The relationship of neurodevelopmental impairment to concurrent early childhood outcomes of extremely preterm infants

Infant Mortality Categorized by Birth Weight Percentiles for Deliveries between 22 and 28 Weeks of Gestation

OBJECTIVE

 Our objective was to describe infant mortality within 1 year of life according to gestational age and birth weight percentile in infants delivered between 22 and 28 weeks of gestation.

STUDY DESIGN

 This study was a retrospective cohort study based on publicly available U.S. birth certificate data linked to infant death data between 2014 and 2020. Maternal-neonate pairs of singleton live births between 220/7 and 286/7 weeks' gestation (vaginal or cesarean) were evaluated. We excluded infants with major fetal anomalies, chromosomal disorders, and birth weight outliers. Our primary outcome was infant mortality within 1 year of life. Individuals were categorized into eight sex-specific birth weight percentiles categories: less than the 3rd, 3rd-less than the 10th, 10th-less than the 25th, 25th-to less than the 50th, 50th-less than the 75th, 75th-to less than the 90th, 90th-less than the 97th, and 97th or higher.

RESULTS

 Of 27,014,444 individuals with live births from January 2014 to December 2020, 151,677 individuals who gave birth at 22 to 28 weeks of gestation were included in the study population. The mortality rate ranged from 4.2% for the 50th-less than the 75th percentiles at 28 weeks to 80.3% for the 3rd-less than the 10th percentile at 22 weeks. Using the 50th-less than the 75th birth weight percentile at each gestational age as a reference group, birth weight less than the 50th percentile was associated with increased mortality at all gestational ages in a dose-dependent manner. From 22 to 25 weeks of gestation, higher birth weight percentiles were associated with lower mortality, while the 97th or higher birth weight percentile was associated with increased mortality compared with the 50th-less than the 75th birth weight percentile at 26 to 28 weeks of gestation.

CONCLUSION

 The lower birth weight percentiles were associated with higher mortality across all gestational ages, but the association between higher birth weight percentiles and infant mortality exhibited an opposite pattern at 22 to 25 weeks as compared to later gestational age.

KEY POINTS

· Birth weight ≥97th percentile was associated with increased infant mortality at 26 to 28 weeks.. · Higher birth weight percentiles were associated with a lower risk of mortality at 22 to 25 weeks.. · Lower birth weight percentiles were associated with a higher risk of mortality at 22 to 28 weeks..

Associations between feeding and development in preterm infants in the NICU and throughout the first year of life

BACKGROUND

There is little published evidence regarding associations between feeding and development in preterm infants which could help identify infants most needing follow-up services.

AIMS

To determine if preterm infant feeding and development were predictable throughout the first year of life and identify associations with maternal factors, neonatal factors, and socioeconomic measures.

STUDY DESIGN

Prospective single-site study of the feeding and development of extremely and very preterm infants at three time points throughout the first year of life.

SUBJECTS

Infants <32 weeks gestational age were followed from neonatal intensive care unit (NICU) discharge (DC) until 12 months corrected gestational age (CGA).

OUTCOME MEASURES

Feeding and development were evaluated at NICU DC, 3 months and 12 months CGA. Maternal health, infant health, and socioeconomic measures were also recorded.

RESULTS

Significant differences were found between assessments for feeding and development at each of the three time points: NICU DC (p = 0.026), 3 months CGA (p = 0.001), and 12 months CGA (p = 0.000); however, no associations were found between feeding and development at NICU DC and 12 months CGA (p = 0.137). Of the maternal factors determined to be significant, none were consistent enough as to be considered relevant.

CONCLUSIONS

This study demonstrated that preterm infants with typical feeding and development at DC may go on to develop concerns in these areas, and those who scored abnormally at DC may perform typically during the first year of life. This study affirms the importance of NICU follow-up services to support feeding and development for all infants born <32 weeks gestation.

Perinatal management: Lessons learned from the neonatal research network

Recent contributions of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network (NRN) regarding obstetrical perinatal interventions and neonatal delivery room practices include the following: the impact of multiple antepartum factors including maternal diabetes, hypertension, obesity and mode of delivery on outcomes of extremely preterm newborns, effects of delayed delivery interval for extremely preterm multiples, effects of antenatal steroids on preterm newborn outcomes and the impact of antenatal magnesium sulfate therapy on neurodevelopmental outcomes for extremely preterm infants. NRN studies also contribute important evidence for neonatal delivery room resuscitation guidelines including umbilical cord management and maintenance of euthermia immediately after birth. The updated NRN outcome calculator helps better counsel families regarding possible outcomes for the most immature newborns if resuscitation is attempted at birth. Thus, the NRN provides substantial information regarding effects of perinatal management on newborn infants.

Early neurodevelopmental follow-up in the NICHD neonatal research network: Advancing neonatal care and outcomes, opportunities for the future

At the inception of the Eunice Kennedy Shriver National Institute of Child Health and Development Neonatal Research Network (NRN), provision of care for extremely preterm (EPT) infants was considered experimental. The NRN Follow-up Study Group, initiated in 1993, developed infrastructure with certification processes and standards, allowing the NRN to assess 2-year outcomes for EPT and to provide important metrics for randomized clinical trials. This chapter will review the NRN Follow-up Study Group's contributions to understanding factors related to improved neurodevelopmental, behavioral, and social-emotional outcomes of EPT infants. We will also discuss follow up challenges, including reassessing which outcomes are most meaningful for parents and investigators. Finally, we will explore how outcome studies have informed clinical decisions and ethical considerations, given limitations of prediction of complex later childhood outcomes from early neurodevelopmental findings.

Two-year neurodevelopmental outcome in children born extremely preterm: the EPI-DAF study

OBJECTIVE

In 2010, the Dutch practice regarding initiation of active treatment in extremely preterm infants was lowered from 25 completed weeks' to 24 completed weeks' gestation. The nationwide Extremely Preterm Infants - Dutch Analysis on Follow-up Study was set up to provide up-to-date data on neurodevelopmental outcome at 2 years' corrected age (CA) after this guideline change. Design: National cohort study.

PATIENTS

All live born infants between 24^0/7 weeks' and 26^6/7 weeks' gestational age who were 2 years' CA in 2018-2020.

MAIN OUTCOME MEASURE

Impairment at 2 years' CA, based on cognitive score (Bayley-III-NL), neurological examination and neurosensory function.

RESULTS

651 of 991 live born infants (66%) survived to 2 years' CA, with data available for 554 (85%). Overall, 62% had no impairment, 29% mild impairment and 9% moderate-to-severe impairment (further defined as neurodevelopmental impairment, NDI). The percentage of survivors with NDI was comparable for infants born at 24 weeks', 25 weeks' and 26 weeks' gestation. After multivariable analysis, severe brain injury and low maternal education were associated with higher odds on NDI. NDI-free survival was 48%, 67% and 75% in neonatal intensive care unit (NICU)-admitted infants at 24, 25 and 26 weeks' gestation, respectively.

CONCLUSIONS

Lowering the threshold has not been accompanied by a large increase in moderate-to-severely impaired infants. Among live-born and NICU-admitted infants, an increase in NDI-free survival was observed from 24 weeks' to 26 weeks' gestation. This description of a national cohort with high follow-up rates gives an accurate description of the range of outcomes that may occur after extremely preterm birth.

Neurodevelopmental Outcomes of Infants at <29 Weeks of Gestation Born in Canada Between 2009 and 2016

OBJECTIVE

To evaluate changes in mortality or significant neurodevelopmental impairment (NDI) in children born at <29 weeks of gestation in association with national quality improvement initiatives.

STUDY DESIGN

This longitudinal cohort study included children born at 22^0/7 to 28^6/7 weeks of gestation who were admitted to Canadian neonatal intensive care units between 2009 and 2016. The primary outcome was a composite rate of death or significant NDI (Bayley Scales of Infant and Toddler Development, Third Edition score <70, severe cerebral palsy, blindness, or deafness requiring amplification) at 18-24 months corrected age. To evaluate temporal changes, outcomes were compared between epoch 1 (2009-2012) and epoch 2 (2013-2016). aORs were calculated for differences between the 2 epochs accounting for differences in patient characteristics.

RESULTS

The 4426 children included 1895 (43%) born in epoch 1 and 2531 (57%) born in epoch 2. Compared with epoch 1, in epoch 2 more mothers received magnesium sulfate (56% vs 28%), antibiotics (69% vs 65%), and delayed cord clamping (37% vs 31%) and fewer infants had a Score for Neonatal Acute Physiology, version II >20 (31% vs 35%) and late-onset sepsis (23% vs 27%). Death or significant NDI occurred in 30% of children in epoch 2 versus 32% of children in epoch 1 (aOR, 0.86; 95% CI, 0.75-0.99). In epoch 2, there were reductions in the need for hearing aids or cochlear implants (1.4% vs 2.6%; aOR, 0.50; 95% CI, 0.31-0.82) and in blindness (0.6% vs.1.4%; aOR, 0.38; 95% CI, 0.18-0.80).

CONCLUSIONS

Among preterm infants born at <29 weeks of gestation, composite rates of death or significant NDI and rates of visual and hearing impairment were significantly lower in 2013-2016 compared with 2009-2012.

Longitudinal medical needs for periviable NICU survivors

OBJECTIVE

To evaluate the technologies required, medications needed, and early intervention services utilized from discharge to 12 months post-discharge for periviable infants (22 0/7 to 24 6/7 weeks gestational age) followed in a comprehensive NICU follow-up clinic.

STUDY DESIGN

Information regarding medication use, technology requirement, and early intervention services was collected prospectively at one, six, and twelve months after discharge. Neurodevelopmental assessment was completed at 12 months corrected age.

RESULT

69 periviable infants were actively treated and survived to discharge during the study period. 54 infants were enrolled and followed in the comprehensive NICU follow-up clinic. Use of technology and prescribed medications decreased with a 46% reduction of infants requiring ≥1 technology device (74.1% vs. 40.4%, p < 0.01) and 64% reduction in infants requiring ≥1 medication (88.9% vs 31.9%, p < 0.01) 12 months post discharge. There was an increase in early intervention services with 83% of infants receiving services by 12 months post discharge.

CONCLUSION

Technology and medication requirements were high at discharge but notably decreased in the first year after discharge concurrent with increased enrollment in early interventional services. Many periviable infants survive without severe short-term developmental delays.

Scaffolding Parenting and Health Development for Preterm Flourishing Across the Life Course

Advances in obstetrics and neonatal medicine have resulted in improved survival rates for preterm infants. Remarkably, >75% extremely (<28 weeks) preterm infants who leave the NICU do not experience major neurodevelopmental disabilities, although >50% experience more minor challenges in communication, perception, cognition, attention, regulatory, and executive function that can adversely impact educational and social function resulting in physical, behavioral, and social health issues in adulthood. Even late premature (32-36 weeks) infants have more neurodevelopmental challenges than term infants. Although early intervention and educational programs can mitigate risks of prematurity for children's developmental trajectories, restrictive eligibility requirement and limitations on frequency and intensity mean that many premature infants must "fail first" to trigger services. Social challenges, including lack of family resources, unsafe neighborhoods, structural racism, and parental substance use, may compound biological vulnerabilities, yet existing services are ill-equipped to respond. An intervention system for premature infants designed according to Life Course Health Development principles would instead focus on health optimization from the start; support emerging developmental capabilities such as self-regulation and formation of reciprocal secure early relationships; be tailored to each child's unique neurodevelopmental profile and social circumstances; and be vertically, horizontally, and longitudinally integrated across levels (individual, family, community), domains (health, education), and time. Recognizing the increased demands placed on parents, it would include parental mental health supports and provision of trauma-informed care. This developmental scaffolding would incorporate parenting, health, and developmental interventions, with the aim of improved health trajectories across the whole of the life course.

Mortality, In-Hospital Morbidity, Care Practices, and 2-Year Outcomes for Extremely Preterm Infants in the US, 2013-2018

IMPORTANCE

Despite improvement during recent decades, extremely preterm infants continue to contribute disproportionately to neonatal mortality and childhood morbidity.

OBJECTIVE

To review survival, in-hospital morbidities, care practices, and neurodevelopmental and functional outcomes at 22-26 months' corrected age for extremely preterm infants.

DESIGN, SETTING, AND PARTICIPANTS

Prospective registry for extremely preterm infants born at 19 US academic centers that are part of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Neonatal Research Network. The study included 10 877 infants born at 22-28 weeks' gestational age between January 1, 2013, and December 31, 2018, including 2566 infants born before 27 weeks between January 1, 2013, and December 31, 2016, who completed follow-up assessments at 22-26 months' corrected age. The last assessment was completed on August 13, 2019. Outcomes were compared with a similar cohort of infants born in 2008-2012 adjusting for gestational age.

EXPOSURES

Extremely preterm birth.

MAIN OUTCOMES AND MEASURES

Survival and 12 in-hospital morbidities were assessed, including necrotizing enterocolitis, infection, intracranial hemorrhage, retinopathy of prematurity, and bronchopulmonary dysplasia. Infants were assessed at 22-26 months' corrected age for 12 health and functional outcomes, including neurodevelopment, cerebral palsy, vision, hearing, rehospitalizations, and need for assistive devices.

RESULTS

The 10 877 infants were 49.0% female and 51.0% male; 78.3% (8495/10848) survived to discharge, an increase from 76.0% in 2008-2012 (adjusted difference, 2.0%; 95% CI, 1.0%-2.9%). Survival to discharge was 10.9% (60/549) for live-born infants at 22 weeks and 94.0% (2267/2412) at 28 weeks. Survival among actively treated infants was 30.0% (60/200) at 22 weeks and 55.8% (535/958) at 23 weeks. All in-hospital morbidities were more likely among infants born at earlier gestational ages. Overall, 8.9% (890/9956) of infants had necrotizing enterocolitis, 2.4% (238/9957) had early-onset infection, 19.9% (1911/9610) had late-onset infection, 14.3% (1386/9705) had severe intracranial hemorrhage, 12.8% (1099/8585) had severe retinopathy of prematurity, and 8.0% (666/8305) had severe bronchopulmonary dysplasia. Among 2930 surviving infants with gestational ages of 22-26 weeks eligible for follow-up, 2566 (87.6%) were examined. By 2-year follow-up, 8.4% (214/2555) of children had moderate to severe cerebral palsy, 1.5% (38/2555) had bilateral blindness, 2.5% (64/2527) required hearing aids or cochlear implants, 49.9% (1277/2561) had been rehospitalized, and 15.4% (393/2560) required mobility aids or other supportive devices. Among 2458 fully evaluated infants, 48.7% (1198/2458) had no or mild neurodevelopmental impairment at follow-up, 29.3% (709/2419) had moderate neurodevelopmental impairment, and 21.2% (512/2419) had severe neurodevelopmental impairment.

CONCLUSIONS AND RELEVANCE

Among extremely preterm infants born in 2013-2018 and treated at 19 US academic medical centers, 78.3% survived to discharge, a significantly higher rate than for infants born in 2008-2012. Among infants born at less than 27 weeks' gestational age, rehospitalization and neurodevelopmental impairment were common at 2 years of age.

Prenatal risk factors and neonatal DNA methylation in very preterm infants

Background

Prenatal risk factors are related to poor health and developmental outcomes for infants, potentially via epigenetic mechanisms. We tested associations between person-centered prenatal risk profiles, cumulative prenatal risk models, and epigenome-wide DNA methylation (DNAm) in very preterm neonates.

Methods

We studied 542 infants from a multi-center study of infants born < 30 weeks postmenstrual age. We assessed 24 prenatal risk factors via maternal report and medical record review. Latent class analysis was used to define prenatal risk profiles. DNAm was quantified from neonatal buccal cells using the Illumina MethylationEPIC Beadarray.

Results

We identified three latent profiles of women: a group with few risk factors (61%) and groups with elevated physical (26%) and psychological (13%) risk factors. Neonates born to women in higher risk subgroups had differential DNAm at 2 CpG sites. Higher cumulative prenatal risk was associated with methylation at 15 CpG sites, 12 of which were located in genes previously linked to physical and mental health and neurodevelopment.

Conclusion

We observed associations between prenatal risk factors and DNAm in very preterm infants using both person-centered and cumulative risk approaches. Epigenetics offers a potential biological indicator of prenatal risk exposure.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13148-021-01164-9.