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Reference range for cervical length in twin pregnancies
Mariza M Fujita1, Maria de Lourdes Brizot, Adolfo W Liao
1Department of Obstetrics, Hospital das Clinicas, São Paulo University Medical School, Rua Dr Enéas de Carvalho Aguiar, 225 São Paulo, SP, Brazil 05403-000.
Acta Obstetricia Et Gynecologica Scandinavica
|September 13, 2002
Summary
Cervical length measurement in twin pregnancies gradually shortens throughout gestation. This study establishes a reference range for cervical length, aiding in preterm birth risk assessment.
Area of Science:
- Maternal-Fetal Medicine
- Obstetrics
- Diagnostic Ultrasound
Background:
- Twin pregnancies face a higher risk of preterm delivery.
- Transvaginal ultrasound cervical length measurement is an effective screening tool for preterm birth.
- Establishing gestational age-specific reference ranges for cervical length in twin gestations is crucial.
Purpose of the Study:
- To establish a reference range for cervical length measurements throughout gestation in twin pregnancies.
- To provide data for improved preterm birth risk assessment in twin gestations.
Main Methods:
- Prospective study of 144 twin pregnancies delivering after 34 weeks.
- Transvaginal ultrasound measurement of cervical length every 4 weeks.
- Linear regression analysis to establish mean cervical length, 95% confidence intervals, and 95% prediction intervals throughout gestation.
Main Results:
- A significant inverse correlation was found between cervical length and gestational age (r=-0.43, p < 0.0001).
- Mean cervical length decreased by approximately 0.8 mm per week.
- Mean cervical length ranged from 47 mm at 13 weeks to 32 mm at 32 weeks, with lower 95% prediction limits of 29 mm and 15 mm, respectively.
Conclusions:
- Cervical length measurement demonstrates a gradual shortening throughout twin pregnancies.
- These findings provide essential reference data for monitoring cervical length in twin gestations.
- Understanding normal cervical length changes is vital for identifying pregnancies at risk of preterm delivery.