Long-Term Outcomes of Moderately Preterm, Late Preterm, and Early Term Infants

Key points

Background

The National Institute of Child Health and Human Development panel reviewed the evidence of increased risk of infants with a gestation age of 34 to 36 weeks and changed the earlier definition of “near term” to “LPT” in 2006.¹ Currently, MPT infants born at 32 to 33 weeks' gestation and LPT infants born at 34 to 36 weeks' gestation make up the largest subgroup of preterm (PT) infants and contribute to more than 80% of premature births in the United States. There are increasing numbers of reports

Maternal factors

Mothers of PT infants are more likely to have their own medical morbidities including high blood pressure, diabetes, and obesity.⁴ Some subgroups of parent-infant dyads may have greater vulnerability. Brandon and colleagues⁵ reported that mothers of LPT infants have greater emotional distress (anxiety, postpartum depression, posttraumatic stress symptoms, and worry about their infant) after delivery than mothers of FT infants. In addition, their distress remained higher than that of FT mothers

Neonatal characteristics

The increased neonatal and postdischarge vulnerability of MPT and particularly LPT infants has been underestimated in the past. Their level of maturation is compromised compared to an FT infant, placing them at increased risk of a spectrum of clinical medical problems including hypothermia, respiratory disorders, hypoglycemia, jaundice, immunologic problems, and increased susceptibility to infection as well as feeding problems.⁸ LPT infants are also at increased risk of admission to an NICU,

Postdischarge medical problems

After discharge from the hospital, LPT infants continue to have increased medical needs and are 2 to 3 times more likely to be rehospitalized or visit an emergency room than FT infants.14, 15 In an outcome study of 26,703 infants followed up for the first 6 months of life, rehospitalization rates between 15 and 182 days after discharge were inversely related to the GA and ranged from 3.6% for infants born at or after 41 weeks; 4.4%, for 38 to 40 weeks; 5.6%, for 37 weeks; 7.3%, for 36 weeks;

Neurodevelopmental outcome studies

Outcome studies of both MPT and LPT infants indicate that they are at increased risk of developmental disability, school failure, behavior problems, social and medical disabilities, and death.18, 19, 20, 21, 22, 23 There are, however, a limited number of neurodevelopmental studies of MPT and LPT infants, because in the past, they have been considered low risk both as neonates and postdischarge. Most NICUs have follow-up programs for very PT infants who are considered at greatest risk of

Early term infants

ET gestation is defined as deliveries occurring at 37 to 38 weeks of gestation. Although FT deliveries have traditionally been defined as births after 36 weeks, the FT category has been further divided to include ET (37–38 weeks), term (39–41 weeks), and late term or postterm (42–44 weeks). The focus of recent reports has been on the increased vulnerability of ET infants. A report on US births between 1992 and 2002 indicated an 8.9% increase in ET births over a 10-year period, with the increase

Summary

There is increasing evidence that MPT infants are at increased risk of a spectrum of developmental and behavioral morbidities that extend from birth to adult age. There is also an increasing body of evidence of the vulnerability of the LPT infant, particularly those who require NICU care, for postdischarge sequelae. The data on increased risk of behavioral and psychiatric morbidities for both MPT and LPT infants are of particular concern. Current evidence indicates that close surveillance of