Am J Perinatol 2021; 38(S 01): e155-e161
DOI: 10.1055/s-0040-1708800
Original Article

Mild Neonatal Acidemia is Associated with Neonatal Morbidity at Term

1  Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Washington University in St. Louis School of Medicine, St. Louis, Missouri
,
1  Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Washington University in St. Louis School of Medicine, St. Louis, Missouri
,
1  Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Washington University in St. Louis School of Medicine, St. Louis, Missouri
,
Nandini Raghuraman
1  Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Washington University in St. Louis School of Medicine, St. Louis, Missouri
,
George A. Macones
2  Department of Women's Health, The University of Texas at Austin, Dell Medical School, Austin, Texas
,
Alison G. Cahill
2  Department of Women's Health, The University of Texas at Austin, Dell Medical School, Austin, Texas
› Author Affiliations
Funding This study received funding from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (R01HD061619-01; A.G.C., principal investigator). A.G.C. was a Robert Wood Johnson Foundation Faculty Physician Scholar, which partially supported this work.

Abstract

Objective The aim of this study is to determine the association between mild acidemia (umbilical artery [UA] pH: 7.11–7.19) and neonatal morbidity in neonates at term.

Study Design This is a secondary analysis of a prospective cohort of women admitted for labor at ≥37 weeks of gestation within a single institution from 2010 to 2015. Universal umbilical cord blood gas assessment was performed and validated. A composite neonatal morbidity index was created including respiratory distress, mechanical ventilation, meconium aspiration syndrome, suspected or confirmed sepsis, hypoxic-ischemic encephalopathy, need for therapeutic hypothermia, seizures and death. The cohort was stratified by UA pH into normal (≥7.20), mild acidemia (7.11–7.19), acidemia (7.00–7.10), and severe acidemia (≤7.00). A subanalysis was also performed where neonates with UA pH between 7.11 and 7.19 were further stratified into two groups (7.11–7.14 and 7.15–7.19) to determine if mildly acidotic infants at the lower end of the pH range were at increased risk of morbidity. Multivariable logistic regression was used to estimate the association between UA pH and neonatal morbidity.

Results Among 6,341 participants, 614 (9.7%) had mild acidemia. These infants were more likely to experience morbidity compared with those with normal UA pH (adjusted odds ratio [aOR]: 2.14; [1.68–2.73]). Among neonates with mild acidemia, UA pH 7.11 to 7.14 was associated with increased risk of composite neonatal morbidity (aOR: 3.02; [1.89–4.82]), as well as respiratory distress and suspected or confirmed sepsis when compared with UA pH 7.15 to 7.19.

Conclusion These data demonstrate that term neonates with mild acidemia at birth are at higher odds for short-term morbidity compared with neonates with normal UA pH. Furthermore, among neonates with mild acidemia, those with lower UA pH had worse neonatal outcomes than those with higher UA pH. This suggests that closer evaluation of neonates with UA pH higher than traditionally used could allow for earlier detection of morbidity and possible intervention.

Key Points

  • Neonates with mild acidemia (umbilical artery [UA] pH: 7.11–7.19) demonstrated an increased risk of composite morbidity compared with those with normal UA pH (≥7.20).

  • Among neonates with mild acidemia, those with lower UA pH (7.11–7.14) had a greater risk of morbidity compared with those with higher UA pH (7.15–7.19), suggesting a progression of risk of morbidity as UA pH decreases.

  • The majority of prior research has focused on severe acidemia (UA pH ≤ 7.00) using outcomes of severe neurologic morbidity and mortality. These data suggest that an increased risk of morbidity exists at higher pH values when more proximal and less severe outcomes are included, such as respiratory distress and neonatal sepsis.

Note

This study was presented at the Society for Maternal–Fetal Medicine's Annual Meeting, February 13 to 16, 2019, Las Vegas, NV.

The contents of this publication are solely the responsibility of the authors and do not necessarily represent the official view of the National Institutes of Health or the Robert Wood Johnson Foundation.




Publication History

Received: 11 December 2019

Accepted: 13 February 2020

Publication Date:
22 April 2020 (online)

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