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Amniotic fluid volume in normal singleton pregnancies: modeling with quantile regression.

Adam T Sandlin1, Songthip T Ounpraseuth, Horace J Spencer

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This study establishes reliable reference ranges for amniotic fluid volume (AFV) in normal pregnancies using quantile regression. The findings provide accurate AFV charts across gestation for better clinical assessment.

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Area of Science:

  • Perinatal medicine
  • Biostatistics
  • Obstetrics

Background:

  • Accurate assessment of amniotic fluid volume (AFV) is crucial for monitoring fetal well-being.
  • Existing reference ranges may not adequately capture the variability of AFV across gestation.
  • Quantile regression (QR) offers a flexible statistical approach for establishing normative data.

Purpose of the Study:

  • To develop uniform and reliable reference ranges for amniotic fluid volume (AFV) across gestation.
  • To utilize quantile regression (QR) for establishing normative AFV centiles in normal singleton pregnancies.
  • To provide improved clinical tools for assessing AFV during pregnancy.

Main Methods:

  • Analysis of true AFVs from 379 normal singleton pregnancies (16-41 weeks gestation).
  • Determination of AFV using dye-dilution or direct measurement at cesarean delivery.
  • Application of quantile regression (QR) to establish AFV centiles and model AFV-gestational age relationships.

Main Results:

  • Quantile regression successfully established normative centile charts for true AFVs.
  • A nonlinear relationship between AFV and gestational age was identified at the upper centile range (≥80th percentile).
  • The study provides a more accurate representation of AFV distribution across gestation.

Conclusions:

  • Normative centile charts for true AFVs in normal singleton pregnancies (16-41 weeks) have been defined using QR.
  • Quantile regression provides a more appropriate statistical method for reflecting true AFV across gestation at various centiles compared to standard linear regression.
  • These charts enhance the ability to assess AFV at specific centiles, aiding clinical decision-making.