Table 2.

Descriptive statistics of ultrasound measurements (n = 1,692).

Ultrasound	Gestational age (weeks)	Fetal characteristics (mm)
		FL	HC	AC	BPD
First
No. of scans	—	512	512	498	553
Mean ± SD	12.2 ± 1.0	7.8 ± 2.5	75.3 ± 12.8	62.1 ± 11.5	20.7 ± 3.7
Second
No. of scans	—	560	556	560	561
Mean ± SD	21.1 ± 1.0	35.0 ± 3.3	189.1 ± 13.9	164.0 ± 14.2	49.5 ± 3.8
Third
No. of scans	—	555	554	554	553
Mean ± SD	34.0 ± 1.3	66.1 ± 3.2	309.2 ± 13.3	300.0 ± 16.2	86.1 ± 3.8
Fourth
No. of scans	—	17	17	17	17
Mean ± SD	35.1 ± 3.0	66.9 ± 6.5	318.3 ± 19.5	306.9 ± 28.8	86.7 ± 7.1
Fifth
No. of scans	—	2	2	2	2
Mean ± SD	33.7 ± 3.2	67.5 ± 10.6	331.5 ± 17.7	305.5 ± 20.5	85.5 ± 7.8
Sixth
No. of scans	—	1	1	0	1
Mean ± SD	34.4 ± 0	64.6 ± 0	342 ± 0	—	85.8 ± 0