Anthropometric measurements in the second trimester fetus

Area of Science:

• Fetal medicine and dysmorphology
• Quantitative anthropometry and biometry

Background:

• Lack of established normal anthropometric data for second-trimester fetuses hinders the objective assessment of subtle dysmorphic features.
• Existing measurements are primarily for neonates, leaving a gap in early fetal developmental assessment.

Purpose of the Study:

• To establish normal anthropometric measurements for fetuses between 13 and 26 weeks gestation.
• To derive growth ratios for objective assessment of dysmorphic features.
• To provide clinicians and pathologists with tools for early and accurate diagnosis.

Main Methods:

• Recorded 19 anthropometric measurements at autopsy on 260 normal singleton fetuses (13-26 weeks gestation).
• Derived regression lines and growth ratios for each parameter.
• Compared derived measurements with established ultrasound reference ranges.

Main Results:

• Established linear correlations between gestational age and growth parameters (r > 0.90 for most).
• Derived growth parameter ratios demonstrated higher correlations than individual parameters, suggesting reduced error from gestational age estimation.
• Biparietal diameter and head circumference showed concordance with ultrasound ranges; abdominal circumference was lower.

Conclusions:

• The study provides objective anthropometric data and ratios crucial for dysmorphologists assessing second-trimester fetuses.
• Derived ratios aid in objectively evaluating head shape, limb-trunk proportions, and major body segment relationships.
• These tools can rapidly confirm clinical impressions and enhance diagnostic accuracy in fetal assessment.