European Journal of Cardiovascular Medicine

The placenta, often termed the “tree of life,” is a critical organ for fetal survival and development. It facilitates essential physiological functions such as gas exchange, nutrient supply, waste elimination, and hormone production between the maternal and fetal circulatory systems. As pregnancy progresses, placental morphology and size dynamically change to accommodate the growing needs of the fetus. Among various ultrasonographic markers, placental thickness has gained prominence for its ease of measurement and potential predictive value in antenatal care [1]. Placental thickness measured through ultrasonography is a reliable, non-invasive parameter that reflects the health and function of the placenta. Deviations from the normative range of placental thickness have been associated with several pathological conditions. For instance, increased thickness may be indicative of gestational diabetes, fetal hydrops, or intrauterine infections, while reduced thickness is often seen in cases of intrauterine growth restriction (IUGR), preeclampsia, and placental insufficiency [2,3].

Despite advances in fetal imaging, the use of placental thickness as a predictive marker for adverse neonatal outcomes remains underutilized. A longitudinal approach, involving serial measurements of placental thickness across gestational ages, offers a more comprehensive understanding of its role in predicting fetal health. By establishing normograms for placental thickness at different gestational milestones, such studies can provide a robust framework for identifying deviations that may indicate potential risks [4]. Given the high maternal and neonatal morbidity in resource-limited settings such as Northeast India, there is a need to explore simple and affordable screening methods. Ultrasonographic placental thickness offers an accessible diagnostic tool that could play a pivotal role in early identification of high-risk pregnancies [5].

The general objective of this study was to determine the relationship between ultrasonographic placental thickness and the prediction of fetal outcomes among patients admitted to the Department of Obstetrics and Gynecology. Specifically, the study aimed to find a correlation between placental thickness measured at 32 and 36 weeks of gestation and various neonatal outcomes. Additionally, it sought to assess the utility of placental thickness as a simple, non-invasive test for predicting neonatal health, including the likelihood of adverse outcomes such as low birth weight, fetal distress, and the need for NICU admission.

Study settings: This prospective observational study was conducted in the Department of Obstetrics and Gynaecology at Government Medical College at Northeastern India, from June 2023 to December 2024.

Inclusion criteria: This study comprised women with singleton pregnancies with known last menstrual periods, gestational age ≥36 weeks, normal BMI, and those willing to provide informed consent.

Exclusion criteria: Women were excluded if they had high-risk obstetric or medical conditions such as diabetes, preeclampsia, or renal disease; fetal anomalies; multiple pregnancies; eccentric cord insertions; or placenta previa.

Sample size: The sample size was calculated using a standard formula based on a 10% prevalence of abnormal placental thickness, with a 95% confidence interval and a 5% margin of error using the standard formula described in World Health Organization manual [6]. After accounting for a 10% non-response rate and participant dropouts, 139 women were included in the final analysis.

Study Procedure: The study included pregnant women attending antenatal clinics and those admitted to the obstetric ward. Women were enrolled at 32 weeks of gestation and followed until delivery, with another placental thickness measurement at 36 weeks.Ultrasonographic evaluation was conducted using a 3.5 MHz curvilinear transducer. Placental thickness was measured perpendicularly at the level of the umbilical cord insertion, excluding the retroplacental myometrium. The readings were categorized as thin (<2.569 cm), normal (2.569–3.89 cm), or thick (>3.89 cm), based on gestational age-specific norms.

Data analysis and statistical analysis: Neonatal outcomes, including birth weight, Apgar scores, and NICU admission status, were recorded post-delivery. Statistical analysis was performed using SPSS software version 21.0 [7]. Categorical variables were compared using the Chi-square test, while continuous variables were evaluated with Student’s t-test or the Mann-Whitney U test, based on data distribution. A p-value of <0.05 was considered statistically significant.

Out of the 139 women enrolled, the average maternal age was 25.74 years. Placental thickness was measured at 32 and 36 weeks of gestation. At 32 weeks of gestation, the majority of participants (79.9%) had placental thickness within the normal range, while 12.2% exhibited thin placentas and 7.9% had thick placentas. [Table 1] Similarly, at 36 weeks, most women (84.9%) continued to have normal placental thickness, with 9.4% showing thin placentas and 5.8% having thick placentas. [Table 2]

Analysis revealed that neonates born to mothers with thin placentas had significantly lower birth weights (<2.5 kg) (p < 0.001). NICU admissions were also more frequent among these neonates (p < 0.001). Apgar scores at both 1 and 5 minutes were lower in the thin placenta group compared to the normal and thick placenta groups (p < 0.001). Moreover, fetal distress was more commonly observed in pregnancies with thin placentas at both gestational milestones (p < 0.001).

Conversely, pregnancies with thick placentas did not exhibit significant adverse outcomes. However, a few cases of gestational diabetes were observed in this group, although without corresponding increases in NICU admissions or poor neonatal outcomes.

Tables 1: Distribution of age Group

Tables 2: Distribution of Gravida

Tables 3: Distribution of Placental Thickness at 32 weeks

Tables 4: Distribution of Placental Thickness at 36 weeks

Tables 5: Distribution of Birth Weight

Tables 6: Distribution of Nicu Admission

Tables 7: Distribution of Fetal Distress

Tables 8: Distribution of NICU admission

Tables 9: Distribution of Fetal Distress

Tables 10: Distribution of APGAR SCORE

Tables 11: Distribution of APGAR SCORE

This study demonstrates a significant correlation between ultrasonographic placental thickness measured at 32 and 36 weeks of gestation and key neonatal outcomes, including birth weight, APGAR scores, fetal distress, and NICU admissions. The findings indicate that a thinner placenta (<2.569 cm) is consistently associated with adverse perinatal outcomes. Specifically, neonates with thinner placentas exhibited significantly lower birth weights, increased incidence of fetal distress, lower APGAR scores at both 1 and 5 minutes, and a higher likelihood of requiring NICU care. These observations suggest that reduced placental thickness may reflect placental insufficiency, characterized by impaired vascularization and compromised nutrient and oxygen exchange, ultimately leading to chronic fetal hypoxia.

The association between thin placentas and fetal distress was particularly noteworthy. At both gestational time points, a large proportion of fetal distress cases occurred in the thin placenta group. This aligns with findings from previous studies, such as those by Ohagwu et al. [2] and Hoddick et al. [8], who reported similar correlations between reduced placental thickness and compromised fetal oxygenation. Likewise, the significant relationship between placental thickness and birth weight observed in our study is consistent with the findings of Karthikeyan et al. [9] and Verma et al. [10], who demonstrated that thinner placentas were predictive of intrauterine growth restriction (IUGR) and lower fetal weight due to reduced placental function.

The study also showed that placental thickness has predictive value for neonatal morbidity requiring intensive care. At both 32 and 36 weeks, the majority of neonates admitted to the NICU had thinner placentas, reinforcing the clinical utility of this parameter in anticipating perinatal complications. A thin placenta may be indicative of long-standing hypoxia, which can result in conditions such as respiratory distress syndrome (RDS), hypoglycemia, and hypoxic-ischemic encephalopathy (HIE), as reported in earlier literature by Hasegawa et al. [11] and Gaccioli et al [12].

Interestingly, thick placentas (>3.89 cm) did not show a statistically significant correlation with adverse outcomes in this study. Most neonates in this group had normal birth weights and APGAR scores. While previous studies, including those by Basnet and Adhikari [13] and Banik et al.[14], have associated thick placentas with conditions like gestational diabetes mellitus (GDM), fetal macrosomia, and polyhydramnios, our study did not assess maternal metabolic status, which may explain the observed discrepancy.

From a clinical standpoint, placental thickness measurement is a practical and cost-effective tool that can be integrated into routine antenatal ultrasound protocols as stated by Hellman et al [15]. Unlike more complex investigations, such as Doppler studies, placental thickness can be easily assessed with basic ultrasound equipment, making it particularly valuable in resource-limited settings. The non-invasive nature and ease of measurement further enhance its applicability as a screening tool for fetal well-being, especially in pregnancies at risk due to hypertension, pre-eclampsia, or anemia.

Despite its strengths, this study has certain limitations. It focused primarily on immediate neonatal outcomes and did not explore the long-term developmental trajectory of neonates born with thin placentas. Additionally, maternal conditions like GDM, hypertensive disorders, and infections, which are known to influence placental morphology, were not comprehensively evaluated. The ultrasonographic measurement of placental thickness is inherently operator-dependent, introducing potential variability. Lastly, the study population was geographically limited, and ethnic or genetic factors influencing placental development were not assessed, which may affect the generalizability of the findings.

In conclusion, placental thickness is a valuable ultrasonographic marker with significant predictive utility for neonatal outcomes. Routine assessment, especially in high-risk pregnancies, can facilitate early identification of fetal compromise and inform timely clinical interventions to improve perinatal care and outcomes.

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