General antepartum obstetrical ultrasound has become a standard part of gestational care and is commonly used for the determination of fetal age, size, gender, or wellbeing, and for the detection of congenital anomalies (Bhat et al, 2004; Davey et al, 2009). To date, almost every structural congenital heart disease (CHD) described in postnatal life has been detected in utero by fetal cardiac ultrasound (Garne et al, 2001). Although most major anomalies of the heart can be identified at 18–22 weeks of gestation by fetal echocardiography, these defects are usually missing during routine antenatal scanning (Finch et al, 2006; El Guindi et al, 2013). Therefore, paying attention to high-risk and influencing factors on CHD can be very helpful in timely diagnosis.
A variety of maternal or fetal disorders may result in abnormality of the fetal cardiovascular system to a degree which demands evaluation at a level above and beyond that attainable with standard antepartum obstetrical ultrasound. In these circumstances, a fetal echocardiography should be performed (Bhat et al, 2004; Davey et al, 2009).
Fetal echocardiography has been accepted as a prenatal non-invasive method, diagnostic tool and ultrasonic evaluation of cardiovascular diseases in fetuses for more than three decades (Becker et al, 2001; Nabulsi et al, 2003). However, there are some fetal and maternal factors that increase the risk of CHD. During these studies, some of maternal and fetal factors such as infections, maternal smoking, and gestational diabetes mellitus, stillbirth etc were associated with congenital fetal heart disease (Venugopalan et al, 2003; Tamar et al, 2005; Ul Haq et al, 2011). Therefore, in our opinion, reviewing the records of pregnant women referred to fetal echocardiography which can provide useful clinical information. As prenatal diagnosis provides the opportunities for counseling of the family, anticipatory care and potential surgical intervention discussions. Therefore, we decided to conduct a study on pregnant women referred for fetal echocardiography in the city of Ahvaz, Iran from 2017–2020 and compare some of the obstetrical, fetal, and maternal records of patients who had normal and abnormal echocardiography. The aim of this study was to find out which adverse pregnancy outcomes occur in people with abnormal echocardiography compared to people with normal echocardiography.
Methods
This study was a retrospective study that was obtained by reading the information in the records of women referred for fetal echocardiography. After reviewing, we compared the records of women who had normal and abnormal echocardiography. The aim of this study was to determine the predictors factor of abnormal fetal echocardiography. The study population consists of all pregnant women referred for fetal heart echo in the years 2017–2020 in Ahvaz, Iran. The records of all pregnant women (1 772 persons) referred for fetal echocardiography for any reason were examined and reviewed. In this study, all tests and screenings were performed on patients and only the data in the records of patients was reviewed.
The data were collected by one of the researchers (SA) in a checklist pre-prepared by the research team. Fetal echocardiography was performed on the subjects and data such as maternal age, gestational age, history of previous child's heart disease, body mass index (BMI), gravidity, number of deliveries, number of abortions, type of mother's disease, history of poor obstetrical outcomes such as history of stillbirth, gestational diabetes mellitus (GDM), gestational hypertension, preeclampsia etc and fetal factors such as increased nuchal translucency (NT) and fetal aneuploidy screening data were collected and were compared in two groups with normal and abnormal echocardiography.
In addition, all the required data were in the patients' files and no data was missing. Pearson correlation coefficient and Spearman correlation coefficient were used to analyse the data. SPSS statistical programme version 22 was used for data analysis. Continuous data was expressed as mean±standard deviation (SD). Comparison of variables was assessed by using Chisquare or Fisher's extracts tests and the significance level was less than 5%. This study was approved by the Ethics Committee of Ahvaz Jundishapur University of Medical Sciences (IRAJUMS.REC.1399.392).
Results
Comparison of variables was done on 1 772 referred pregnant women for fetal echocardiography, 1 739 had normal fetal echocardiography (98.1%) and 33 had abnormal fetal echocardiography (0.9%). The mean±SD of pregnant women's age, gestational age and BMI were 31.7±3.1 years, 21.4±4.3 weeks, and 26.0±7.7 kg/m2 respectively. The most common causes of referral for fetal cardiac evaluation were abnormality in ultrasounds (57.6%).
In total, 40.2% were multipara and 59.8% were nullipara. The relative risk of abnormal fetal echocardiography in pregnant women who were multiparous was 0.56 times higher than in pregnant women who were nulliparous but there was not a significant statical relationship (P>0.05) (Table 1).
Table 1. Obstetric characteristics of participants by normal and abnormal fetal echocardiography
| Obstetric characteristics | Normal echocardiography | Abnormal echocardiography | P | Obstetric characteristics | Normal echocardi ography | Abnormal echocardi ography | P | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Num | % | Num | % | Num | % | Num | % | ||||||
| BMI | Under weight | 73 | 4.2 | 3 | 9.1 | 0.27 | Number of fetus | 1 | 1 639 | 94.2 | 31 | 93.9 | 0.94 |
| Normal | 653 | 37.6 | 15 | 45.5 | 2 | 94 | 5.4 | 2 | 6.1 | ||||
| Overweight | 655 | 37.7 | 8 | 24.2 | 3 | 5 | 0.3 | 0 | 0 | ||||
| Obese | 355 | 20.4 | 7 | 21.2 | >3 | 1 | 0.1 | 0 | 0 | ||||
| Parity | Nullipara | 1 045 | 60.1 | 16 | 48.5 | 0.12 | ART | Non | 1 584 | 91.1 | 32 | 96.8 | 0.22 |
| Multipara | 694 | 39.9 | 17 | 51.5 | IVF | 129 | 7.4 | 1 | 3.2 | ||||
| History of still-birth | 0 | 1 624 | 93.4 | 29 | 87.8 | 0.000 | IUI | 26 | 1.5 | 0 | 0 | ||
| 1 | 98 | 5.6 | 3 | 9.0 | Number of deliveries | 0 | 718 | 41.3 | 16 | 48.5 | 0.27 | ||
| 2 | 14 | 0.7 | 0 | 0 | 1 | 656 | 37.7 | 12 | 36.1 | ||||
| 3 | 2 | 0.1 | 0 | 0 | 2 | 281 | 16.2 | 3 | 9.0 | ||||
| >3 | 1 | 0.1 | 1 | 3.2 | 3 | 75 | 4.3 | 1 | 3.2 | ||||
| Maternal DM | Yes | 21 | 1.2 | 0 | 0 | 0.94 | >3 | 9 | 0.5 | 1 | 3.2 | ||
| No | 1 718 | 98.8 | 33 | 100 | Maternal GDM | Yes | 172 | 9.9 | 6 | 18.2 | 0.11 | ||
| Chronic hyper tension | Yes | 2 | 0.1 | 0 | 0 | 0.78 | No | 1 567 | 90.1 | 27 | 81.8 | ||
| No | 1 737 | 99.9 | 33 | 100 | Gestational hypertension | Yes | 7 | 0.4 | 0 | 0 | 0.93 | ||
| No | 1 732 | 99.6 | 33 | 100 | |||||||||
| History of abortion | Yes | 466 | 26.3 | 12 | 36.4 | 0.03 | |||||||
| No | 1 273 | 73.7 | 21 | 63.6 | |||||||||
BMI: body mass index, DM: diabetes mellitus, ART: assisted reproductive technology, GDM: gestational diabetes mellitus, IVF: in vitro fertilisation, IUI: intrauterine insemination
A total of 1.5% of women had more than three abortions and 27% of them had at least one abortion. There was a significant relationship between the number of abortions and abnormal fetal echocardiography (P<0.05). The relative risk of abnormal echo in pregnant women who had a history of miscarriage was 56.1 times higher than pregnant women who had no history of miscarriage and this relationship was statistically significant (P<0.05) (Table 1).
Among the subjects, 12.6% had abnormal NT and only 4.3% of women had high-risk screening test. A total of 12% of pregnant women with abnormal fetal echocardiography had history of CHD in prior offspring. Also, the high-risk screening test reported in only 3% of them. There was no statistically significant relationship between above items with abnormal fetal echocardiography (P>0.05) (Table 2). But there was a significant relationship with having Down's syndrome in prior offspring (P<0.05) (Table 2).
Table 2. Fetal factors and family history of participants by normal and abnormal fetal echocardiography
| Characteristics | Normal echocardiography | Abnormal echocardiography | P | ||||
|---|---|---|---|---|---|---|---|
| Num | % | Num | % | ||||
| Fetal factors | Increased NT | Normal | 1 521 | 87.5 | 27 | 81.8 | 0.23 |
| Abnormal | 218 | 12.5 | 6 | 18.2 | |||
| Fetal aneuploidy screening | Low risk | 1 573 | 90.4 | 32 | 96.7 | 0.53 | |
| Moderate risk | 105 | 6.1 | 0 | 0 | |||
| High risk | 61 | 3.5 | 1 | 3.3 | |||
| Family history | CHD in prior offspring | Yes | 1 630 | 93.7 | 4 | 12.12 | 0.17 |
| No | 109 | 6.3 | 29 | 87.8 | |||
| Down syndrome in prior offspring | Yes | 30 | 0.1 | 3 | 9.1 | ||
| No | 1 709 | 99.9 | 30 | 90.9 | 0.04 | ||
NT: Nuchal translucency; CHD: Congenital heart disease
Most pregnant women in this study did not use any specific medication. The most common used drugs were insulin and metformin, 4.8% and 1.6% respectively (Table 3). Of the subjects, 10% had GDM. None of the pregnant women who had the abnormal echocardiogram have not had diabetes before. There was no significant relationship between diabetes and abnormal echocardiography (Table 1).
Table 3. Type of drug exposure in pregnant women under study
| Type of drug exposure | Normal echocardiography | Abnormal echocardiography | P | ||
|---|---|---|---|---|---|
| Num | % | Num | % | ||
| None | 1 624 | 93.4 | 29 | 87.8 | 0.97 |
| Metformin | 28 | 1.6 | 1 | 3.1 | |
| Insulin | 82 | 4.7 | 3 | 9.1 | |
| Corton | 1 | 0.1 | 0 | 0 | |
| Antiepileptic drugs | 3 | 0.2 | 0 | 0 | |
| Total | 1 739 | 100 | 33 | 100 | |
Discussion
Most fetal cardiac malformations occur in the low-risk pregnancies. Abnormal view of the fetal heart on routine second-trimester screening is highly predictive of congenital heart disease (Ul Haq et al, 2011). Fetal echocardiography has evolved in recent years and has a high rate of diagnostic accuracy. It has been shown to be an accurate screening tool and is widely used in evaluation of cardiac structure and function. Our study also showed that most people with abnormal fetal echocardiography had no history of CHD in their previous child (87.7%). Our findings showed that most women who had an abnormal fetal echocardiography had a normal NT (81.8%) and had low-risk aneuploidy screening test (96.7%). Therefore, attention should not be focused only on high-risk pregnancies.
Comparison of pregnant women with normal and abnormal echocardiography, we found that women with a history of stillbirth, miscarriage, and having a previous child with Down's syndrome are at risk for abnormal echocardiography in their next pregnancy. This risk was also higher in multiparous women.
In this study, there was no statistically significant relationship between abnormal fetal echocardiography and gestational diabetes as well as maternal diabetes, while in the study by Roman Starikov et al (2013), it was reported that poor glycemic control in early pregnancy is associated with an increased risk of CHD in offspring. The incidence of CHD in patients with adequate glycemic control still is sufficiently high to justify routine fetal echocardiography for all gravidas with preexisting diabetes regardless of HbA1c level (Starikov et al, 2013). However, the results of some studies showed that screening diabetic mothers for fetal cardiac malformations could be beneficial (Odibo et al, 2006; Sekhavat et al, 2010; Tabib et al, 2013).
In this study, there was a statistically significant relationship between abnormal fetal echocardiography and having a previous child with Down's syndrome. Also, the previous study indicates that fetal echocardiography probably is very important to families who have previously had a child with a serious malformation (Gudrun et al, 1997). In this present study, the most common referral indication for fetal echocardiography in pregnant women referred to the echocardiography department was suspected CHD on ultrasound. Another study that conducted by Vahedian et al (2019) in Iran confirms this finding.
Most pregnant mothers diagnosed with major CHD had a history of abortion. Various previous studies have confirmed our findings (Simpson et al, 2004; Clur et al, 2008; Nair et al, 2016). In study by Clur et al (2008), they reported that variety of CHD is associated with an increased NT (Simpson et al, 2004) but in our study, such a relationship was not found.
Conclusion
The results of this study can be very important and practical in the field of gynaecology and obstetrics. Important findings of this study include the need for great care in pregnant women who do not have a previous history of having a child with heart disease because according to the results of our study, most cases of abnormal echocardiography were in a group without history of CHD in prior offspring, as well as the association between abnormal echocardiography with adverse pregnancy outcomes such as a history of miscarriage and stillbirth, as well as history of having a child with Down's syndrome. The results of this study can be the basis for further studies. Therefore, it is suggested that other studies with a larger sample size be performed in other communities as well as the outcome of pregnancy.
Study limitations
The data in this retrospective study was related to pregnant women who have been suspected of fetal cardiac defects and referred for echocardiography by each attending obstetrician and pediatric cardiologist. The study samples did not include all pregnant women. This article is part of a research project that aims to investigate the most common reason for referring pregnant women for echocardiography. In the present study, we have compared information about people with normal and abnormal echocardiography, and reviewed their records. Therefore, it is suggested that another study be performed, considering this aim as the primary outcome with larger sample size.