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  • Original Article
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Population-based reference curve for umbilical cord arterial pH in infants born at 28 to 42 weeks

Journal of Perinatology volume 37, pages 254–259 (2017)Cite this article

Subjects

Abstract

Objective:

The objective of the study was to examine normal variations of umbilical cord arterial pH by gestational age (GA).

Study Design:

Population-based cohort study of 46 199 infants born from 2008 to 2014 in Stockholm, Sweden, with GA 28 to 42 weeks, Apgar score ⩾7 at 5 min, non-instrumental vaginal delivery, and birth weight for GA⩾3rd and ⩽97th percentile. Quantile regression was used to investigate the associations between GA and infant sex, and pH.

Results:

The mean umbilical cord arterial pH (s.d.) was 7.29 (0.10), 7.27 (0.07), 7.25 (0.07) and 7.23 (0.07) among infants born at 28 to 31, 32 to 36, 37 to 41 and 42 weeks, respectively. Arterial pH decreased linearly with increasing GA, and female infants had higher pH than male infants (P<0.001).

Conclusion:

Umbilical cord arterial pH varied in a linear fashion by GA and was influenced by infant sex. The provided reference curve taking GA into account may yield a more accurate definition of acidosis at birth.

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Acknowledgements

Professor Sven Cnattingius initiated and conceptualized the research database, and is responsible for the database infrastructure. The work was supported by the Stockholm County Council (ALF 20130156, 20140105, 20150118 and post-doctoral financial support); and the Swedish Research Council (2013–2429). The funders had no involvement in study design, collection, analysis, and/or interpretation of data, writing of the report or the decision to submit the paper for publication.

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Authors and Affiliations

  1. Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden

    B Skiöld

  2. Department of Neonatology, Karolinska University Hospital, Stockholm, Sweden

    B Skiöld

  3. Department of Medicine Solna, Clinical Epidemiology Unit, Karolinska Institutet, Stockholm, Sweden

    G Petersson, M Ahlberg, O Stephansson & S Johansson

  4. School of Public Health, University of California, Berkeley, CA, USA

    O Stephansson

  5. Department of Clinical Science and Education, Karolinska Institutet, Stockholm, Sweden

    S Johansson

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  1. B Skiöld
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  2. G Petersson
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Corresponding author

Correspondence to S Johansson.

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Supplementary Information accompanies the paper on the Journal of Perinatology website

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Skiöld, B., Petersson, G., Ahlberg, M. et al. Population-based reference curve for umbilical cord arterial pH in infants born at 28 to 42 weeks. J Perinatol 37, 254–259 (2017). https://doi.org/10.1038/jp.2016.207

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