Outcomes and Risk Factors in Low Birth Weight Neonates

Low weight at birth or low birth weight, meaning weight less than 2,500 grams at birth, is one of the common problems in neonatal health care.¹ It is widely regarded as an important predictor of maternal and antenatal care service provision.¹ Low-weight infants are more at risk of illness and complications compared to their normal-weight counterparts.² The infants are at risk specifically of infections, slow growth rate, feeding difficulty or refusal to feed at all, and long-term developmental delays.³ Low weight at birth in the vast majority of cases is caused by prematurity or intrauterine growth retardation, both of these being precipitated by an interplay of maternal, fetal, and environmental factors.⁴ As a result of these predispositions, low weight at birth is an important cause of neonatal morbidity and mortality across the world and is hence an important focal point in maternal and child health projects.⁵

 

There are several maternal and obstetric factors known to determine risk of LBW, amongst which advanced maternal age and maternal anemia are of great significance.⁶ Females above the age of 35 are at additional risk to develop issues such as poor functioning of the uterus and placenta and hence might limit delivery of oxygen and nutrients to the developing embryo and thus lead to restraint in growth and predispose to preterm delivery and thus lead to low weight at delivery.⁷ Maternal anemia also has a significant correlation with undesirable neonatal outcomes. Lack of hemoglobin in the mother reduces oxygen-carrying capacity of the blood and thus leads to suboptimal delivery of oxygen to the embryo and impairs in-utero growth.⁶ Anemia has been linked to lethargy in the mother as well and risk of preterm labor and pregnancy-specific pathology and thus add to the risk of low weight at delivery.⁶

 

Outcomes in low birth weight babies are mostly severe and can cause immediate and long-lasting adverse problems. For very severe cases, intrauterine growth retardation has the possibility of culminating in stillbirth.⁸ For these preterm infants who are able to survive, hospitalization in the neonatal intensive unit (NICU) is necessary due to complications such as respiratory issues, failure to maintain body temperature, feeding problems, and a higher chances of developing infections.⁹ These health issues are highly expensive in terms of healthcare and require specialized hospital services. Another common is low birth weight infant have very low Apgar score at delivery reflecting difficulty in adapting to life outside the womb such as poor breathing, poor muscle tone or poor reflexes.¹⁰ Despite having made it through the neonatal period, these children are vulnerable to long-lasting complications like stunted growth, slow maturation, and an increased risk of developing long-lasting chronic conditions in the long run.

 

Agarwal G. identified advanced maternal age in 33.33% of mothers and maternal anemia in 47.61% as major risk factors for low birth weight neonates.¹¹ In comparison, Desta M. reported outcomes among low birth weight infants, including low Apgar score in 42% of cases, stillbirth in 35.4%, and NICU admission in 22.6%.¹²

 

Conducting this study in Mardan is important since low birth weight remains an important public health problem in the province with limited evidence on contributing causes and consequences. The population in Mardan is varied with varying maternal education awareness level, nutrition status, and utilization of health services and each has the potential to influence neonatal health. With an identification of risk factors such as advanced maternal age and anemia in the mother and consequences such as stillbirth and admission to the NICU and low Apgar score, the study will be in a position to provide locally relevant evidence to guide preventative measures.

This cross-sectional study was conducted in the Gynae A Ward of Mardan Medical Complex and Teaching Hospital, Mardan, from 10^thJune 2025 to 10^thNovember 2025. A sample of 105 participants was obtained, with the size determined using the WHO sample size calculator, keeping a 95% confidence level, an 8% margin of error, and an expected frequency of NICU admissions in low birth weight neonates at 22.6%.¹² Non-probability consecutive sampling was applied for participant selection.Prior approval was secured from the institutional ethics committee (No: 786/BKMC, Dated 06-05-2025) as well as the research department of CPSP Karachi. Mothers who fulfilled the inclusion criteria were invited to participate after providing written informed consent, with full details of the study explained and confidentiality assured. Neonates with major birth defects such as congenital heart malformations or neural tube defects, those with severe infections at birth, or those weighing less than 1,000 grams were included. Women with multiple pregnancies and those with congenital anomalies were excluded. Low birth weight was defined as any neonate weighing less than 2,500 grams within the first 24 hours of life, measured on a calibrated digital scale. Demographic details were documented using a structured proforma. Each neonate was assessed in the presence of a consultant gynecologist with more than five years of post-fellowship experience. Mothers delivering neonates with low birth weight were evaluated for risk factors, particularly anemia and advanced age, and neonatal outcomes were documented accordingly.

 

Advanced maternal age referred to pregnancies in women older than 35 years. Maternal anemia was considered when hemoglobin levels were recorded below 11 g/dL during pregnancy. Stillbirth was taken as intrauterine fetal death confirmed by ultrasound with absent cardiac activity. NICU admission was noted when a neonate required specialized postnatal care due to compromised health. A low Apgar score was considered when the five-minute score was less than 7 on the 10-point scale that assesses respiration, heart rate, reflexes, muscle tone, and color.

 

Data were analyzed using SPSS version 23. The distribution of continuous variables was assessed with the Shapiro–Wilk test. Results were reported as mean with standard deviation or median with interquartile range, depending on distribution. Categorical datawere presented as frequencies and percentages. Potential effect modifiers such as maternal age, gestational age, BMI, and comorbidities were managed through stratification. Post-stratification analysis was conducted using the chi-square test or Fisher’s exact test, with a p-value of less than 0.05 considered statistically significant.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table-III: Association of Demographics with Risk Factors and Neonatal Outcomes

*Fischer Exact Test

The present study aimed to evaluate the outcomes and risk factors in low birth weight neonates, revealing several important clinical findings that warrant discussion. The significant association between advanced maternal age and mothers over 30 years (p<0.001) aligns with established biological mechanisms, as maternal aging is associated with decreased oocyte quality, increased chromosomal abnormalities, and compromised placental function, all of which contribute to adverse pregnancy outcomes including low birth weight. The strong correlation between elevated maternal BMI (>25 kg/m²) and advanced maternal age (p<0.001) reflects the physiological changes that occur with aging, including metabolic alterations, insulin resistance, and hormonal fluctuations that predispose to weight gain and altered body composition.

 

The high prevalence of maternal anemia (46.7%) in this cohort is particularly concerning, as iron deficiency during pregnancy directly impacts fetal growth through reduced oxygen-carrying capacity and impaired placental development, leading to intrauterine growth restriction and subsequent low birth weight. The substantial rate of low Apgar scores (41.9%) suggests significant perinatal compromise, likely resulting from the cumulative effects of maternal risk factors on fetal well-being, including reduced uteroplacental blood flow and compromised fetal oxygenation during labor and delivery. The elevated stillbirth rate (35.2%) indicates severe fetal compromise, potentially due to placental insufficiency, maternal vascular disease, or fetal growth restriction associated with the identified risk factors. Interestingly, the relatively lower NICU admission rate (21.9%) compared to other adverse outcomes may reflect either effective immediate postnatal management or potentially underutilization of intensive care resources.

 

The observed prevalence of advanced maternal age (32.4%) in our cohort aligns with findings from Tessema et al. 13 who identified maternal age less than 20 years as a significant risk factor across Sub-Saharan Africa, though our study focused on the opposite end of the age spectrum. Similarly, Habeeb et al. 14 reported significant associations with maternal age (p<0.001), corroborating our findings regarding age as a critical determinant of birth weight outcomes. The strong association between elevated maternal BMI and advanced maternal age (p<0.001) in our study finds partial support in the work of Khazaei et al. 15 who identified maternal BMI less than 18.5 as a protective factor (OR=0.3, 95% CI: 0.1-0.9), suggesting that both extremes of maternal weight status impact fetal growth, though through different mechanisms.

 

Our finding of 46.7% prevalence of maternal anemia closely mirrors the results reported by Maheswari& Sharma 16 who found anemia in 31.3% of mothers with low birth weight neonates, and Habeeb et al. 14 who reported anemia in 62.7% of cases. This consistency across different geographical regions underscores the global significance of maternal anemia as a modifiable risk factor. However, our study's lack of significant association between diabetes (27.6% prevalence) and adverse outcomes contrasts with the findings of Ali et al. 17 who identified pregnancy-induced hypertension in 29.2% of cases as a significant maternal risk factor, and Shaohua et al. 18 who reported hypertension as having an adjusted odds ratio of 1.94 (95% CI: 1.39-2.74) for low birth weight.

 

The high rate of low Apgar scores (41.9%) observed in our study is comparable to the respiratory complications reported by Ali et al. 17 who found respiratory distress in 82% of low birth weight neonates, suggesting similar degrees of perinatal compromise. Our stillbirth rate of 35.2% is substantially higher than the mortality rates reported in other studies, including Ali et al. 17 who reported 52% mortality but primarily in very low birth weight categories, and Yasmin et al. 19 who found 52% mortality specifically in extremely low birth weight neonates. This discrepancy may reflect differences in healthcare infrastructure, access to emergency obstetric care, or variations in study population characteristics, as our study included all low birth weight categories rather than focusing on specific weight ranges.

 

The relatively low NICU admission rate (21.9%) in our study contrasts sharply with the findings of Maheswari& Sharma 16 who reported morbidities in 92.1% of low birth weight neonates, and Adhikari et al. 20 who found sepsis in 96% and jaundice in 87% of cases. This difference may indicate either effective community-based management strategies, limited NICU capacity, or potentially different criteria for admission, as suggested by the varying healthcare delivery models across different settings. The absence of significant associations with gestational age in our study differs from multiple reports including Khazaei et al. 15 who found gestational age less than 37 weeks had an odds ratio of 3.8 (95% CI: 0.9-6.1), and Shaohua et al. 18 who reported preterm birth as a key determinant with AOR of 0.15 (95% CI: 0.10-0.24). This variation may reflect our study's focus on term low birth weight cases or differences in gestational age assessment methods, highlighting the importance of standardized measurement protocols in comparative research.

 

Several limitations must be acknowledged when interpreting these results. This single-center study may limit the generalizability of findings to broader populations, as institutional practices, patient demographics, and resource availability may differ significantly across healthcare settings. The relatively small sample size of 105 participants may have been insufficient to detect statistically significant associations with less prevalent risk factors, potentially leading to type II errors and underestimation of certain relationships. The cross-sectional design precludes establishment of causal relationships between identified risk factors and outcomes, limiting our ability to determine temporal sequences and confounding variables.

Our study has concluded that outcomes and risk factors in low birth weight neonates are significantly influenced by maternal demographic characteristics, particularly advanced maternal age and elevated BMI, which emerged as the primary determinants of adverse outcomes in this population. The high prevalence of maternal anemia and substantial rates of neonatal complications, including low Apgar scores and stillbirth, underscore the critical importance of comprehensive maternal health assessment and targeted interventions during the antenatal period.

 

Conflict of interest:  None

Disclaimer:  None

Acknowledgments: Our heartfelt gratitude goes to the department’s healthcare staff, whose consistent dedication and careful handling of patient documentation and records played a vital role in supporting this work.

 

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