European Journal of Cardiovascular Medicine

Gestational diabetes mellitus (GDM) is one of the most prevalent metabolic disorders complicating pregnancy, characterized by glucose intolerance first recognized during gestation [1]. Its rising incidence parallels global trends in obesity, sedentary lifestyles, and delayed childbearing, particularly in South Asian populations where the prevalence of GDM is notably higher [2]. While GDM is often transient, its implications on both maternal and neonatal health are substantial, often extending beyond the perinatal period [3].

Among the neonatal complications associated with GDM, hypoglycemia and macrosomia are of particular concern due to their frequency and potential for long-term consequences. Neonatal hypoglycemia, defined as blood glucose levels below 40 mg/dL within the first 24 hours of life, is a critical early complication arising from the abrupt interruption of transplacental glucose supply combined with persistent fetal hyperinsulinemia [4]. If undetected or inadequately treated, hypoglycemia may result in neurodevelopmental impairment, seizures, or even death. Macrosomia, commonly defined as birth weight exceeding 4,000 grams or the 90th percentile for gestational age, predisposes neonates to shoulder dystocia, birth trauma, and future metabolic derangements [5].

The intrauterine environment in GDM pregnancies is markedly altered by maternal hyperglycemia, which leads to excessive fetal insulin production—a key driver for both increased fetal adiposity and altered neonatal glucose regulation [6]. These pathophysiological mechanisms are well-understood; however, the clinical burden and predictors of these outcomes in specific regional populations remain under-investigated. South India, with its high burden of undiagnosed and poorly controlled GDM, presents a unique demographic for evaluating these neonatal risks [7].

Despite improvements in antenatal screening and glycemic monitoring protocols, the risk stratification of neonates born to GDM mothers remains inadequate in many clinical settings. Further, inconsistent documentation of outcomes such as early neonatal hypoglycemia and macrosomia complicates effective surveillance and intervention strategies [8]. Prior studies have identified various maternal risk factors, including elevated fasting plasma glucose, increased HbA1c levels, and excessive gestational weight gain, as contributing to these neonatal complications [9]. However, there exists a paucity of region-specific, prospective data linking maternal glycemic status to immediate neonatal outcomes.

The present study was undertaken to evaluate the correlation between maternal gestational diabetes and the risk of two key neonatal morbidities—hypoglycemia and macrosomia—in a tertiary care setting. By analyzing the incidence of these outcomes in neonates born to mothers with and without GDM, the study aims to generate actionable insights into risk prediction and early management. This investigation also seeks to emphasize the need for context-specific protocols to improve neonatal care and long-term child health in pregnancies complicated by GDM.

This prospective observational study was conducted in the Department of Obstetrics at Srinivasan Medical College and Hospital, Tamil Nadu, over a 12-month period from December 2023 to November 2024. The primary aim was to evaluate the correlation between maternal gestational diabetes mellitus (GDM) and the risk of neonatal hypoglycemia and macrosomia.

Study Design and Population

A total of 220 pregnant women aged 20 to 38 years were enrolled based on predefined inclusion and exclusion criteria. Participants were divided into two equal groups:

• GDM group (n = 110): Pregnant women diagnosed with GDM between 24 and 28 weeks of gestation using the International Association of Diabetes and Pregnancy Study Groups (IADPSG) criteria.
• Control group (n = 110): Age- and parity-matched pregnant women with normal glucose tolerance.

Exclusion criteria included pre-existing type 1 or type 2 diabetes mellitus, multiple gestations, known fetal anomalies, thyroid dysfunction, chronic hypertension, and corticosteroid exposure during pregnancy.

Data Collection

Maternal data were collected using a structured proforma and included demographic characteristics, body mass index (BMI), gestational age at delivery, glycemic control (HbA1c levels), and treatment modality (diet-controlled vs insulin-managed). Neonatal data collected at birth included birth weight, gestational age, APGAR scores, and venous blood glucose levels measured within the first two hours of life using a validated glucometer.

Neonatal hypoglycemia was defined as blood glucose <40 mg/dL within the first 2 hours post-delivery. Macrosomia was defined as birth weight ≥4,000 grams irrespective of gestational age.

Ethical Considerations

The study was approved by the Institutional Ethics Committee prior to initiation. Written informed consent was obtained from all participants after full disclosure of study objectives and procedures.

Statistical Analysis

All collected data were entered into Microsoft Excel and analyzed using IBM SPSS Statistics version 26. Continuous variables were expressed as mean ± standard deviation, while categorical variables were presented as frequencies and percentages. The independent t-test was applied to compare continuous variables between the two groups. Categorical variables were analyzed using the chi-square test or Fisher’s exact test, as appropriate. Binary logistic regression was performed to identify predictors of neonatal hypoglycemia and macrosomia within the GDM cohort. A p-value <0.05 was considered statistically significant. Odds ratios (OR) and 95% confidence intervals (CI) were calculated for major risk variables.

Table 1: Demographic Characteristics of Study Participants

Table 2: Neonatal Outcomes

Table 3: Association of HbA1c Levels with Neonatal Outcomes in GDM Group

Table 4: Logistic Regression – Predictors of Neonatal Hypoglycemia (GDM Group)

Table 5: Logistic Regression – Predictors of Macrosomia (GDM Group)

Fig 1: Incidence of neonatal hypoglycemia and macrosomia

The demographic characteristics between the GDM and control groups were largely comparable, although the mean BMI was significantly higher among the GDM group (26.4 ± 2.8 vs 24.9 ± 2.5; p = 0.002), suggesting a role of maternal adiposity in glycemic dysregulation.

Neonatal outcomes revealed a notably higher incidence of hypoglycemia in the GDM group (28.2%) compared to controls (9.1%), with the difference being statistically significant (p < 0.001). Similarly, macrosomia was observed in 23.6% of neonates born to GDM mothers versus only 7.3% in the non-GDM cohort (p = 0.004). Mean birth weight was also significantly elevated in the GDM group (3605 ± 410 g vs 3190 ± 375 g; p < 0.001), reinforcing the association between maternal hyperglycemia and excessive fetal growth.

Subgroup analysis of HbA1c levels showed a stepwise increase in the rates of both hypoglycemia and macrosomia with worsening glycemic control. Among mothers with HbA1c >6.5%, the incidence of neonatal hypoglycemia reached 41.7%, and macrosomia was observed in 38.9%.

Logistic regression analysis demonstrated that HbA1c >6.5% independently predicted both neonatal hypoglycemia (adjusted OR 3.62, 95% CI 1.88–6.97, p < 0.001) and macrosomia (adjusted OR 2.87, 95% CI 1.55–5.33, p = 0.001). Maternal BMI >25 also emerged as a significant predictor of macrosomia (adjusted OR 2.65, p = 0.004), whereas gestational age ≥39 weeks showed a nonsignificant trend.

These findings affirm the strong correlation between poor glycemic control in GDM and early neonatal complications, warranting vigilant prenatal and intrapartum monitoring.

Gestational diabetes mellitus (GDM) remains a pressing obstetric challenge due to its dual impact on maternal and neonatal outcomes. The current study was conducted to evaluate the association between GDM and the risk of two major neonatal morbidities: hypoglycemia and macrosomia.

The rationale for this investigation stemmed from the well-established pathophysiological link between maternal hyperglycemia and fetal hyperinsulinemia, which predisposes neonates to both hypoglycemia in the immediate postnatal period and excessive intrauterine growth [10]. However, regional variations in prevalence, diagnostic practices, and glycemic management warrant the generation of localized evidence to inform context-specific interventions.

In our study, neonates born to mothers with GDM had significantly higher rates of hypoglycemia (28.2%) and macrosomia (23.6%) compared to controls (9.1% and 7.3% respectively), aligning with findings from prior international and Indian cohorts [11,12]. For example, a 2022 study by Liu et al. reported neonatal hypoglycemia in 24.5% of GDM pregnancies, while Jindal et al. noted macrosomia in 21% of GDM births in a North Indian population [13,14].

Elevated maternal HbA1c (>6.5%) emerged as a robust predictor of both adverse outcomes in our study, suggesting that chronic hyperglycemia, rather than isolated spikes, plays a dominant role in fetal metabolic programming. These findings resonate with the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study, which showed a continuous relationship between maternal glucose levels and increased birth weight and neonatal morbidity [15].

The clinical implications are profound. Early identification of women at risk, intensive glycemic monitoring, and stricter intrapartum glucose control may reduce neonatal complications. Moreover, recognizing maternal BMI >25 as an independent predictor of macrosomia underlines the need for pre-pregnancy weight optimization and nutritional counseling.

This prospective observational study demonstrates a significant correlation between maternal gestational diabetes and the risk of neonatal hypoglycemia and macrosomia. The incidence of both complications was notably higher among neonates born to GDM mothers, particularly in those with poor glycemic control as indicated by elevated HbA1c levels. Logistic regression confirmed HbA1c >6.5% and maternal BMI >25 as independent predictors of adverse neonatal outcomes. These findings underscore the clinical importance of early diagnosis and rigorous glycemic management in pregnancies complicated by GDM. Enhanced antenatal surveillance, dietary counseling, and individualized treatment protocols could substantially mitigate neonatal risks. The study reinforces the critical need for context-specific management strategies in resource-limited settings and supports integrating metabolic indicators such as HbA1c into routine prenatal care to optimize perinatal outcomes.

Acknowledgement

The authors sincerely thank the Department of Obstetrics and the Neonatal Care Unit for their continuous support, infrastructure, and clinical cooperation throughout the study.

Conflicts of Interest

The authors declare no conflicts of interest related to this study.

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