Background
Umbilical cord arterial and venous blood gas values reflect the acid-base balance
status of a newborn at birth. Derangement in these values has been linked to poor
neonatal outcomes in term and late preterm neonates; however, the utility of these
values in preterm neonates of <29 weeks’ gestation is unclear.
Objective
This study aimed to determine the associations of umbilical cord arterial and venous
blood gas values with neonatal mortality and severe neurologic injury in extremely
preterm neonates and to identify the cutoff values associated with 2.5-fold increases
or decreases in the posttest probabilities of outcomes.
Study Design
This was a retrospective cohort study of neonates who were born at 23+0 to 28+6 weeks’
gestation between January 1, 2018 and December 31, 2019, and who were admitted to
neonatal units in Canada.
Exposure
Various cut-offs of umbilical cord blood gas values and lactate values were studied.
Main Outcomes and Measures
The main outcomes were mortality before discharge from the neonatal unit and severe
neurologic injury defined as grade 3 or 4 periventricular or intraventricular hemorrhage
or periventricular leukomalacia. The outcome rates were calculated for various cutoff
values of umbilical cord blood gas parameters and were adjusted for birthweight, gestational
age, sex, and multiple births. Likelihood ratios were calculated to derive posttest
probabilities.
Results
A total of 1040 and 1217 neonates had analyzable umbilical cord arterial and venous
blood gas values, respectively. In the cohort, the mean (standard deviation) gestational
age was 26.5 (1.5) weeks, the mean birthweight was 936 (215) g, the prevalence of
mortality was 10% (105/1040), and the prevalence of severe neurologic injury was 9%
(92/1016). An umbilical cord arterial pH of ≤7.1 and base excess of ≤−12 mmol/L were
associated with >2.5-fold higher posttest probability of mortality, and an umbilical
cord arterial or venous lactate value of <3 was associated with a 2.5-fold lower posttest
probability of mortality. An umbilical cord arterial lactate value of <3 was associated
with a lower posttest probability of severe neurological injury.
Conclusion
In preterm neonates of <29 weeks’ gestation, low umbilical cord arterial pH and high
umbilical cord arterial base excess values were associated with a clinically important
increase in the posttest probability of mortality, whereas low umbilical cord arterial
or venous lactate values were associated with a decrease in the posttest probability
of mortality.
Key words
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Article Info
Publication History
Published online: January 05, 2022
Accepted:
January 4,
2022
Received in revised form:
December 23,
2021
Received:
August 5,
2021
Footnotes
The authors report no conflict of interest.
Although no specific funding was received for this study, organizational support for the Canadian Neonatal Network and the Canadian Preterm Birth Network (CPTBN) was provided by the Maternal-Infant Care Research Centre (MiCare) at Mount Sinai Hospital in Toronto, Ontario, Canada. MiCare is supported by the Canadian Institutes of Health Research (CIHR) (CTP 87518) and Mount Sinai Hospital. P.S.S. reports receiving funding from the CIHR for development of the CPTBN (PBN 150642). The funding sources had no role in the design or conduct of the study; the collection, management, analysis, or interpretation of the data; the preparation, review, or approval of the manuscript; or the decision to submit the manuscript for publication.
Individual deidentified patient data from the study reported in this article, will not be publicly available.
Cite this article as: Shah PS, Barrett J, Claveau M, et al. Association of umbilical cord blood gas values with mortality and severe neurologic injury in preterm neonates <29 weeks’ gestation: a national cohort study. Am J Obstet Gynecol 2022;227:85.e1-10.
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