Maternal Age and Outcomes in Very Low Birth Weight Singleton Infants

Abstract

Maternal age is an established determinant affecting pregnancy and neonatal outcomes. Its particular role in very low birth weight (VLBW) singleton infants, those born with a weight below 1,500 grams, is an area of continued study. This article explores the complex interaction between maternal age and neonatal outcomes for this at-risk population. Younger mothers (less than 20 years) and advanced maternal-age mothers (35 years and above) have unique risk profiles, ranging from obstetric complications to neonatal morbidities and survival. The biological, social, and healthcare-related determinants of various maternal age groups are responsible for differences in neonatal outcomes like mortality, intraventricular hemorrhage, bronchopulmonary dysplasia, necrotizing enterocolitis, and long-term neurodevelopmental impairments. An appreciation of these relationships is critical for the customization of perinatal care strategies and the maximization of neonatal health in VLBW neonates. This review synthesizes existing evidence, identifies knowledge gaps, and stresses the value of individualized maternal-fetal care throughout the range of maternal ages.

Introduction

Maternal age has come increasingly to be regarded as an important determinant of pregnancy outcome, especially where high-risk pregnancy is concerned. As with changing societal trends — such as delayed childbearing and adolescent pregnancy — the provision of obstetric practice has been transformed in terms of maternal age. Perinatal outcomes are directly affected by these changes, notably in susceptible groups like VLBW infants. VLBW infants, those with birth weights below 1,500 grams, are confronted with a range of medical issues and are extremely vulnerable to poor outcomes.

The impact of maternal age on outcomes of VLBW infants is multifaceted and multifactorial. Young and old mothers possess unique biological, socioeconomic, and healthcare-related risk factors that can influence neonatal health trajectories. This article explores these age associations, discussing how maternal age affects the survival, morbidity, and long-term outcomes of VLBW singleton infants.

Maternal Age Categories and Population Trends

In examining maternal age and its associations with VLBW outcomes, researchers commonly divide mothers into three groups:

• Adolescent mothers (under 20 years)

• Optimal reproductive age mothers (20 to 34 years)

• Advanced maternal age (AMA) mothers (35 years and older)

Both adolescent and AMA pregnancies have been associated with increased risks for preterm delivery, intrauterine growth restriction (IUGR), and obstetric complications. These risks are magnified in VLBW infants, where even subtle shifts in maternal health can drastically affect neonatal survival and development.

Adolescent Mothers: Unique Challenges

Adolescents often experience pregnancies complicated by:

• Limited prenatal care

• Poor nutritional status

• Higher rates of preterm labor

• Increased incidence of infections

Social factors, including unstable family support, lower socioeconomic status, and limited health literacy, further compound these risks.

Advanced Maternal Age Mothers: Biological and Obstetric Risks

Older mothers face their spectrum of risks, including:

• Declining uteroplacental function

• Higher rates of hypertensive disorders and gestational diabetes

• Increased likelihood of multiple gestation (though excluded here by focusing on singletons)

• Higher cesarean delivery rates

These factors are highly relevant to VLBW outcomes, as preterm birth and fetal growth restriction are more frequent in this age group.

Neonatal Survival and Mortality by Maternal Age

Several large cohort studies have examined the relationship between maternal age and survival rates in VLBW infants. While findings vary, some consistent trends have emerged:

• Adolescent Mothers and Neonatal Survival: Despite the higher rates of preterm birth among adolescent mothers, some studies suggest that VLBW infants born to younger mothers may have slightly better survival rates than those born to older mothers. This could be attributed to healthier placental function and fewer preexisting maternal health conditions in teenagers.

• Advanced Maternal Age and Mortality Risk: Infants born to older mothers tend to have higher mortality rates, especially when maternal comorbidities or pregnancy complications (e.g., preeclampsia, placental insufficiency) are present. This age group’s increased risk of delivering growth-restricted infants further contributes to elevated mortality.

Neonatal Morbidities: Influence of Maternal Age

VLBW infants are at heightened risk for a range of morbidities, many of which are influenced by maternal age. These include:

Intraventricular Hemorrhage (IVH)

• Adolescents: Infants born to adolescents tend to show moderate rates of IVH, likely due to the higher incidence of spontaneous preterm labor with limited prenatal corticosteroid exposure.

• Older Mothers: VLBW infants of AMA mothers may be at greater risk of severe IVH due to placental insufficiency and associated hemodynamic instability.

Bronchopulmonary Dysplasia (BPD)

• Adolescents: BPD risk appears comparable between adolescent and optimal-age mothers, though it can be exacerbated by inadequate antenatal steroid coverage in adolescent pregnancies.

• Older Mothers: Advanced maternal age is associated with higher rates of pregnancy-induced hypertension and preeclampsia, conditions linked to fetal lung immaturity and BPD development.

Necrotizing Enterocolitis (NEC)

• Adolescents: The rates of NEC in VLBW infants born to adolescent mothers do not significantly differ from those of older mothers, but social factors (like early breastfeeding discontinuation) can impact gut health.

• Older Mothers: Infants of older mothers may experience slightly higher NEC risk due to impaired placental function and altered fetal gut development.

Retinopathy of Prematurity (ROP)

• Adolescents and Older Mothers: ROP rates appear relatively consistent across age groups, though subtle differences may exist related to oxygen exposure practices and neonatal care variation.

Neurodevelopmental Outcomes in VLBW Infants by Maternal Age

The impact of maternal age extends into the neurodevelopmental realm, particularly for VLBW infants who survive to early childhood.

• Adolescent Mothers: Cognitive and developmental outcomes in VLBW infants born to adolescent mothers appear moderately impaired, with some evidence suggesting that home environment and educational resources contribute as much as biological factors. Maternal immaturity and socioeconomic instability often create suboptimal environments for early cognitive development.

• Advanced Maternal Age Mothers: In contrast, VLBW infants born to older mothers show slightly higher rates of cognitive and motor impairments, potentially linked to:

• • Greater fetal growth restriction.

  • Increased exposure to prenatal complications.

  • Higher rates of cesarean delivery can impact gut microbiome and immune development.

Social and Healthcare Disparities Across Maternal Age Groups

Beyond biology, maternal age is a proxy for complex social determinants of health. Adolescents often face barriers related to:

• Incomplete education.

• Limited financial resources.

• Unstable housing.

• Lower access to specialized perinatal care.

Older mothers, particularly those with infertility histories, often have:

• More frequent contact with high-risk obstetric care.

• Higher adherence to prenatal screening.

• Greater financial resources and health literacy.

These differences shape the quality of prenatal care, access to neonatal intensive care units (NICUs), and long-term follow-up services — all of which directly influence VLBW outcomes.

Implications for Clinical Care

Tailoring perinatal care strategies to maternal age can optimize outcomes for VLBW infants:

• For Adolescent Mothers:

  • Enhanced prenatal education and outreach.

  • Focused nutritional support.

  • Programs to improve early postpartum follow-up and parenting skills.

• For Advanced Maternal Age Mothers:

  • Close monitoring for hypertensive disorders and placental dysfunction.

  • Targeted fetal surveillance programs.

  • Personalized counseling on delivery timing and neonatal risks.

Conclusion

Maternal age has a significant impact on the course of VLBW singleton infants. Adolescents and older maternal-age mothers have unique biological, obstetric, and social issues, all of which influence neonatal survival, morbidity, and long-term outcomes. Awareness of these age-specific differences enables clinicians to tailor prenatal, perinatal, and postnatal care, ultimately enhancing outcomes for this high-risk group.

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