Infants Born at Late Preterm Gestation: Management during the Birth Hospitalization.

OBJECTIVE: To examine the admission practices, frequency of common clinical morbidities, and rates of medical intervention in infants born at 34-36 weeks gestational age (GA, late preterm). STUDY DESIGN: This retrospective, single institution, cohort study analyzed electronic health records of infants born late preterm from 2019 through 2021. Infants with known congenital anomalies necessitating neonatal intensive care unit admission were excluded. Analysis included descriptive and inferential statistics. RESULTS: The study included 1022 infants: 209 (21%) 34 weeks GA, 263 (26%) 35 weeks GA, and 550 (54%) 36 weeks GA. Sixty-three percent of infants at 35 weeks GA and 78% of infants of 36 weeks GA remained in well newborn care throughout the birth hospitalization; infants born at 34 weeks GA were ineligible for well newborn care. The need for respiratory support was 32%, 18%, and 11% in infants of 34, 35, and 36 weeks GA, respectively. Supplemental tube feeds were administered in 55%, 24%, and 8% of infants of 34, 35, and 36 weeks GA, respectively. Most infants born at 34 weeks GA (91%) were placed in an incubator; this was less frequent in infants at 35 (37%) and 36 weeks (16%). Tachypnea, hypoglycemia, and hypothermia were noted in 40%, 61%, and 57% of infants, respectively. A subset of these infants (30% with tachypnea, 23% with hypoglycemia, and 46% with hypothermia) required medical intervention for these abnormalities. CONCLUSIONS: This single-center study provides an outlook on the care of infants born late preterm. Multicenter studies can contextualize these findings in order to develop clinical benchmarks and quality markers for this large population of infants.

Readmission After Neonatal Intensive Care Unit Discharge: The Importance of Social Drivers of Health.

OBJECTIVE: To determine associations between sociodemographic and medical factors and odds of readmission after discharge from the neonatal intensive care unit for infants with very low birth weight (<1500g). STUDY DESIGN: Cohort study using linked data from the California Perinatal Quality Care Collaborative, California Vital Statistics, and the Child Opportunity Index (COI) 2.0. Infants with very low birth weight born from 2009 through 2018 in California were considered. Odds ratios of readmission within 30 days of discharge adjusting for infant medical factors, maternal sociodemographic factors, and birth hospital were calculated via multivariable logistic regression and fixed-effect logistic regression models. RESULTS: A total of 42 411 infants met inclusion criteria. Also, 8.5% of all infants were readmitted within 30 days of discharge. In addition to traditional medical risk factors, two sociodemographic factors were significantly associated with increased odds of readmission in adjusted models: payor other than private insurance for delivery [aOR = 1.25 (95% CI 1.14-1.36)] and maternal education of less than high school degree [aOR = 1.19 (95% CI 1.06-1.33)]. Neighborhood Child Opportunity Index was not associated with odds of readmission. CONCLUSIONS: Sociodemographic factors, including lack of private insurance and lower maternal educational attainment, are significantly and independently associated with increased odds of readmission after neonatal intensive care unit discharge, in addition to traditional medical risk factors. Socioeconomic deprivation and health literacy may contribute to risk of readmission. Targeted discharge interventions focused on addressing social drivers of health warrant exploration.

Racial and Ethnic Inequities in Therapeutic Hypothermia and Neonatal Hypoxic-Ischemic Encephalopathy: A Retrospective Cohort Study.

OBJECTIVE: To investigate racial inequities in the use of therapeutic hypothermia (TH) and outcomes in infants with hypoxic-ischemic encephalopathy (HIE). STUDY DESIGN: We queried an administrative birth cohort of mother-baby pairs in California from 2010 through 2019 using International Classification of Diseases codes to evaluate the association between race and ethnicity and the application of TH in infants with HIE. We identified 4779 infants with HIE. Log-linear regression was used to calculate risk ratios (RR) for TH, adjusting for hospital transfer, rural location, gestational age between 35 and 37 weeks, and HIE severity. Risk of adverse infant outcome was calculated by race and ethnicity and stratified by TH. RESULTS: From our identified cohort, 1338 (28.0%) neonates underwent TH. White infants were used as the reference sample, and 410 (28.4%) received TH. Black infants were significantly less likely to receive TH with 74 (20.0%) with an adjusted risk ratio (aRR) of 0.7 (95% CI 0.5-0.9). Black infants with any HIE who did not receive TH were more likely to have a hospital readmission (aRR 1.36, 95% CI 1.10-1.68) and a tracheostomy (aRR 3.07, 95% CI 1.19-7.97). Black infants with moderate/severe HIE who did not receive TH were more likely to have cerebral palsy (aRR 2.72, 95% CI 1.07-6.91). CONCLUSIONS: In this study cohort, Black infants with HIE were significantly less likely to receive TH. Black infants also had significantly increased risk of some adverse outcomes of HIE. Possible reasons for this inequity include systemic barriers to care and systemic bias.

In Situ Simulation and Clinical Outcomes in Infants Born Preterm.

OBJECTIVE: To evaluate impact of a multihospital collaborative quality improvement project implementing in situ simulation training for neonatal resuscitation on clinical outcomes for infants born preterm. STUDY DESIGN: Twelve neonatal intensive care units were divided into 4 cohorts; each completed a 15-month long program in a stepped wedge manner. Data from California Perinatal Quality Care Collaborative were used to evaluate clinical outcomes. Infants with very low birth weight between 22 through 31 weeks gestation were included. Primary outcome was survival without chronic lung disease (CLD); secondary outcomes included intubation in the delivery room, delivery room continuous positive airway pressure, hypothermia (<36°C) upon neonatal intensive care unit admission, severe intraventricular hemorrhage, and mortality before hospital discharge. A mixed effects multivariable regression model was used to assess the intervention effect. RESULTS: Between March 2017 and December 2020, a total of 2626 eligible very low birth weight births occurred at 12 collaborative participating sites. Rate of survival without CLD at participating sites was 74.1% in March to August 2017 and 76.0% in July to December 2020 (risk ratio 1.03; [0.94-1.12]); no significant improvement occurred during the study period for both participating and nonparticipating sites. The effect of in situ simulation on all secondary outcomes was stable. CONCLUSIONS: Implementation of a multihospital collaborative providing in situ training for neonatal resuscitation did not result in significant improvement in survival without CLD. Ongoing in situ simulations may have an impact on unit practice and unmeasured outcomes.

Current Trends in Invasive Closure of Patent Ductus Arteriosus in Very Low Birth Weight Infants in United States Children's Hospitals, 2016-2021.

OBJECTIVE: To describe the current practices in invasive patent ductus arteriosus (PDA) closure (surgical ligation or transcatheter occlusion) in very low birth weight (VLBW) infants and changes in patient characteristics and outcomes from 2016 to 2021 among US children's hospitals. STUDY DESIGN: We evaluated a retrospective cohort of VLBW infants (birth weight 400-1499 g and gestational age 22-31 weeks) who had invasive PDA closure within 6 months of age from 2016 to 2021 in children's hospitals in the Pediatric Health Information System. Changes in patient characteristics and outcomes over time were evaluated using generalized linear models and generalized linear mixed models. RESULTS: 2418 VLBW infants (1182 surgical ligation; 1236 transcatheter occlusion) from 42 hospitals were included. The proportion of infants receiving transcatheter occlusion increased from 17.2% in 2016 to 84.4% in 2021 (P < .001). In 2021, 28/42 (67%) hospitals had performed transcatheter occlusion in > 80% of their VLBW infants needing invasive PDA closure, compared with only 2/42 (5%) in 2016. Although median postmenstrual age (PMA) at PDA closure did not change for the overall cohort, PMA at transcatheter occlusion decreased from 38 weeks in 2016 to 31 weeks by 2020, P < .001. Among those infants not intubated prior to PDA closure, extubation within 3 days postprocedure increased over time (yearly adjusted odds ratios of 1.26 [1.08-1.48]). Length of stay and mortality did not change over time. CONCLUSION: We report rapid adoption of transcatheter occlusion for PDA among VLBW infants in US children's hospitals over time. Transcatheter occlusions were performed at younger PMA over time.

Association of Primary Language with Very Low Birth Weight Outcomes in Hispanic Infants in California.

OBJECTIVE: To determine the association of Spanish as a primary language for a family with the health outcomes of Hispanic infants with very low birth weight (VLBW, <1500g). STUDY DESIGN: Data from the California Perinatal Quality Care Collaborative (CPQCC) linked to hospital discharge records were analyzed. Hispanic infants with VLBW born between 2009 and 2018 with a primary language of English or Spanish were included. Outcomes selected were hypothesized to be sensitive to language barriers. Multivariable logistic regression models and mixed models estimated associations between language and outcomes. RESULTS: Of 18 364 infants meeting inclusion criteria, 27% (n = 4976) were born to families with Spanish as a primary language. In unadjusted analyses, compared with infants of primarily English-speaking families, these infants had higher odds of hospital readmission within 1 year (OR 1.11 [95% CI 1.02-1.21]), higher odds to receive human milk at discharge (OR 1.32 [95% CI 1.23-1.42]), and lower odds of discharge home with oxygen (OR 0.83 [95% CI 0.73-0.94]). In multivariable analyses, odds of readmission and home oxygen remained significant when adjusting for infant but not maternal and hospital characteristics. Higher odds for receipt of any human milk at discharge were significant in all models. Remaining outcomes did not differ between groups. CONCLUSIONS: Significant differences exist between Hispanic infants with VLBW of primarily Spanish-vs English-speaking families. Exploration of strategies to prevent readmissions of infants of families with Spanish as a primary language is warranted.

Active Treatment of Infants Born at 22-25 Weeks of Gestation in California, 2011-2018.

OBJECTIVE: To determine the rate and trend of active treatment in a population-based cohort of infants born at 22-25 weeks of gestation and to examine factors associated with active treatment. STUDY DESIGN: This observational study evaluated 8247 infants born at 22-25 weeks of gestation at hospitals in the California Perinatal Quality Care Collaborative between 2011 and 2018. Multivariable logistic regression was used to relate maternal demographic and prenatal factors, fetal characteristics, and hospital level of care to the primary outcome of active treatment. RESULTS: Active treatment was provided to 6657 infants. The rate at 22 weeks was 19.4% and increased with each advancing week, and was significantly higher for infants born between days 4 and 6 at 22 or 23 weeks of gestation compared with those born between days 0 and 3 (26.2% and 78.3%, respectively, vs 14.1% and 65.9%, respectively; P < .001). The rate of active treatment at 23 weeks increased from 2011 to 2018 (from 64.9% to 83.4%; P < .0001) but did not change significantly at 22 weeks. Factors associated with increased odds of active treatment included maternal Hispanic ethnicity and Black race, preterm premature rupture of membranes, obstetrical bleeding, antenatal steroids, and cesarean delivery. Factors associated with decreased odds included lower gestational age and small for gestational age birth weight. CONCLUSIONS: In California, active treatment rates at 23 weeks of gestation increased between 2011 and 2018, but rates at 22 weeks did not. At 22 and 23 weeks, rates increased during the latter part of the week. Several maternal and infant factors were associated with the likelihood of active treatment.

Qualitative evaluation of enabling factors and barriers to the success and sustainability of national public health institutes in Cambodia, Colombia, Liberia, Mozambique, Nigeria, Rwanda and Zambia.

OBJECTIVES: The success of National Public Health Institutes (NPHIs) in low-income and middle-income countries (LMICs) is critical to countries' ability to deliver public health services to their populations and effectively respond to public health emergencies. However, empirical data are limited on factors that promote or are barriers to the sustainability of NPHIs. This evaluation explored stakeholders' perceptions about enabling factors and barriers to the success and sustainability of NPHIs in seven countries where the U.S. Centers for Disease Control and Prevention (CDC) has supported NPHI development and strengthening. DESIGN: Qualitative study. SETTING: Cambodia, Colombia, Liberia, Mozambique, Nigeria, Rwanda and Zambia. PARTICIPANTS: NPHI staff, non-NPHI government staff, and non-governmental and international organisation staff. METHODS: We conducted semistructured, in-person interviews at a location chosen by the participants in the seven countries. We analysed data using a directed content analysis approach. RESULTS: We interviewed 43 NPHI staff, 29 non-NPHI government staff and 24 staff from non-governmental and international organisations. Participants identified five enabling factors critical to the success and sustainability of NPHIs: (1) strong leadership, (2) financial autonomy, (3) political commitment and country ownership, (4) strengthening capacity of NPHI staff and (5) forming strategic partnerships. Three themes emerged related to major barriers or threats to the sustainability of NPHIs: (1) reliance on partner funding to maintain key activities, (2) changes in NPHI leadership and (3) staff attrition and turnover. CONCLUSIONS: Our findings contribute to the scant literature on sustainability of NPHIs in LMICs by identifying essential components of sustainability and types of support needed from various stakeholders. Integrating these components into each step of NPHI development and ensuring sufficient support will be critical to strengthening public health systems and safeguarding their continuity. Our findings offer potential approaches for country leadership to direct efforts to strengthen and sustain NPHIs.

Evaluation of Trends in Bronchopulmonary Dysplasia and Respiratory Support Practice for Very Low Birth Weight Infants: A Population-Based Cohort Study.

OBJECTIVES: To characterize the incidence of bronchopulmonary dysplasia (BPD) over time and to test the association of multilevel factors, including respiratory support, with the diagnosis of BPD. STUDY DESIGN: This population-based cohort study included 40 268 infants born between 22 and 32 weeks of gestation at hospitals in California between 2008 and 2017. The diagnosis of BPD was based on respiratory support at 36 weeks postmenstrual age. Tests for linear trend and multivariable logistic regression analyses were performed. RESULTS: The rate of BPD was consistent year to year, and the mortality rate declined. The incidence of BPD was 23.5% for the overall cohort, 44.9% for infants born at <28 weeks of gestational age, and 45.2% for extremely low birth weight infants. For infants born at >26 weeks of gestational age, the incidence of BPD was significantly decreased in the most recent 3-year period compared with the earlier 3 years (OR, 0.91). Invasive ventilation during delivery room resuscitation (OR, 2.64) and after leaving the delivery room (OR, 10.02) conferred the highest risk of BPD compared with oxygen or no respiratory support. Noninvasive ventilation as maximum respiratory support at 36 weeks increased by 20% over time. CONCLUSIONS: Marked changes in noninvasive support care have occurred without an overall decline in BPD rate. Further research, quality improvement, and strategies, along with noninvasive respiratory support, are needed for a reduction in the incidence of BPD.

Population Improvement Bias Observed in Estimates of the Impact of Antenatal Steroids to Outcomes in Preterm Birth.

OBJECTIVE: To examine the hypothesis that increasing rates and differential uptake of antenatal steroids would bias estimation of impact of antenatal steroids on neonatal death and severe (grade III-IV) intraventricular hemorrhage (IVH). STUDY DESIGN: The study population included infants born between 24 and 28 weeks of gestational age in the California Perinatal Quality Care Collaborative. Outcomes were in-hospital mortality and severe IVH. Mixed multivariable logistic regression models estimated the effect of antenatal steroid exposure, one model accounting for individual risk factors as fixed effects, and a second model incorporating a predicted probability factor estimating overall risk status for each time period. RESULTS: The study cohort included 28 252 infants. Antenatal steroid exposure increased from 80.1% in 2005 to 90.3% in 2016, severe IVH decreased from 14.5% to 9.0%, and mortality decreased from 12.8% to 9.1%. When stratified by group, 3-year observed outcomes improved significantly in infants exposed to antenatal steroids (12.5%-8.6% for IVH, 11.5%-8.8% for death) but not in those not exposed (20.7%-19.1% and 16.6%-15.5%, respectively). Women not receiving antenatal steroids had greater risk profile (such as no prenatal care) and greater predicted probability for severe IVH and mortality. Both outcomes exhibited little change (P > .05) over time for the group without antenatal steroids. In contrast, in women receiving antenatal steroids, observed and adjusted rates for both outcomes decreased (P < .0001). CONCLUSIONS: As the population's proportion of antenatal steroid use increased, the observed positive effect of antenatal steroids also increased. This apparent increase may be designated as the "population improvement bias."

Treating Center Volume and Congenital Diaphragmatic Hernia Outcomes in California.

OBJECTIVE: To examined outcomes for infants born with congenital diaphragmatic hernias (CDH), according to specific treatment center volume indicators. STUDY DESIGN: A population-based retrospective cohort study was conducted involving neonatal intensive care units in California. Multivariable analysis was used to examine the outcomes of infants with CDH including mortality, total days on ventilation, and respiratory support at discharge. Significant covariables of interest included treatment center surgical and overall neonatal intensive care unit volumes. RESULTS: There were 728 infants in the overall CDH cohort, and 541 infants (74%) in the lower risk subcohort according to a severity-weighted congenital malformation score and never requiring extracorporeal membrane oxygenation. The overall cohort mortality was 28.3% (n = 206), and 19.8% (n = 107) for the subcohort. For the lower risk subcohort, the adjusted odds of mortality were significantly lower at treatment centers with higher CDH repair volume (OR, 0.41; 95% CI, 0.23-0.75; P = .003), ventilator days were significantly lower at centers with higher thoracic surgery volume (OR, 0.56; 9 5% CI, 0.33-0.95; P = .03), and respiratory support at discharge trended lower at centers with higher neonatal intensive care unit admission volumes (OR, 0.51; 9 5% CI, 0.26-1.02; P = .06). CONCLUSIONS: Overall and surgery-specific institutional experience significantly contribute to optimized outcomes for infants with CDH. These data and follow-on studies may help inform the ongoing debate over the optimal care setting and relevant quality indicators for newborn infants with major surgical anomalies.

Biliary Excretion Noted on Hepatobiliary Iminodiacetic Acid Scan Does Not Exclude Diagnosis of Biliary Atresia.

A hepatobiliary iminodiacetic acid (HIDA) scan is frequently used in an attempt to exclude biliary atresia in infants who are cholestatic. We present 6 cases of confirmed biliary atresia in infants who had biliary patency reported on HIDA scan. We demonstrate that misinterpreted HIDA scans led to delayed diagnosis and surgical intervention for biliary atresia.

Improved Referral of Very Low Birthweight Infants to High-Risk Infant Follow-Up in California.

OBJECTIVE: To examine changes in referral rates of very low birthweight (birthweight <1500 g) infants to high-risk infant follow-up in California and identify factors associated with referral before and after implementation of a statewide initiative in 2013 to address disparities in referral. STUDY DESIGN: We included very low birthweight infants born 2010-2016 in the population-based California Perinatal Quality Care Collaborative who survived to discharge home. We used multivariable logistic regression to examine factors associated with referral and derive risk-adjusted referral rates by neonatal intensive care unit (NICU) and region. RESULTS: Referral rate improved from 83.0% (preinitiative period) to 94.9% (postinitiative period); yielding an OR of 1.48 (95% CI, 1.26-1.72) for referral in the postinitiative period after adjustment for year. Referral rates improved the most (≥15%) for infants born at ≥33 weeks of gestation, with a birthweight of 1251-1500 g, and born in intermediate and lower volume NICUs. After the initiative, Hispanic ethnicity, small for gestational age status, congenital anomalies, and major morbidities were no longer associated with a decreased odds of referral. Lower birthweight, outborn status, and higher NICU volume were no longer associated with increased odds of referral. African American race was associated with lower odds of referral, and higher NICU level with a higher odds of referral during both time periods. Referral improved in many previously poor-performing NICUs and regions. CONCLUSIONS: High-risk infant follow-up referral of very low birthweight infants improved substantially across all sociodemographic, perinatal, and clinical variables after the statewide initiative, although disparities remain. Our results demonstrate the benefit of a targeted initiative in California, which may be applicable to other quality collaboratives.

Racial and Ethnic Disparities in Human Milk Intake at Neonatal Intensive Care Unit Discharge among Very Low Birth Weight Infants in California.

OBJECTIVES: To examine how infant and maternal factors, hospital factors, and neighborhood-level factors impact or modify racial/ethnic disparities in human milk intake at hospital discharge among very low birth weight infants. STUDY DESIGN: We studied 14 422 infants from 119 California Perinatal Quality Care Collaborative neonatal intensive care units born from 2008 to 2011. Maternal addresses were linked to 2010 census tract data, representing neighborhoods. We tested for associations with receiving no human milk at discharge, using multilevel cross-classified models. RESULTS: Compared with non-Hispanic whites, the adjusted odds of no human milk at discharge was higher among non-Hispanic blacks (aOR 1.33 [1.16-1.53]) and lower among Hispanics (aOR 0.83 [0.74-0.93]). Compared with infants of more educated white mothers, infants of less educated white, black, and Asian mothers had higher odds of no human milk at discharge, and infants of Hispanic mothers of all educational levels had similar odds as infants of more educated white mothers. Country of birth and neighborhood socioeconomic was also associated with disparities in human milk intake at discharge. CONCLUSIONS: Non-Hispanic blacks had the highest and Hispanic infants the lowest odds of no human milk at discharge. Maternal education and country of birth were the biggest drivers of disparities in human milk intake, suggesting the need for targeted approaches of breastfeeding support.

Home Oxygen Use for Preterm Infants with Bronchopulmonary Dysplasia in California.

OBJECTIVES: To identify predictors of home oxygen use in preterm infants with bronchopulmonary dysplasia (BPD) in a statewide cohort, identify hospital variation in home oxygen use, and determine the relationship between home oxygen use and neonatal intensive care unit discharge timing. STUDY DESIGN: This was a secondary analysis of California Perinatal Quality Care Collaborative data. Infants were born <32 weeks of gestation, diagnosed with BPD based on respiratory support at 36 weeks postmenstrual age (PMA), and discharged home. Risk factors for home oxygen use were identified using a logistic mixed model with center as random effect. Estimates were used to calculate each center's observed to expected ratio of home oxygen use, and a Spearman coefficient between center median PMA at discharge and observed and expected proportions of home oxygen use. RESULTS: Of 7846, 3672 infants (47%) with BPD were discharged with home oxygen. Higher odds of home oxygen use were seen with antenatal steroids, maternal hypertension, earlier gestational age, male sex, ductus arteriosus ligation, more ventilator days, nitric oxide, discharge from regional hospitals, and PMA at discharge (receiver operating characteristic area under the curve 0.85). Of 92 hospitals, home oxygen use ranged from 7% to 95%; 42% of observed home oxygen use was significantly higher or lower than expected given patient characteristics. The 67 community hospitals with higher observed rates of home oxygen had earlier median PMA at discharge (correlation -0.27, P = .024). CONCLUSIONS: Clinical and hospital factors predict home oxygen use. Home oxygen use varies across California, with community centers using more home oxygen having a shorter length of stay.

Factors Associated with Successful First High-Risk Infant Clinic Visit for Very Low Birth Weight Infants in California.

OBJECTIVES: To determine rates of at least 1 high-risk infant follow-up (HRIF) visit by 12 months corrected age, and factors associated with successful first visit among very low birth weight (VLBW) infants in a statewide population-based setting. STUDY DESIGN: We used the linked California Perinatal Quality of Care Collaborative and California Perinatal Quality of Care Collaborative-California Children's Services HRIF databases. Multivariable logistic regression examined independent associations of maternal, sociodemographic, neonatal clinical, and HRIF program factors with a successful first HRIF visit among VLBW infants born in 2010-2011. RESULTS: Among 6512 VLBW children referred to HRIF, 4938 (76%) attended a first visit. Higher odds for first HRIF visit attendance was associated with older maternal age (OR, 1.48; 95% CI, 1.27-1.72; 30-39 vs 20-29 years), lower birth weight (OR, 2.11; 95% CI, 1.69-2.65; ≤750 g vs 1251-1499 g), private insurance (OR, 1.65; 95% CI, 1.19-2.31), a history of severe intracranial hemorrhage (OR, 1.61; 95% CI, 1.12-2.30), 2 parents as primary caregivers (OR, 1.18, 95% CI 1.03-1.36), and higher HRIF program volume (OR, 2.62; 95% CI, 1.88-3.66; second vs lowest quartile); and lower odds with maternal race African American or black (OR, 0.65; 95% CI, 0.54-0.78), and greater distance to HRIF program (OR, 0.69; 95% CI, 0.57-0.83). Rates varied substantially across HRIF programs, which remained after risk adjustment. CONCLUSIONS: In a population-based California VLBW cohort, maternal, sociodemographic, and home- and program-level disparities were associated with HRIF non-attendance. These findings underscore the need to identify challenges in access and resource risk factors during hospitalization in the neonatal intensive care unit, provide enhanced education about the benefits of HRIF, and create comprehensive neonatal intensive care unit-to-home transition approaches.

Birth Hospitalization Costs and Days of Care for Mothers and Neonates in California, 2009-2011.

OBJECTIVE: To provide population-based estimates of the hospital-related costs of maternal and newborn care, and how these vary by gestational age and birth weight. STUDY DESIGN: We conducted a retrospective analysis of 2009-2011 California in-hospital deliveries at nonfederal hospitals with the infant and maternal discharge data successfully (96%) linked to birth certificates. Cost-to-charge ratios were used to estimate costs from charges. Physician hospital payments were estimated by mean diagnosis related group-specific reimbursement and costs were adjusted for inflation to December 2017 values. After exclusions for incomplete or missing data, the final sample was 1 265 212. RESULTS: The mean maternal costs for all in-hospital deliveries was $8204, increasing to $13 154 for late preterm (32-36 weeks) and $22 702 for very preterm (<32 weeks) mothers. The mean cost for all newborns was $6389: $2433 for term infants, $22 102 for late preterm, $223 931 for very preterm infants, and $317 982 for extremely preterm infants (<28 weeks). Preterm infants were 8.1% of cases but incurred 60.9% of costs; for very preterm and extremely preterm infants, these shares were 1.0% and 36.5%, and 0.4% and 20.0%, respectively. Overall, mothers incurred 56% of the total costs during the delivery hospitalization. CONCLUSIONS: Both maternal and neonatal costs are skewed, with this being much more pronounced for infants. Preterm birth is much more expensive than term delivery, with the additional costs predominately incurred by the infants. The small share of infants who require extensive stays in neonatal intensive care incur a large share of neonatal costs and these costs have increased over time.