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Sex differences in umbilical artery Doppler indices: a longitudinal study
Christian Widnes1,2, Kari Flo3,4, Tom Wilsgaard5
1Women's Health and Perinatology Research Group, Department of Clinical Medicine, Faculty of Health Sciences, UiT-The Arctic University of Norway, Tromso, Norway. Christian.Widnes@unn.no.
Biology of Sex Differences
|April 20, 2018
Summary
Fetal sex influences umbilical artery Doppler indices and heart rate in the second half of pregnancy. New sex-specific reference ranges are established for improved diagnostics and monitoring.
Area of Science:
- Perinatal medicine
- Fetal ultrasonography
- Reproductive physiology
Background:
- Sexual dimorphism in placental function is recognized, but its impact on umbilical artery (UA) waveforms is debated.
- Previous studies suggest sex differences in UA pulsatility index (PI), necessitating further investigation.
- Establishing sex-specific reference ranges for UA Doppler indices may enhance clinical diagnostics.
Purpose of the Study:
- To investigate gestational age-associated changes in UA Doppler indices during the second half of pregnancy.
- To compare UA Doppler indices between male and female fetuses.
- To establish sex-specific reference ranges for UA Doppler indices and fetal heart rate (HR).
Main Methods:
- Prospective longitudinal study involving 294 low-risk singleton pregnancies (19-40 weeks gestation).
- Serial measurements of UA Doppler indices (PI, RI, S/D) and fetal HR obtained every 4 weeks.
- Sex-specific reference intervals calculated using multilevel modeling.
Main Results:
- UA Doppler indices and fetal HR were significantly associated with gestational age and HR.
- Female fetuses exhibited 2-8% higher UA Doppler indices than male fetuses from 20-36 weeks gestation.
- Female fetuses showed higher HR from 26 weeks gestation until term.
Conclusions:
- Gestational age-dependent sex differences in UA Doppler indices and fetal HR were identified.
- New sex-specific reference ranges for UA Doppler indices and fetal HR were established.
- These ranges can refine diagnostics and improve monitoring of individual pregnancies.
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