Birth Weight of Neonates in Primiparous Mothers across Different Age Groups: A Cross-Sectional Study

Document Type : Original Article

Authors

1 Medical student, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran.

2 Associate Professor, Department of Pediatrics, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran.

3 Assistant Professor, Department of Community Medicine, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran.

10.22038/ijogi.2025.71977.5686

Abstract

Introduction: Birth weight is one of the key indicators of neonatal health and a strong predictor of growth, survival, and health in infancy and childhood. Maternal age is considered an important determinant of pregnancy outcomes, and various studies have shown that pregnancies at younger and older ages may be associated with an increased risk of low birth weight. Accordingly, the present study was conducted with aims to compare the birth weight of newborns among primiparous mothers in different age groups.
Methods: In this descriptive-analytical study, the medical records of 200 primiparous mothers with singleton pregnancies were selected through convenience sampling and evaluated in three age groups: under 18 years, 18–35 years, and over 35 years, who had referred to the hospitals affiliated with Islamic Azad University of Tehran during 2021–2022. Required background information such as gestational age, baby's gender, mother's age, mother's body mass index, family income, mother's and father's education, and newborn's birth weight were entered as dependent variables in the prepared checklist. Data were analyzed using SPSS statistical software (version 26) and the t-test, ANOVA, and multiple linear regression analysis. P<0.05 was considered significant.
Results: The highest mean birth weight (3635.7 g) was observed in age group 18-35 years which indicated a more favorable situation in terms of birth weight in this group. The lowest mean birth weight (2360 g) was for mothers under 18 years of age, which is medically considered to be at risk for low birth weight. Mothers over 35 years of age also gave birth to babies with lower birth weights (mean 2551.5 g) than the middle group, which could be related to the risk factors in older age (95% CI: 2718.61-2953.69, p≤0.001). According to the results of the multiple linear regression test, there was a significant relationship between birth weight and maternal age, gestational age, and gender (p<0.05).
Conclusion: Maternal age, gestational age, and the gender of the baby significantly affect birth weight. Specifically, babies born to mothers over 35 years of age have lower birth weights compared to babies born to younger mothers, especially those under 18 to 35 years of age.

Keywords

Main Subjects

References

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The Iranian Journal of Obstetrics, Gynecology and Infertility
Volume 28, Issue 7
September 2025
Pages 34-44

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