Gestational age reference from crown-rump length during 11-14 weeks: a population-based multicenter cohort study in...

Area of Science:

• Obstetrics and Gynecology
• Medical Imaging
• Fetal Medicine

Background:

• Accurate gestational age (GA) estimation is crucial for optimal pregnancy management.
• Existing ultrasonographic dating formulas may have population-specific limitations.
• Developing a refined formula for the Chinese population is warranted.

Purpose of the Study:

• To develop and validate a new ultrasonographic formula for estimating GA based on fetal crown-rump length (CRL).
• To assess the accuracy of the new formula in a Chinese population.
• To compare its performance against established dating formulas.

Main Methods:

• A prospective, multicenter study involving 4,710 healthy, low-risk singleton pregnancies in China.
• Ultrasonography performed between 11-14 weeks of gestation.
• Development of a regression model using a development cohort (70%) and validation in a separate cohort (30%).

Main Results:

• A linear relationship was observed between CRL and GA (11-14 weeks), yielding the equation GA = 59.590085 + 0.458539 × CRL (R² = 0.8042).
• The new formula demonstrated a mean difference of 0.32 days between estimated GA and menstrual age.
• This error was significantly smaller compared to five established CRL-based dating formulas.

Conclusions:

• A novel CRL-based dating formula was successfully derived for naturally conceived pregnancies at 11-14 weeks gestation.
• The new formula provides a more accurate estimation of GA with minimal residuals.
• This offers a valuable and improved tool for obstetric dating in the target population.