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¹ This chapter does not include references. Citations to support the text and conclusions herein are provided in previous chapters of the report.

increases from 22 to 28 weeks because the survival rate increases. However, disability among survivors decreases throughout this gestational age range, and survival without disability increases from 23 percent at 22 weeks to 71 percent at 27 weeks.

Although all preterm and LBW neonates have increased rates of short- and long-term morbidity, morbidity is inversely proportional to gestational age. For example, approximately 7 percent of children worldwide who are born prior to 37 weeks gestation will experience some moderate to severe delay in the form of neurodevelopmental impairment. The highest risk for morbidity and mortality is among infants born at less than 32 weeks gestation and less than 1500 grams. The risk of impairment among children born preterm increases with birth at earlier gestational ages, with an estimated 24 percent of children born prior to 31 weeks and up to 52 percent of those born prior to 28 weeks showing impairment. Cognitive, motor, behavioral, and functional/school outcomes improve as gestational age increases.

1. There is an inverse relationship between gestational age and mortality and health outcomes among infants born preterm, as well as health outcomes among infants born small for gestational age.
   • Survivability has increased among preterm newborns over the past two decades. However, increased survivability at earlier gestational ages results in increased short- and long-term morbidities and functional limitations that may require lifelong intervention.
   • Among infants born preterm, the risk of long-term impairments and secondary health conditions that adversely affect functioning is more strongly associated with gestational age than with birth weight.
   • Children born preterm or LBW may experience a wide range of health conditions, including motor disorders (e.g., cerebral palsy, developmental coordination disorder), sensory disorders (e.g., vision loss, hearing loss), cognitive disorders (e.g., attention-deficit/hyperactivity disorder, intellectual developmental disorder), social-emotional behavioral disorders (e.g., anxiety, depression), and communication disorders (e.g., autism spectrum disorder).
   • With continued improvement in neonatal care, more children will survive at younger gestational ages, and the population of those with morbidities will increase.

Developmental Trajectories

Development refers to an active process that depends on the codevelopment of various physiological and organ systems with experiences and the environment in the context of genetic and epigenetic factors.

Neurodevelopment is an active process that depends on the formation of neural networks in the nervous system, which in turn depends on a developing child’s physical and psychosocial environments, beginning in utero and continuing after birth. Developmental skills provide the scaffolding for function. When a child has a health condition or impairment that impedes skill development, it negatively affects function. Assuming a typical developmental trajectory, a child’s attainment of skills within the first years of life is rapid and expansive and continues at least into early adulthood. Although there is seldom a one-to-one correspondence between developmental and functional domains, skills in all developmental domains will impact those in all functional domains, especially over time. Disruption of development because of LBW or preterm birth can result in persistent altered developmental trajectories that will impact the degree of functioning and independence attained in adulthood. Development can be disrupted by genetic, medical, environmental, and psychosocial factors, including those identified as social determinants of health.

2. Normal development is an active process that depends on the appropriate formation of neural networks and the integrity of physiological systems, as well as a developing child’s physical and psychosocial environments, beginning in utero and continuing after birth.
   • Development occurs across multiple domains (i.e., motor, cognition, communication, social-emotional, adaptive).
   • Anything that interferes with an environment (internal or external) conducive to optimal development can negatively affect a child’s development, potentially resulting in functional limitations or ongoing health conditions.
   • Increasing medical and psychosocial risk factors may have an additive effect on development and function, resulting in increased complexity in the care and intervention needed.
   • Infants who are preterm often require intensive and/or extended hospitalization, which significantly limits their ability to function normally in a family unit, impeding normal development and altering growth trajectories.
   • Social determinants of health are among the environmental factors that can affect children’s development positively (opportunities) or negatively (barriers).

Function and Outcomes

Preterm or LBW status at birth confers significant risk for medical morbidities, social-emotional dysfunction, and various cognitive impairments. Affected children will have variable outcomes in these areas related

to gestational age and birth weight. Typically, those born at earlier gestational ages (e.g., <32 weeks) and lower birth weights (<1500 grams) are more likely to experience persistent and severe health problems and functional limitations relative to those born at later gestational ages and higher birth weights. Health conditions and impairments associated with preterm birth or LBW can affect every body system and have chronic, lifelong impacts on health, function, and well-being. Although not all children born LBW will have significant medical comorbidities, increased survivability at early gestational ages has resulted in a new cohort of children with significant complications of varying severity. In addition, many children born preterm experience multiple medical comorbidities, with a clear additive effect on functional outcomes.

3. Children born preterm or LBW have increased risk for associated impairments and health conditions that can have negative sequelae affecting all body systems, with lifelong impacts across all functional domains.
   • All functional domains identified in the Social Security Administration’s (SSA’s) disability determination process for children may be affected by the impairments and health conditions associated with preterm birth and LBW.
   • The occurrence of multiple medical comorbidities has a negative additive effect on functional outcomes.
   • Some developmental problems associated with LBW, particularly those involving higher-order, or advanced, cognitive skills, may not be identified until a later age, when those skills are typically expected to appear.
   • Social determinants of health, including socioeconomic status, structural racism, and access to resources, directly influence all outcomes across all medical and neurodevelopmental domains.

Treatments and Services

Health care providers use developmental milestones in developmental surveillance and screening of infants and children, especially during well-child visits, to identify those who have delays or other atypical development. Children’s skills in all domains, as well as overall functioning, require close monitoring and prompt therapeutic intervention when delays or atypicalities are detected. Developmental outcomes can be improved by early screening and identification, which can lead to early implementation of effective interventions. Evidence increasingly shows that growth, health, and development are impacted by a wide range of medical, educational, and psychosocial determinants.

In the past two decades, advances in neonatal care, such as routine use of antenatal steroids and reduction in postnatal steroid use, increased

use of noninvasive respiratory support, and sepsis prevention initiatives, have focused on improving outcomes for children born preterm while maintaining or improving survival. Complementing advances in medical care, hospital-based modifications to environments and specific developmental interventions have been implemented in some neonatal intensive care units (NICUs) to promote optimal neonatal development. Examples of such interventions include implementation of kangaroo care, minimized handling of extremely LBW infants by medical staff, reduced direct lighting, and increased involvement of parents in the day-to-day care of their infants.

The services and treatments currently available for LBW children are heavily influenced by the life-course model of care, which emphasizes that interventions have different impacts over time depending on the point in a child’s development at which they are provided: In general, the earlier and more sustained a service is, the greater is its long-term impact on the growth and development of LBW infants. Although research has not always been focused on effectiveness in relation to the age at which therapy starts, interventions provided during the emergence of skills earlier in life rather than those aimed at modifying already learned behavior later in life can be expected to lead to better outcomes.

4. Appropriate and timely screenings, evaluations, treatments, and services are expected to improve outcomes among children born LBW. There is general consensus that the earlier and more sustained a developmental or educational intervention is, the greater will be its long-term impact on growth, development, and functioning for LBW infants.
   • The foundation of development and the acquisition of developmental and functional skills is an active interplay between physiological and anatomical maturation and environmental experience, including parental and family interaction.
   • In the past two decades, medical and nonmedical advances in neonatal care have focused on improving outcomes for children born preterm while maintaining or improving survival.
   • Guidelines and systems for identifying children in need of intervention have evolved over the past 20 years to include the expectation of routine universal developmental surveillance and screening, referral, and interventions for developmental delays and health conditions, such as hearing loss.
   • Barriers to accessing screenings, evaluations, and interventions (e.g., living in underresourced areas, insufficient numbers and distribution of professionals, fragmentation of services, lack of coordination across service sectors) significantly impact outcomes for children born preterm or LBW.

ameliorate the negative effects of social determinants of health and improve outcomes for these infants across all domains.

• The prevalence of preterm birth and LBW, as well as rates of survival and health and developmental outcomes for these infants, may be negatively affected by social determinants of health, including but not limited to unstable and inadequate housing, food insecurity, unsafe neighborhoods, and structural racism.
• Targeted policy interventions, such as cash and food transfers, expanded access to health insurance, and paid family leave, can enhance child and family resiliency and improve outcomes.

SSA’s Disability Criteria and Low Birth Weight

Supplemental Security Income (SSI) has been shown to improve outcomes for child recipients and their families. However, evidence for positive effects specific to infants eligible for SSI based on the LBW criteria is limited and mixed, indicating the need for additional research. The birth weight cutoffs specified by SSA in the listing criteria (i.e., less than 1200 grams at birth or the birth weights relative to gestational age [see Table 1-1 in Chapter 1]) differ from the current standard criteria used by the medical community. Notably, the 1200 gram criterion for SSI falls between the medical criteria for extremely LBW (<1000 grams) and very LBW (<1500 grams). Among children who are developing at the appropriate weight for gestational age, girls reach 1200 grams between 31 and 32 weeks gestation, while boys do so between 30 and 31 weeks. Birth during this timeframe is considered very preterm. Among children who are large for gestational age, birth weight does not drop below 1200 grams until 27 weeks gestation for girls and 26 weeks for boys. Birth during this timeframe is considered extremely preterm.

Similarly, the listing criteria for birth weight relative to gestational age do not correspond to the percentile cutoffs (3rd or 10th) used by the medical community to identify neonates who are considered small for gestational age. Accordingly, based solely on its LBW listing criteria, SSA would consider only 16 percent of infants defined as LBW by the medical community (i.e., <2500 grams) eligible for SSI benefits. Based on raw birth certificate data for 2021, about 50 percent of infants born very LBW as defined by the medical community (i.e., 1000 to <1500 grams) would not have met the current SSA LBW listing criteria even if they met the financial criteria for eligibility.

6. The current criteria in the LBW listing in SSA’s Listing of Impairments do not consistently correspond to the current and standard medical

definitions of LBW, preterm birth, or small for gestational age (SGA) neonates. Criteria based on birth weight do not take into account that gestational age is a better predictor of short- and long-term outcomes among infants born preterm.

• Among preterm infants, gestational age is a better predictor than birth weight of both short- and long-term outcomes.
• A birth weight of less than 1500 grams is considered very LBW and is close to the 50th percentile for weight at 32 weeks gestation. A birth weight of 1500 grams better corresponds to a gestational age of 32 weeks, after which the risk of severe impairments decreases.
• Infants born SGA (i.e., below the 10th percentile for gestational age) are at increased risk of having medical morbidities and developmental delays associated with poor growth of the brain and body. SGA is an important category of LBW infants born after 32 weeks gestation because their physiology and outcomes are comparable to those of appropriate weight infants who are born earlier.
• Persistent medical and neurodevelopmental conditions associated with LBW can provide alternative diagnoses or listings by which infants allowed disability benefits under the LBW listing may continue to qualify for benefits following a Continuing Disability Review.

SELECTED FINDINGS AND CONCLUSIONS IN SUPPORT OF OVERALL CONCLUSIONS

Box 6-1 shows the links between the overall conclusions presented above and some of the most relevant chapter-specific findings and conclusions that support them.²

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² Not all of the committee’s chapter-specific findings and conclusions are included in Box 6-1. Those that are included are numbered according to the chapter in which they appear.