Burden of Fetal Anomalies among Antenatal Mothers Attending a Public Referral Hospital: A Mixed Cohort Study

Authors: Nidhi Fotedar, Nugehally Raju Ramesh Masthi

Abstract

Background and Objective:

Fetal anomalies or birth defects are structural or functional abnormalities that occur before birth, often leading to significant health issues. The burden of fetal anomalies among antenatal mothers attending a public referral hospital in urban Bangalore is a critical public health concern, reflecting broader issues of maternal and child health in India. Factors such as consanguinity, genetic disorders, and delayed access to healthcare contribute to the high prevalence of anomalies in the country. This study aimed to determine the magnitude and types of fetal anomalies detected through routine ultrasound in an urban referral hospital in Bangalore and to explore associations with maternal demographic and socioeconomic factors.

Methods:

This ambispective study analyzed data from 1432 antenatal mothers who underwent ultrasound screening from July 2021 to June 2022. It included a retrospective review of medical records and a prospective follow-up for pregnancies with detected anomalies. Data on maternal age, consanguinity, parity, and other maternal risk factors were collected using logistic regression to explore associations with congenital anomalies.

Results:

Fetal anomalies were detected in 2.9% of pregnancies (n = 42), with renal system anomalies being the most prevalent (59.5%). Consanguinity was present in 9.9% of cases and showed a significant association with congenital anomalies (odds ratio [OR] = 2.14, p = 0.05). Preterm birth was significantly associated with anomalies (OR = 4.47, p = 0.001). Most anomalies were detected after 30 weeks of gestation, limiting the scope for early intervention.

Conclusions and Global Health Implications:

The study highlights congenital anomalies, particularly renal anomalies, that are prevalent in a public hospital in urban Bangalore. It emphasizes the importance of early antenatal care, targeted-screening, and genetic counseling for at-risk population due to consanguinity. Timely detection and intervention could improve maternal and neonatal outcomes.

INTRODUCTION

Background of the Study

Fetal development is crucial in prenatal care, and ultrasound imaging is vital for detecting anomalies that affect the health of both the unborn child and the mother. Congenital anomalies, often termed birth defects, are structural or functional abnormalities that develop during pregnancy and can be identified before birth, at birth or in infancy.^[1]^ These anomalies significantly contribute to stillbirth and neonatal mortality, causing approximately 240,000 deaths within the first 28 days of life annually.^[2]^ Approximately 6% of babies worldwide are born with a congenital disorder, with true numbers possibly higher due to uncounted terminated pregnancies and stillbirths.^[2]^ Major congenital anomalies, which greatly affect life expectancy, occur in 2–3% of live births and 20–30% of stillbirths. These anomalies account for about 3% of live births and 15–30% of pediatric hospitalizations in the United States.^[2]^ In Sub-Saharan Africa, the prevalence rates range significantly, with some areas reporting more than 7%.^[2]^

Community-based studies indicate a prevalence of congenital anomalies at approximately 261.05/10,000 live births from a sample of 10,193 births.^[3]^ In contrast, hospital-based studies reported a prevalence of 184.48/10,000 births from 802,658 births, with a specific prevalence of 203.33/10,000 live births from 44,392 cases. The most frequently reported anomalies in hospital studies were central nervous system defects and musculoskeletal system anomalies, which exhibited the highest prevalence among live births.^[3]^

In India, congenital anomalies represent a substantial public health concern. With an estimated birth prevalence of 2%, they affected over 500,000 births in 2013 alone, surpassing many high-income countries.^[4]^ This highlights their serious impact on neonatal and childhood health in the country.^[5]^

Prenatal ultrasounds are essential in modern obstetrics, providing crucial insights into fetal development and maternal health.^[6]^ Most women have two standard ultrasounds during One at 12–14 weeks for early abnormality detection and gestational dating, and another at 20–22 weeks for a detailed fetal growth assessment. Early first-trimester ultrasounds are increasingly used to detect severe fetal anomalies.^[7]^ Studies show that while some issues may not appear until later, the ability to identify major anomalies increases with gestational age, rising from 10-15% in the late first trimester to over 50% by 20 weeks, and up to 80% in the third trimester.^[8,9]^

In India, a considerable number of congenital anomalies are diagnosed late in pregnancy or after birth. A study at a tertiary care center found that 7.6% of pregnancies had fetal structural malformations, with many identified after 20 weeks.^[10]^ This delay restricts options for families and may lead to unsafe termination practices. Congenital anomalies are caused by various factors, including genetic issues, environmental influences, and maternal health. Major causes include consanguineous marriages, high birth rate, maternal infections, and nutritional deficiencies.^[1,5,11]^ Timely maternal vaccination and improved prenatal care could prevent a significant number of these anomalies, as highlighted by the World Health Organization.^[12]^

India is applying public health strategies to address congenital anomalies through prevention, early detection, and management. Initiatives like fortifying staple foods with folic acid aim to decrease neural tube defects, and improved prenatal screening helps identify anomalies early for prompt intervention.^[3]^ However, challenges such as the need for better surveillance systems, standardized screening protocols, and increased public awareness still exist.^[4,11]^

This study aims to examine fetal anomalies in a public hospital serving a diverse population with varying access to antenatal care. We seek to identify patterns and risk factors associated with congenital anomalies to inform targeted interventions and improve prenatal care protocols. The hospital offers free ultrasound assessments and services to pregnant mothers, particularly those from economically disadvantaged backgrounds.

Study Objectives

Given this context, we need to address the study with (1) to describe the demographic characteristics of antenatal mothers with fetal anomalies, and (2) to explore the epidemiological features linked to these mother fetuses.

METHODS

Study Setting and Participants

This research was conducted at a public referral hospital in Bengaluru, where, on average, more than 700 deliveries are conducted annually. Women from the catchment primary and secondary healthcare facilities are referred to this hospital, particularly for specialized maternal care, including ultrasound assessments. The study included a retrospective review of medical records and a prospective follow-up for pregnancies with detected anomalies. The study incorporated 1,432 antenatal mothers who underwent ultrasound evaluations at the hospital between July 2021 and June 2022.

Inclusion and Exclusion Criteria

The study included antenatal mothers who attended the hospital for ultrasound assessments during the specified period, with gestational ages ranging from 11 to 42 weeks. Records considered incomplete or solely for dating scans were excluded. The selection process is illustrated in Figure 1.

Data Collection

Data was retrospectively collected from hospital medical records, including demographics (age, parity, gestational age, socioeconomic status as determined by the Modified BG Prasad Socioeconomic Scale [2022]), consanguinity, ultrasound results, and identified congenital anomalies. Pregnant women with an anomalous fetus were contacted by phone to follow up on their pregnancy outcomes and delivery method.

Ultrasound Screening

Ultrasound examinations were conducted by a radiologist specialized in fetal medicine, with at least 5 years of experience operating Philips 350 ultrasound systems (Serial szn1680192). The examinations were performed through the abdominal approach, adhering to the guidelines established by the International Society of Ultrasound in Obstetrics and Gynecology for the first, second, and third-trimester scans. When necessary, complementary transvaginal examinations were carried out using a volumetric endocavitary transducer. In accordance with departmental protocol, second-trimester (18–24 weeks) and third-trimester (32–36 weeks) ultrasound examinations were offered to all pregnant women following an initial first-trimester scan (11–13 weeks).

Classification and Categorization of Congenital Anomalies

Identified anomalies during the ultrasound were categorized based on the impacted organ systems. Categories included renal, cardiac, central nervous system, gastrointestinal, musculoskeletal, among others. Further distinctions were based on specific diagnoses. After the ultrasound, mothers with anomalous fetuses were contacted by phone to determine pregnancy outcomes.

Statistical Analysis

The data was extracted from ultrasound reports and mother–child protection cards and then transferred to Google Spreadsheets (Google LLC., State of Delaware, USA). The data were analyzed using the R software in R Studio (Version 2023.12.1+402), with additional tools from the R Commander statistical packages.

The following variables were Maternal age, parity, history of consanguinity, number of pregnancies, number of miscarriages, and associated maternal factors such as anemia, chronic diseases, diseases acquired during gestation, history of structural abnormalities in previous pregnancies and/or familial history, mode of delivery, and the type and location of the identified structural defects.

Descriptive statistics, such as frequencies and percentages, were used to summarize the demographic details and congenital anomaly burden among the study participants. This included evaluating the prevalence of congenital anomalies and exploring potential maternal and fetal risk factors. Outliers, particularly those due to data entry errors, were identified and excluded after assessing their biological plausibility and clinical relevance. Removing these data points did not significantly affect the study’s conclusions.

To assess the relationship between congenital anomalies and various maternal factors, logistic regression was used. The primary outcome variable was the presence or absence of a congenital anomaly. Predictor variables included maternal age, consanguinity, anemia, preterm status, parity, and socioeconomic status (SES). The logistic regression model was employed to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for each risk factor, adjusting for potential confounders.

Kaplan–Meier survival analysis was conducted to estimate the probability of detecting congenital anomalies over the course of gestation. The gestational age (in weeks) was used as the time variable, and the event of interest was the detection of congenital anomalies through routine ultrasound screening. Kaplan–Meier curves illustrated the time-to-event data, and subgroup analyses were conducted based on factors like SES and consanguinity.

To assess differences in the timing of anomaly detection between subgroups, such as consanguineous and nonconsanguineous pregnancies, the log-rank test was performed. This test compared the survival distributions (i.e., the likelihood of anomaly-free pregnancies) between these groups, allowing for an assessment of whether the timing of anomaly detection varied significantly between them.

RESULTS

Burden

A study of 1,432 antenatal mothers at an urban referral hospital in Bangalore found congenital anomalies in 42 pregnancies, which equates to an overall rate of 2.9% or 29 per 1,000 pregnancies, detected during routine ultrasound examinations.

Demographic and Maternal Factors

In the study cohort, mothers aged 26–30 years constituted the majority at 44.34%, followed by those aged 22–25 years at 39.46%. Mothers aged 18-21 years accounted for 8.52%, while a negligible 0.6% were above the age of 35 years. The majority of cohorts with anomalous fetuses belonging to the age group of 22–25 years accounted for 50% as depicted in Table 1. Regarding the maternal risk factors, anemia was prevalent in 44.5% of the mothers. Other conditions such as oligohydramnios (6.7%), polyhydramnios (4.8%), breech presentation (3.2%), and Rh-negative status (2.9%) were also observed [Table 1].

When assessing the relationship between maternal age and congenital anomalies, no statistically significant association was discerned across the age ranges. Regarding consanguinity, 9.9% of the mothers were in consanguineous marriages. Notably, this group exhibited a statistically significant association with congenital anomalies, evidenced by an OR = 2.14, 95% CI: 0.9–4.7, p = 0.05 [Table 2]. Among the maternal risk factors, only preterm conditions showed a significant association with congenital anomalies (OR = 4.47, 95% CI: 1.7–11.2, p = 0.001) [Table 2].

Types of congenital anomalies

Renal system anomalies were the most prevalent, with a magnitude of 59.5%. Intracardiac echogenic foci were observed in 4.7% of the cases, as noted in Table 3. Other systems, including musculoskeletal (4.7%), cardiovascular (7.1%), central nervous system (2.3%), and gastrointestinal (2.3%), were less frequently represented. Anomalies outside these primary categories made up 23.8% of the identified cases.

Anomalies were predominantly identified at term, accounting for 96.7% of the cases. Two-thirds (66.3%) of anomaly detections occurred after the 30-week mark, with a notable rise in detection rates in the later stages of pregnancy.

On applying logistic regression, p-values approaching significance were only observed in preterm births, and consanguinity remains close to significance.

A log-rank test was conducted to compare the survival distributions of pregnancies with consanguinity and those without consanguinity in relation to the detection of congenital anomalies [Table 4].

The log-rank test indicated no statistically significant difference between the survival curves of consanguineous and non-consanguineous pregnancies in terms of congenital anomaly detection (χ^2^ = 2.3, p = 0.1 ). Although the consanguineous group appeared to have fewer anomalies detected than expected, the difference was not significant at the 5% level (p > 0.05). However, the p-value of 0.1 suggests a potential trend that might warrant further investigation with a larger sample size or more detailed analysis.

The graph below represents the Kaplan–Meier survival analysis of congenital anomalies detected during pregnancy.

Figure 2a shows the X-axis representing gestational age in weeks, and the Y-axis indicates the probability of no anomalies detected (survival probability). The slight decline toward the later stages of pregnancy suggests that anomalies are more likely to be detected closer to term.

In Figure 2b, the X-axis represents gestational age in weeks, while the Y-axis indicates the survival probability. While both groups exhibit similar survival patterns for most of the gestation, the non-consanguineous group shows a slightly lower survival probability toward the later stages, indicating a marginally higher likelihood of anomaly detection near term.

In Figure 2c, the X-axis represents gestational age in weeks, while the Y-axis indicates the survival probability. The curves for different SES classes remain similar until the later stages of gestation, with Class II (Upper middle class) showing a slightly lower survival probability toward the end of the term, suggesting a higher likelihood of anomalies being detected later in pregnancy for this group.

DISCUSSION

This study examines congenital anomalies found through antenatal ultrasound screenings at an urban referral hospital in Bangalore. Our findings highlight the importance of routine ultrasound for early detection and reveal the complex factors that contribute to fetal anomalies.

The overall magnitude of congenital anomalies observed in our study closely aligns with findings from Shah et al., who reported a prevalence of 2.3% in India.^[13]^ This consistency not only validates our findings but also points out the significant burden of congenital anomalies in the country. Furthermore, our findings align with global trends, as reflected in the EUROCAT surveillance network, which reported similar rates of congenital anomalies across Europe. Additionally, a recent study by Verberne et al., identified a prevalence of 2.4% in the Dutch Caribbean islands of Aruba, Bonaire, and Curaçao.^[14]^ The global burden of congenital anomalies is substantial, and the WHO continues to emphasize the need for improved prenatal care.^[15]^

The high number of affected pregnancies highlights the importance of early detection through routine ultrasound screenings. This can improve pregnancy management, prepare for postnatal care, and enable fetal interventions when necessary. It also stresses the need for more resources and specialized care for high-risk cases within India’s healthcare system. These findings underline the urgent requirement for effective congenital anomaly surveillance systems in India.

Renal system anomalies were the most common in our cohort, making up over half of all detected anomalies. This aligns with existing literature that identifies congenital anomalies of the kidney and urinary tract (CAKUT) as one of the most prevalent fetal anomalies detected during routine antenatal ultrasound screening.^[14]^ Additionally, Stein et al. noted that urinary tract dilation is the most frequent anomaly within the CAKUT spectrum, a trend also observed in our cohort.^[16,17]^

The high rate of renal anomalies in our study may be attributed to the timing of ultrasound screenings and the characteristics of these anomalies, which are often easier to detect than other fetal defects. First-trimester ultrasounds can miss some issues, while renal anomalies like hydronephrosis or multicystic dysplastic kidney become more noticeable later in pregnancy, especially in the second or third trimester. This highlights the importance of ongoing monitoring and focused evaluation of the renal system during routine antenatal ultrasounds, particularly for high-risk pregnancies.

Our study identified congenital anomalies across all maternal age groups, with no significant link between maternal age and the occurrence of these anomalies. This aligns with Glinianaia et al.’s 32-year population study, which found minimal impact of advanced maternal age.^[18]^ However, since most mothers in our study were between 22 and 30 years old, this age range may have influenced the results. Future research should focus on a broader age range to better understand age-related risks.

Among maternal risk factors, anemia was the most prevalent, affecting nearly half the mothers [Table 1]. While logistic regression did not find anemia to be significantly associated with congenital anomalies, the high prevalence of anemia highlights the importance of antenatal care and nutritional interventions in mitigating maternal health risks. Anemia was prevalent across the cohort, yet its role in contributing to congenital anomalies remains inconclusive. The WHO has emphasized addressing nutritional deficiencies, particularly iron deficiency anemia, as part of comprehensive antenatal care strategies.^[19]^

Interestingly, preterm status showed a statistically significant association with congenital anomalies. This aligns with global data identifying preterm birth complications as a significant risk factor for neonatal morbidity and mortality.^[20]^

Our findings reveal a significant association between consanguinity and congenital anomalies, suggesting that consanguinity may increase the risk of these disorders. However, this association is not as strong as reported in some previous research. Possible reasons for this difference could include our sample size, the genetic background of our population or other confounding factors. Previous studies, like those by Fareed, Afzal, and Hamamy, have highlighted the greater risk of genetic disorders in consanguineous marriages.^[21,22]^

Regarding SES, no statistically significant association was found between socioeconomic class and congenital anomalies in our study. The predominance of upper-class participants (60.92%) in our sample could have contributed to this outcome by limiting variability in socioeconomic representation. However, studies such as those by Dadvand et al. and Boyle et al. highlight how socioeconomic differences can influence access to healthcare, nutritional status, and maternal education, which indirectly affect maternal and fetal health.^[23,24]^ Thus, the relationship between SES and congenital anomalies is complex and requires further investigation in more diverse populations.

Our study found that most anomalies were detected after 30 weeks of gestation. This late detection highlights the importance of early prenatal care and raises questions about the effectiveness of first and second-trimester ultrasound screenings. Late detections can limit intervention options and increase parental anxiety, underscoring the need for improved early prenatal screening practices.

This finding highlights systemic issues, such as delayed access to healthcare in certain populations, and biological factors, where some anomalies develop or become detectable later in pregnancy. Research shows that access to timely antenatal care can lead to earlier detection and better management of anomalies. Still, barriers such as SES, geographic location, and healthcare resources can delay crucial screenings. This is particularly relevant in regions with less accessible healthcare, where screenings are often conducted later in pregnancy.^[19]^

The WHO recommends a minimum of eight antenatal visits to improve maternal and fetal outcomes and reduce perinatal mortality in high-risk pregnancies. Early and frequent prenatal contacts, combined with targeted screenings, could greatly enhance early detection and timely interventions.^[19]^ In the present study, despite the availability of advanced facilities and technology, early detection of anomalies did not occur.

A high percentage of pregnancies with congenital anomalies result in live births, with 61.9% being normal vaginal births and 35.7% cesarean sections, indicating positive outcomes. However, the stillbirth rate highlights the seriousness of certain anomalies and the need for prompt medical intervention. The significantly higher risk of preterm birth in fetuses with congenital anomalies is particularly concerning, aligning with global data showing preterm birth as a leading cause of neonatal mortality and morbidity.^[25,26]^ Comprehensive management strategies, including early intervention and targeted surveillance in high-risk pregnancies, can improve maternal and neonatal outcomes by reducing both the risks of preterm birth and stillbirth.^[20,27]^

Policymakers should launch awareness campaigns for expectant mothers about the benefits of early screening through scans to detect abnormalities. With the infant mortality rate (IMR) declining due to improved healthcare, the focus can shift to enhancing antenatal and intra-natal outcomes, thereby increasing the chances of mothers having healthy newborns.

Strengths and Limitations of the study

The primary strength of this study is the use of both retrospective and prospective components to understand the burden of congenital anomalies in an urban population. This approach enabled us to examine how anomalies present in terms of organ involvement, timing of detection, and associated maternal factors. The study also highlights the importance of routine ultrasound screening, which many women from underprivileged backgrounds may skip due to limited awareness of its role in identifying fetal anomalies.

At the same time, some limitations should be considered. The retrospective part of the study relied on the accuracy and completeness of medical records, which may have varied in quality and detail. Since the study was conducted in a single urban referral hospital, the findings may not apply to other regions or healthcare settings. The focus was solely on ultrasound screenings, and no additional diagnostic tools or confirmatory tests were used, which may have led to underreporting or misclassification of anomalies. In addition, certain maternal risk factors such as folic acid intake, exposure to harmful agents, or febrile illnesses during pregnancy were not assessed, though they can play a key role in fetal development.

While logistic regression was used to explore associations between maternal factors and congenital anomalies, multivariable logistic regression was not applied. This may limit the ability to fully control for confounding variables. Future studies with larger sample sizes should consider multivariable models for more robust risk factor analysis.

CONCLUSION AND GLOBAL HEALTH IMPLICATIONS

This study highlights the prevalence and patterns of congenital anomalies in antenatal mothers in urban Bangalore. Renal system anomalies are the most common, often detected later in pregnancy. Key factors linked to these anomalies include consanguinity and preterm conditions. Although most affected pregnancies lead to live births, the findings emphasize the need for routine early ultrasound screenings for effective detection and management. There is a clear requirement for improved early antenatal care, targeted screening protocols, better genetic counseling, and enhanced management of high-risk pregnancies. Future research should focus on comprehensive multicenter studies to better understand risk factors and improve outcomes.

Key Messages

1. Many fetal anomalies were detected only after 30 weeks of gestation, thereby limiting the scope for early intervention. 2) Renal system anomalies were the most common, comprising most cases found in routine ultrasound. 3) The findings reflect gaps in awareness and access to antenatal ultrasound screening among women from economically disadvantaged backgrounds indicating a need for targeted education and outreach.