Maternal Age, Multiple Birth, and Extremely Low Birth Weight Infants

Objectives

To compare the rates of adverse neurodevelopmental outcome or death at 18 to 22 months among extremely low birth weight (ELBW) infants born to mothers ≥40 years to the corresponding rates among infants of younger mothers.

Study design

Prospective evaluation of ELBW infants to quantify the relative risks of maternal age and multiple birth for death or adverse neurodevelopmental outcome.

Results

The sample consisted of 14 671 live ELBW births divided into maternal age groups: <20, 20 to 29, 30 to 39, and ≥40 years. Of infants born to mothers ≥40 years, 20% were multiples. Mothers ≥40 years had high rates of obstetric interventions and medical morbidities compared with mothers <40 years. ELBW live births of mothers ≥40 years were 22% more likely to survive and had a 13% decreased risk of neurodevelopmental impairment or death compared with mothers <20. Multiple birth, however, was associated with a 10% greater risk of neurodevelopmental impairment or death.

Conclusion

Although mothers ≥40 years had high pregnancy-related morbidities, we found no overall increased risk of the composite outcome of death or NDI. Multiple birth, however, was a predictor of all adverse outcomes examined, regardless of maternal age.

Abbreviations: ART, Assisted reproductive technology, CP, Cerebral palsy, ELBW, Extremely-low-birth-weight, NDI, Neurodevelopmental impairment, MDI, Bayley II mental developmental index, PDI, Psychomotor developmental index, PPROM, Preterm premature rupture of membranes