Gestational dating by metabolic profile at birth: a California cohort study

Persistent Pulmonary Hypertension of the Newborn in Late Preterm and Term Infants in California

BACKGROUND AND OBJECTIVES

There are limited epidemiologic data on persistent pulmonary hypertension of the newborn (PPHN). We sought to describe the incidence and 1-year mortality of PPHN by its underlying cause, and to identify risk factors for PPHN in a contemporary population-based dataset.

METHODS

The California Office of Statewide Health Planning and Development maintains a database linking maternal and infant hospital discharges, readmissions, and birth and death certificates from 1 year before to 1 year after birth. We searched the database (2007-2011) for cases of PPHN (identified by International Classification of Diseases, Ninth Revision codes), including infants ≥34 weeks' gestational age without congenital heart disease. Multivariate Poisson regression was used to identify risk factors associated with PPHN; results are presented as risk ratios, 95% confidence intervals.

RESULTS

Incidence of PPHN was 0.18% (3277 cases/1 781 156 live births). Infection was the most common cause (30.0%). One-year mortality was 7.6%; infants with congenital anomalies of the respiratory tract had the highest mortality (32.0%). Risk factors independently associated with PPHN included gestational age <37 weeks, black race, large and small for gestational age, maternal preexisting and gestational diabetes, obesity, and advanced age. Female sex, Hispanic ethnicity, and multiple gestation were protective against PPHN.

CONCLUSIONS

This risk factor profile will aid clinicians identifying infants at increased risk for PPHN, as they are at greater risk for rapid clinical deterioration.

Postnatal Prediction of Gestational Age Using Newborn Fetal Hemoglobin Levels

Introduction

In many parts of the developing world procurement of antenatal gestational age estimates is not possible, challenging provision of appropriate perinatal care. This study aimed to develop a model for postnatal gestational age estimation utilizing measures of the newborn hemoglobin levels and other metabolic analyte data derived from newborn blood spot samples.

Methods

We conducted a retrospective cohort analysis of 159,215 infants born January 2012–December 2014 in Ontario, Canada. Multivariable linear and logistic regression analyses were used to evaluate the precision of developed models.

Results

Models derived from a combination of hemoglobin ratios and birthweight were more precise at predicting gestational age (RMSE1·23 weeks) than models limited to birthweight (RMSE1·34). Models including birthweight, hemoglobin, TSH and 17-OHP levels were able to accurately estimate gestational age to ± 2 weeks in 95·3% of the cohort and discriminate ≤ 34 versus > 34 (c-statistic, 0·98). This model also performed well in small for gestational age infants (c-statistic, 0·998).

Discussion

The development of a point-of-care mechanism to allow widespread implementation of postnatal gestational age prediction tools that make use of hemoglobin or non-mass spectromietry-derived metabolites could serve areas where antenatal gestational age dating is not routinely available.

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Mechanisms for postnatal gestational age estimation are required to guide care in low resource settings.

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Newborn fetal/adult hemoglobin ratio and other non-mass spectrometry derived data can be used to provide precise estimates of gestational age.

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Hemoglobin derived postnatal gestational age prediction models also performed comparatively well in small for gestational age infants.

Three research groups including our own have recently published on the development of postnatal gestational age prediction algorithms derived from newborn screening metabolic profiles. Expanded newborn screening practices relying on tandem mass spectrometry instrumentation are not common place in many low resource settings, thus limiting the utility of such prediction models. Newborn fetal and adult hemoglobin levels are known to vary by gestational age of birth, and may be derived by methods other than mass spectrometry. In this study we used a retrospective cohort study design to develop and validate the precision of postnatal gestational age prediction models derived from fetal and adult hemoglobin levels, and readily available perinatal characteristics obtained from the Better Outcomes Registry & Network and the Newborn Screening of Ontario program. Final models were able to accurately predict postnatal gestational age to within 2 weeks of true gestational age, with excellent precision to discriminate the gestational age of average and small for gestational age infants. We have built upon our existing postnatal gestational age prediction algorithm to demonstrate both the stand-alone and additive predictive potential of newborn hemoglobin levels to the model. Methods to predict gestational age based on newborn screening markers have the potential to provide accurate postnatal assessments of gestational age in settings where gold standard first trimester ultrasounds are limited.