Correlation of Severity of Maternal Hypertension and Birth Weight of Neonates- A Longitudinal Study

Abstract

Introduction: Pregnancy Induced Hypertension (PIH) can lead to intrauterine growth restriction resulting in Low Birth Weight (LBW) neonates. LBW remains a significant cause of under-five mortality in India and Asia. Aim: To calculate the prevalence of PIH and to study the correlation between Birth Weight (BW) of neonates and severity of maternal hypertension; and compare the incidence of neonatal morbidities across varying severity of maternal hypertension. Materials and Methods: A longitudinal study was conducted among 153 pregnant mothers, diagnosed with PIH. They were classified into mild {Systolic Blood Pressure (SBP) ≥140- 149 mmHg or Diastolic Blood Pressure (DBP) ≥90-99 mmHg}, moderate (SBP ≥150-159 mmHg or DBP ≥100-109 mmHg) and severe (SBP ≥160 mmHg or DBP ≥110 mmHg) hypertension. A total of 142 neonates, born to PIH mothers, were included. The neonates were followed-up for seven days to check for early neonatal outcomes and deaths. Correlation between maternal blood pressure (systolic and diastolic) and BW of the neonates was assessed using Pearson’s correlation coefficient (r). Binary Logistic Regression (BLR) was performed to analyse the impact of confounders on BW. Results: The prevalence of PIH was 7.76% (153/1972). The mean BW of neonates born to mothers with moderate (2.435 kg) and severe hypertension (2.342 kg) was significantly lower than that of neonates born to mothers with mild hypertension (2.828 kg) (p<0.00001). 1SD increase in SBP resulted in 0.245 kg decrease in BW, while an 1SD increase in DBP resulted in 0.312 kg decrease in BW. After accounting for confounders using BLR, maternal DBP still had a significant negative correlation with BW (r=-0.663; p<0.001). The incidence of prematurity (p<0.0001), small for Gestational Age (GA) (p=0.0283), Respiratory Distress (RD) (p=0.002), Neonatal Hyperbilirubinemia (NNH) (p=0.033) and Neonatal Intensive Care Unit (NICU) admissions (p=0.003) were significantly higher among neonates born to mothers with moderate and severe hypertension than those born to mothers with mild hypertension. Three neonatal deaths (all due to perinatal asphyxia) were observed in this study and there was no statistical significance with respect to deaths across neonates of the three groups (p=0.219). Conclusion: Maternal DBP had a significant negative correlation with BW. The mean BW of neonates born to mothers with severe hypertension was significantly lower compared to those born to mild hypertension.