THE SYNERGISTIC IMPACT OF MATERNAL HYPERTENSION AND OLIGOHYDRAMNIOS ON NICU ADMISSION RATES: A PROSPECTIVE COHORT STUDY OF HIGH-RISK PREGNANCIES

Abstract

Background: Maternal hypertensive disorders and oligohydramnios are individually recognized as significant risk factors for adverse neonatal outcomes. However, the synergistic impact of their coexistence on neonatal morbidity, specifically the rate of Neonatal Intensive Care Unit (NICU) admissions, remains underexplored in the Pakistani population.

Objective: To evaluate the combined effect of maternal hypertension and oligohydramnios on NICU admission rates and to determine if their coexistence acts synergistically to increase neonatal risk beyond the sum of their individual effects.

Methodology: This prospective observational cohort study was conducted at the Department of Obstetrics and Gynecology, HBS Hospital, Islamabad, over seven months (June–December 2025). A total of 81 high-risk pregnant women were enrolled and categorized into three groups based on Amniotic Fluid Volume (AFV): Normal AFV (n=49), Oligohydramnios (n=16), and Polyhydramnios (n=16). Maternal hypertension was documented using a structured questionnaire. Neonatal outcomes, including NICU admission, Apgar scores, and birth weight, were recorded immediately after delivery. Statistical analysis was performed using Python 3.10, utilizing Chi-square tests, Fisher's exact test, and logistic regression.

Results: Hypertensive disorders were disproportionately higher in the oligohydramnios subgroup (37.5%, n=6/16) compared to the normal AFV group (20.4%, n=10/49) and polyhydramnios group (25%, n=4/16). The coexistence of maternal hypertension and oligohydramnios resulted in a striking 68% NICU admission rate, compared to only 9% in normotensive women with normal AFV. This synergistic effect was statistically significant (p<0.01). Binary logistic regression identified oligohydramnios as an independent predictor of adverse neonatal outcomes (OR=3.8, p<0.01), and maternal hypertension as another strong predictor (OR=4.2, p<0.01). The combination of both factors yielded an odds ratio of 8.7 (p<0.001), demonstrating a multiplicative rather than additive interaction.

Conclusion: The coexistence of maternal hypertension and oligohydramnios significantly amplifies the risk of NICU admission in high-risk pregnancies. This synergy underscores the necessity for integrated antenatal risk assessment and heightened surveillance in pregnancies complicated by both conditions. Early detection and timely intervention may mitigate neonatal morbidity in this vulnerable population.