Factors associated with readmission in late-preterm infants: a matched case-control study

Objective: The goal of this study was to evaluate risk factors for readmission among late-preterm (34-36 weeks' gestation) infants in clinical practice.

Methods: This was a retrospective, matched case-control study of late-preterm infants receiving care across 8 regional hospitals in 2009 in the United States. Those readmitted within 28 days of birth were matched to non-readmitted infants at a ratio of 1:3 according to birth hospital, birth month, and gestational age. Step-wise modeling with likelihood ratio tests were used to develop a multivariable logistic regression model. A subgroup analysis of hyperbilirubinemia readmissions was also performed.

Results: Of 1861 late-preterm infants delivered during the study period, 67 (3.6%) were readmitted within 28 days of birth. These were matched to 201 control infants, for a final sample of 268 infants. In multivariable regression, each additional day in length of stay was associated with a significantly reduced odds ratio (OR) for readmission (0.57, P = .004); however, for those infants delivered vaginally, there was no significant association between length of stay and readmission (adjusted OR: 1.08, P = .16). A stronger inverse relationship was observed in subgroup analysis for hyperbilirubinemia readmissions, with the adjusted OR associated with increased length of stay 0.40 (P = .002) for infants born by cesarean delivery but 1.14 (P = .27) for those delivered vaginally.

Conclusions: Infants born via cesarean delivery with longer length of hospital stay have a decreased risk for readmission. As hospitals implement protocols to standardize length of stay, mode of delivery may be a useful factor to identify late-preterm infants at higher risk for readmission.