This study analyzed the socio-demographic factors, maternal and obstetric factors and behavioral factors of mothers with delivery of low birth weight baby. In response to educational status of mother, our study found that educational status was significantly associated with low birth weight in which illiterate mother were more prone to give birth to LBW baby as compared to literate mothers. This finding is in line with the studies conducted in Nepal, Ethiopia and Ghana which showed that illiterate mothers or mothers having lower level of education were more prone to deliver LBW baby as compared to literate mothers.^(16,20,21) Therefore, it would be beneficial to improve the maternal educational status in order to prevent the delivery of low birth weight baby. However, no statistical significant association was observed between mother’s educational status and LBW baby in the study conducted in Bangladesh.⁽²²⁾ The study population in Bangladesh was relatively homogenous in terms of education, so the variation in birth outcomes between educated and uneducated mothers could be less pronounced. This homogeneity may have reduced the ability to detect significant differences in LBW rates based on education.

Our study observed a significant association between per capita income of family with LBW where the mothers whose family is below the poverty line tend to give birth to more LBW baby as compared to the mothers whose family is above poverty line. Similar findings was observed in a study conducted by Bhaskar et al. that revealed significant association between per-capita income and LBW.⁽²³⁾ Economic status is found to be relatively well established factor for LBW baby as it is linked with overall care for the mothers during pregnancy which directly impacts the birth outcome. The present study identified parity as a significant determinant of low birth weight (LBW), with primiparous women being at a five-fold increased risk of giving birth to LBW babies compared to multiparous women. These findings are supported by studies conducted in a tertiary teaching hospital in Kathmandu, Nepal and Tamale Metropolis.^(12,24) Similarly, a systematic review of maternal risk factors for LBW, including a 10-year study from Korea, found that LBW rates were higher among primiparous women, which aligns with our results.⁽²⁵⁾ The first-time mothers (primiparous women) might be at higher risk of giving birth to LBW baby due to factors like lack of experience in prenatal care, poorer nutritional status, or anxiety during pregnancy. However, these findings contradict those from studies conducted in Tribhuvan University Teaching Hospital (TUTH) of Nepal and selected hospitals of Indore, India, where no significant association was observed.^(26,27)

In this study, indicating that mothers with lower hemoglobin levels <11 mg/dl had more than six times the risk of giving birth to low birth weight (LBW) babies compared to those with hemoglobin levels ≥11 mg/dl. These findings are consistent with a study conducted in Ethiopia, which found that established a link between maternal anemia and LBW.⁽²⁸⁾ Other studies, including those by Kayastha et al., Sah et al., Bater et al. and Arabzadeh et al. also reported a significant association between low maternal hemoglobin levels and the incidence of LBW babies..^(12,29–31) However, there are studies, such as those conducted by Shrestha et al. in Lumbini Provincial Hospital and Bhaskar et al. in Eastern Nepal, that contradict these findings, as they observed no significant association between maternal hemoglobin levels and LBW births.^(16,23) Reduced hemoglobin levels hinder the mother’s capacity to deliver adequate oxygen and nutrients to the fetus, while also affecting her own oxygen levels and the formation of the placenta. This leads to a sustained lack of oxygen (fetal hypoxia) and inadequate nutrient supply to the fetus, which impedes healthy weight gain. Ultimately, these factors contribute to poor birth outcomes, such as low birth weight (LBW).⁽³²⁾

Preterm birth is widely recognized as a significant risk factor for low birth weight (LBW), as babies born before 37 weeks of gestation are often not fully developed, leading to lower birth weights. In our study, women who delivered preterm were found to be 8 times more likely to have an LBW baby compared to those who carried their pregnancies to full term. The findings from our study are comparable to those reported in several other studies. For instance, research by Bansal et al., Shrestha et al., Chhetri et al. and Sutan et al. also identified preterm delivery as a significant predictor of LBW.^(8,16,33,34) Thus, the consistent findings across multiple studies highlight the importance of preventing preterm births to reduce the incidence of LBW and improve overall neonatal health outcomes.

Our study found that being underweight, with a pre-pregnancy weight below 45 kg, is significantly associated with higher odds of giving birth to a low birth weight baby. Similar findings were reported by Abubakari et al. in Tamale Metropolis, Sutan et al. in Malaysia, Dutta et al. at Assam Medical College in India, Devaguru et al. in Telangana, India, Andemariam et al. in Asmara and Tadese et al. in Ethiopia, all of whom identified a significant association between LBW and maternal pre-pregnancy weight.^(24,34–37) In contrast, studies by Mulu et al. and Wanode et al. found no significant association between maternal pre-pregnancy weight and the likelihood of delivering a LBW baby.^(20,27) This divergence in findings highlights the complexity of maternal health and its influence on neonatal outcomes, underscoring the need for further investigation into the role of pre-pregnancy weight in different demographic and geographic settings.

Presence of chronic medical illness among mother has an increased odds of giving birth to LBW baby in our study. This finding aligns with results from several studies, such as those by Pal et al. in West Bengal, K.C. et al. in Dang, Gebremedhin et al. in Northern Ethiopia, Mulu et al. in Addis Ababa, Ethiopia and Sutan et al. in Malaysia, which identified co-morbid conditions like hypertension as significant risk factors for LBW neonates.^{(20,34,38–40)} The biological reasoning behind this association likely stems from how hypertension affects blood flow and nutrient transfer between the mother and the fetus. In hypertensive pregnancies, reduced uteroplacental blood flow can lead to fetal growth restriction, thereby increasing the risk of LBW.⁽⁴¹⁾ Presence of medical illness during pregnancy was found to be significantly associated with LBW babies in our study which is in accordance with other studies conducted by Pal et al, Bhaskar et al., Toru et al. and Andemariam et al. These studies consistently found that mothers who experienced medical illnesses during pregnancy had a higher risk of delivering LBW infants compared to those who did not face any medical complications during their pregnancy.^{(23,38,42,43)} Maternal illnesses can result in poor pregnancy outcomes by affecting the mother’s overall health, nutritional status, and the ability to carry the pregnancy to full term which increases the likelihood of preterm birth, another significant risk factor for LBW.

The dietary habit of a mother during pregnancy has a significant role in the maintenance of the proper weight of newborn babies. The present study identified that vegetarian mothers had a higher risk of delivering low birth weight (LBW) babies compared to non-vegetarian mothers. This finding is in line with the study from hospital based study in Nepal conducted by Sah et al. and Canada conducted by Zulyniak MA et al. both of which reported that a plant-based diet was associated with lower birth weight.^(29,44) Similarly, another study by Koirala et al. in Nepal also found an increased risk of LBW among vegetarian mothers, though the association was not statistically significant.⁽⁴⁵⁾ Animal-based foods, which are high in iron and essential hemopoietic nutrients such as vitamin B12 and folic acid, contribute to raising hemoglobin levels in pregnant women.⁽⁴⁶⁾ Adequate intake of these nutrients reduces the likelihood of low birth weight in newborns by supporting proper fetal growth.

Smoking and alcohol consumption during pregnancy are an established significant risk factors for low birth weight (LBW) babies, adversely affecting both maternal and fetal health. This present study revealed that both smoking and alcohol consumption during pregnancy posed a greater risk of giving birth to LBW babies. These findings are supported by systematic review and meta-analysis of 55 cohort studies from 1986 to 2020 conducted by Kun Di et al. and an umbrella review conducted by Arabzadeh et al.^(31,47) Other studies such as those conducted by Kayastha et al. in Nepal, Taywade et al. in Wardha district of India and Devaguru et al. in Telangana, India also found the results that are consistent to the results of our study.^(12,36,48) Despite being an established risk factors for pregnancy, our study may not hold the statistical power to predict the outcomes since the number of smokers and alcohol consumers were very less in our study.

This study has several limitations. As the study is of retrospective nature, participants may fail to remember the factors that have happened in the past. Thus, it may result in recall bias. The study was conducted in a single government hospital within the Kathmandu Valley so the findings primarily reflect mothers delivering in similar institutional settings and may not capture all community-level variations. Since the data were collected using face-to-face interviews, it might have resulted in social desirability bias in some self-reported behaviors like dietary practices, smoking and alcohol consumption. The relatively small number of participants who reported smoking or alcohol consumption also limited the statistical power to detect strong associations with these factors. Despite these limitations, the study provides robust evidence on modifiable maternal and socio-demographic determinants of low birth weight, which can inform both hospital-based and community-level interventions in Nepal.