Table 4. Summary of age-related correlation coefficients between different age groups.

Age group	Sex	Correlation coefficient
Fetal stage vs. 12 weeks	Male and Female	0.73±0.07
Fetal stage vs. 20 weeks	Male and Female	0.63±0.07
Fetal stage vs. 30 weeks	Male and Female	0.61±0.10
12 weeks vs. 20 weeks	Male and Female	0.89±0.06
12 weeks vs. 30 weeks	Male and Female	0.87±0.07
20 weeks vs. 30 weeks	Male and Female	0.95±0.02

Values are means±SD.