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Published on: June 29, 2013
Gestational age-standardized neonatal growth patterns in adolescent pregnancy
Nazan Neslihan Doğan Kocabıyık1, Özgül Salihoğlu1
1University of Health Sciences, Bakırkoy Dr. Sadi Konuk Training Research Hospital, Department of Pediatrics, Division of Neonatology, Istanbul, Türkiye.
Insights
Neonatal size differences in adolescent pregnancies are primarily due to preterm birth, not intrinsic fetal growth restriction. Gestational age-adjusted analysis reveals minimal impact on overall fetal growth, with slight head circumference differences needing further study.
Area of Science:
- Obstetrics and Gynecology
- Neonatal Research
- Maternal-Fetal Medicine
Background:
- Adolescent pregnancy is associated with adverse neonatal outcomes.
- The underlying causes, whether prematurity or fetal growth restriction, require clarification.
Purpose of the Study:
- To determine if neonatal size variations in adolescent pregnancies stem from prematurity or intrinsic fetal growth restriction.
- To utilize gestational age-adjusted growth metrics for precise evaluation.
Main Methods:
- Retrospective study of 329 mother-infant dyads (111 adolescents, 218 adults).
- Neonatal anthropometrics standardized using INTERGROWTH-21st z-scores.
- Comparison of birth weight, length, head circumference z-scores, ponderal index, and growth asymmetry.
- Multivariable regression analysis adjusting for key covariates.
Main Results:
- Unadjusted analysis showed smaller neonates from adolescent mothers.
- Gestational age standardization eliminated significant differences in birth weight and length z-scores.
- A modest, cautious association was found for lower head circumference z-score in adolescent pregnancies.
- Adolescent pregnancy remained linked to preterm birth but not generalized growth impairment.
Conclusions:
- Adverse neonatal outcomes in adolescent pregnancy are mainly mediated by prematurity.
- Generalized fetal growth is not significantly impaired; head circumference differences require further investigation.
- Gestational age-standardized assessments are crucial for interpreting neonatal growth in adolescent pregnancies.
Objective:
To evaluate whether differences in neonatal size in adolescent pregnancy reflect prematurity or intrinsic fetal growth restriction using gestational age-adjusted growth metrics.
Study Design:
This retrospective single-center study included 329 mother-infant dyads (111 adolescents ≤19 years; 218 adults aged 20-35 years). Neonatal anthropometric measurements were converted into sex- and gestational age-adjusted z-scores using INTERGROWTH-21st standards. Birth weight, length, and head circumference z-scores, along with ponderal index, and growth asymmetry (HC_z - BW_z) were compared between groups. Multivariable regression analyses adjusted for gestational age, maternal smoking, neonatal sex, and maternal hemoglobin level.
Results:
In unadjusted analyses, infants born to adolescents had lower birth weight, length, and head circumference (all p < 0.001). After gestational age standardization, no statistically significant differences were detected in birth weight or length z-scores. A small nominal difference was observed in head-circumference z-score (Cohen's d = -0.25; nominal p = 0.031), which should be interpreted cautiously. Ponderal index and growth asymmetry did not differ. In multivariable analyses, adolescent pregnancy was not independently associated with birth weight or length z-scores but showed a modest association with lower head-circumference z-score (β = -0.35, 95% CI -0.61 to -0.08). Adolescent pregnancy remained independently associated with preterm birth (adjusted OR 2.39), while its association with low birth weight was attenuated.
Conclusion:
Adverse neonatal outcomes in adolescent pregnancy appear to be largely mediated through prematurity rather than generalized impairment in fetal growth. A modest difference in head-circumference z-score was observed, but its clinical relevance remains uncertain and requires confirmation in larger prospective studies. Gestational age-standardized assessment may improve the interpretation of neonatal growth patterns in adolescent pregnancy.
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