Gender-Specific Antenatal Growth Reference Charts in Monochorionic Twins

Area of Science:

• Maternal-Fetal Medicine
• Prenatal Diagnostics
• Twin Gestation Studies

Background:

• Monochorionic (MC) twin pregnancies require specialized monitoring due to shared placental circulation.
• Accurate fetal growth assessment is crucial for timely intervention in MC twins.
• Existing growth charts may not adequately account for sex-specific growth patterns in MC twins.

Purpose of the Study:

• To develop antenatal, gender-specific reference growth charts for uncomplicated monochorionic diamniotic twins.
• To enhance the precision of prenatal assessment and surveillance in MC twin pregnancies.

Main Methods:

• Prospective longitudinal study of uncomplicated MC twin pregnancies from 23+4 weeks gestation.
• Bi-weekly ultrasound assessments of estimated fetal weight (EFW) and biometric parameters (biparietal diameter, head circumference, abdominal circumference, femur length).
• Multilevel mixed models used to fit charts for gestational age and fetal gender.

Main Results:

• Analysis included 456 ultrasound examinations from 62 MC twins.
• Gender-specific reference values (mean, 5th, and 95th percentiles) for EFW and biometry were established between 24 and 37 weeks gestation.
• Male fetuses demonstrated higher reference values than females, with greater disparity in upper centiles.

Conclusions:

• Gender-specific reference growth charts for MC twins have been created.
• These charts are expected to improve prenatal assessment and surveillance accuracy.
• Facilitates more precise classification of normal growth versus growth restriction, adjusted for fetal sex.