a multivariable analysis with backward stepwise elimination.*

The higher rates of fertility treatment and labor induction noted in the CHD group points to a more intensive medical involvement in this group.

It is noted that no higher rates of cesarean section were found in the CHD group, and this finding contradicts previous studies [7- 9]. The combination of higher rates of labor induction with similar rates of cesarean section may be explained by the tendency to treat women with CHD more aggressively, even when cardiac function is preserved and symptoms are not present. At the same time, before performing a cesarean section, doctors follow denned indications, the approach is more conservative, and since most of the patients in this study suffered from mild heart diseases there was no significant difference in cesarean section rate between the groups. The sample size of pregnant women with CHD and the mild severity of heart diseases in this study limit the conclusions that can be drawn from this result. A future investigation with a larger sample is recommended.

A significantly higher rate of Jewish patients with CHD was noted in our study. This may be explained by a lack of diagnosis of CHD in the Bedouin society. The Bedouin society is very traditional and conservative, thus Bedouin women tend to underutilize medical services in general, and prenatal care particularly [25,26]. This may also lead to lower numbers of Bedouin women with CHD reaching dieir years of fertility.

Significantly higher rates of neonatal malformations were found in the maternal CHD group, though most of the women in our study were classified with a mild heart disease and did not suffer major symptoms during pregnancy and labor. These results correlate with previous studies [12-16,27]. Ten neonates in the case group had congenital heart disease (6.5%), a rate that is similar to the recurrence rate of CHD presented in previous studies [13-15]. It is reasonable to assume that the actual rate of neonatal CHD is somewhat higher since mild lesions, without any symptoms or findings, may be under-diagnosed shortly after delivery [28], and this study covered only the short-term diagnosis. Concordance rates in previous studies between maternal and neonatal CHD vary widely and depend on the CHD type [28,29]. No correlation was found between the type of maternal CHD and neonatal CHD, although the sample size may be too small to determine such correlations. Nevertheless, our study emphasizes that maternal CHD is an independent risk factor for neonatal malformations (OR 2.1). These data warrant the use of a careful sonographic follow-up during pregnancy, even in the presence of a mild maternal heart disease.

Table V. Labor and perinatal outcomes of pregnancies among women with and without congenital heart disease.

Table VI. Multiple logistic regressions with backward elimination for factors associated with neonatal outcome of malformations.

Table VII. Neonatal malformations among neonates of congenital heart disease mothers.

In conclusion, women with minor CHD or with asymptomatic CHD can bear delivery without cardiac difficulties and have a good prognosis. The labor outcome of women with CHD of NYHA classification I and II resembles that of non-CHD women in a tertiary center setting.

Neonates of CHD mothers have higher rates of congenital malformations even among asymptomatic or mildly symptomatic mothers. A careful sonographic follow-up is warranted among all pregnancies of CHD patients.

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RAKEFET SIDLIK1, EYAL SHEINER1, AMALIA LEVY2, & ARNON WIZNITZER1

1 Department of Obstetrics & Gynecology, Faculty of Health Services, Soroka University Medical Center, Ben-Gurion

University of the Negev, Beer-Sheva, Israel and 2 Epidemiology and Health Services Evaluation Department, Faculty of Health

Services, Soroka University Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel

(Received 26 April 2006; revised 10 July 2006; accepted 10 July 2006)

Correspondence: Eyal Sheiner MD, Department of Obstetrics & Gynecology, Faculty of Health Services, Soroka University Medical Center, Ben-Gurion University of the Negev, Beer-Sheva, Israel 84841. E-mail: sheiner@jbgu.ac.il

Copyright Taylor & Francis Ltd. Mar 2007

(c) 2007 Journal of Maternal – Fetal & Neonatal Medicine. Provided by ProQuest Information and Learning. All rights Reserved.




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