[Longitudinal reference intervals of maternal-fetal Doppler parameters]

Area of Science:

• Perinatal medicine
• Fetal imaging
• Doppler ultrasonography

Background:

• Doppler ultrasonography is crucial for assessing fetal well-being.
• Establishing accurate reference intervals for fetal Doppler parameters is essential for clinical interpretation.
• Existing reference intervals may not be universally applicable across diverse populations.

Purpose of the Study:

• To develop longitudinal reference intervals for pulsatility index (PI) in the umbilical artery (UA), middle cerebral artery (MCA), uterine artery (UtA), and ductus venosus (DV).
• To create these reference intervals specifically for a Brazilian pregnant population.
• To provide updated data for monitoring maternal-fetal hemodynamics.

Main Methods:

• A longitudinal observational study was conducted from February 2010 to May 2012.
• Low-risk pregnancies were scanned bi-weekly from 18 to 40 weeks of gestation.
• Linear mixed models were employed to generate 5th, 50th, and 95th percentile reference intervals for PI measurements.

Main Results:

• Longitudinal reference intervals for PI in UA, MCA, DV, and UtA were successfully established.
• Median PI values for UA, MCA, DV, and UtA showed significant decreases with advancing gestational age.
• Specific equations were derived for predicting median PI values based on gestational age for each vessel.

Conclusions:

• Longitudinal reference intervals for key gestational Doppler parameters were generated for a Brazilian cohort.
• These intervals may offer improved accuracy for tracking maternal-fetal hemodynamic changes in both normal and complicated pregnancies.
• Further validation is recommended to confirm the clinical utility of these new reference intervals.