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Systematic review and meta-analysis of birth weight and perfluorohexane sulfonate exposures: examination of sample timing and study confidence
  1. Hongyu Ru1,
  2. Alexandra L Lee1,
  3. Kristen M Rappazzo2,
  4. Michael Dzierlenga1,
  5. Elizabeth Radke3,
  6. Thomas F Bateson3,
  7. J Michael Wright4
  1. 1 Office of Research and Development, Center for Public Health and Environmental Assessment; Chemical and Pollutant Assessment Division, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
  2. 2 Office of Research and Development, Center for Public Health and Environmental Assessment; Public Health and Environmental Systems Division, US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
  3. 3 Office of Research and Development, Center for Public Health and Environmental Assessment; Chemical and Pollutant Assessment Division, US Environmental Protection Agency, Washington, District of Columbia, USA
  4. 4 Office of Research and Development, Center for Public Health and Environmental Assessment; Chemical and Pollutant Assessment Division, US Environmental Protection Agency, Cincinnati, Ohio, USA
  1. Correspondence to Dr J Michael Wright, Office of Research and Development, Center for Public Health and Environmental Assessment; Chemical and Pollutant Assessment Division, US Environmental Protection Agency, Cincinnati, Ohio, USA; wright.michael{at}epa.gov

Abstract

We examined the association between mean birth weight (BW) differences and perfluorohexane sulfonate (PFHxS) exposure biomarkers.

We fit a random effects model to estimate the overall pooled effect and for different strata based on biomarker sample timing and overall study confidence. We also conducted an analysis to examine the impact of a continuous measure of gestational age sample timing on the overall pooled effect.

We detected a −7.9 g (95% CI −15.0 to –0.7; pQ=0.85; I2=0%) BW decrease per ln ng/mL PFHxS increase based on 27 studies. The 11 medium confidence studies (β=−10.0 g; 95% CI −21.1 to 1.1) showed larger deficits than 12 high (β=−6.8 g; 95% CI −16.3 to 2.8) and 4 low confidence studies (β=−1.5 g; 95% CI −51.6 to 48.7). 10 studies with mid-pregnancy to late-pregnancy sampling periods showed smaller deficits (β=−3.9 g; 95% CI −17.7 to 9.9) than 5 post-partum studies (β=−28.3 g; 95% CI −69.3 to 12.7) and 12 early sampling studies (β=−7.6 g; 95% CI −16.2 to 1.1). 6 of 12 studies with the earliest sampling timing showed results closer to the null.

Overall, we detected a small but statistically significant BW deficit across 27 studies. We saw comparable BW deficit magnitudes in both the medium and high confidence studies as well as the early pregnancy group. Despite no definitive pattern by sample timing, larger deficits were seen in postpartum studies. We also saw results closer to the null for a subset of studies restricted to the earliest biomarker collection times. Serial pregnancy sampling, improved precision in gestational age estimates and more standardised reporting of sample variation and exposure units in future epidemiologic research may offer a greater understanding of the relationship between PFHxS on BW and any potential impact of pregnancy haemodynamics.

  • Meta-analysis
  • Epidemiology
  • Environment

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Footnotes

  • Contributors The authors confirm contribution to the paper as follows: study conception and design: JMW; data collection: HR and JMW; analysis and interpretation of results: HR, ALL, KMR, MD, ER, TFB and JMW; draft manuscript preparation: HR and JMW. All authors reviewed the results and approved the final version of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Disclaimer The views expressed in this article are those of the author(s) and do not necessarily represent the views or policies of the US Environmental Protection Agency.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.