Korean J Perinatol.  2014 Dec;25(4):276-283. 10.14734/kjp.2014.25.4.276.

Advanced Maternal Age and Weight at Birth in Newborn Infants: Distribution and Clinical Characteristics

• Cho KH
• Jo HS
• Cho SI
• Eom YA
• Rhie S
• Lee KH

• KMID: 2281145
• DOI: http://doi.org/10.14734/kjp.2014.25.4.276

Abstract

PURPOSE
This study aimed to compare the neonatal outcome by quantifying the effect of maternal age on low birth weight (LBW).
METHODS
We reviewed the medical records of 12,742 newborn infants born at CHA Bundang Medical Center from January 2009 to December 2013. Infants were compared after being categorized by the following 4 maternal age groups - <25 years (N=343), 25-34 years (N=8,573), 35-39 years (N=3,186), > or =40 years (N=640). Statistical analysis included use of logistic regression models with likelihood ratio tests for interaction effects.
RESULTS
Incidence of perinatal complications tended to increase significantly with maternal age - gestational diabetes mellitus (GDM; P<0.001), pregnancy induced hypertension (PIH; P=0.019), placenta previa (P<0.001), and cesarean section (P<0.001). Compared to the age group of 25-34 years (reference group), no significant differences were found in age group of 35-39 year [odds ratio (OR)=0.945, 95% confidence interval (CI) 0.847-1.056, P=0.319] and > or =40 years (OR=0.841, 95% CI 0.671-1.056, P=0.136) for LBW. After adjusted by gestational age, incidence of in vitro fertilization (IVF), and perinatal complications, maternal age was not found to be an independent risk factor for LBW (OR=0.847, 95% CI 0.730-0.982, P=0.028 for 35-39 years, and OR=0.652, 95% CI 0.481-0.884, P=0.006 for > or =40 years).
CONCLUSION
Although incidence of perinatal complications tends to increase with age, neonatal outcome of age group of > or =35 years measured by incidence of LBW infants was not unfavorable compared to the reference group. The result suggests that the thorough prenatal care may be more important than the maternal age itself.

Keyword

Maternal age; Low birth weight; Gestational age

MeSH Terms

Cesarean Section
Diabetes, Gestational
Female
Fertilization in Vitro
Gestational Age
Humans
Hypertension, Pregnancy-Induced
Incidence
Infant
Infant, Low Birth Weight
Infant, Newborn*
Logistic Models
Maternal Age*
Medical Records
Parturition*
Placenta Previa
Pregnancy
Prenatal Care
Risk Factors

Figure

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  Fig. 1. The progress in proportion of births according to maternal age in CHA Bundang Medical Center from 2009-

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  Fig. 2. Distribution of gestational age of infants in relation to maternal age (no significant linear correlation exist, R2= 0.0015).

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  Fig. 3. Distribution of birth weight of infants in relation to maternal age (no significant linear correlation exists, R2= 0.0038).

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