1. Report of Iranian fetuses’s CRL at GA between 11W+0D to 13W+6D
Dr. Sarang Younesi
Nilou Medical Laboratory
Tehran, Iran October/2014

2. Optimal position for measuring NT
1. The magnification should be as large as possible and always such that each slight movement of the callipers produces only a 0.1 mm change in the measurement
2. CRL Between mm
3. A mid sagittal section and fetal head and upper thorax should be included in the image.
4. The fetus should be in a neutral position, with the head in line with the spine.
- Hyperextended (0.6 mm increase)
- Flexed (0.4 mm decrease)

3. Design
A retrospective study of Iranian pregnant women who referred to the Nilou Laboratory for doing FTS from the beginning of 2007 to the end of October % Of women were from Tehran and its suburbs.

4. No. Sonographer (FMF Certified)
Design
No. Sonographer (FMF Certified) 5

5. Design
Crown-rump length may be used to accurately date pregnancy between 7 and 13 weeks' gestation.
The technique involves measurement of the fetal length from the tip of the cephalic pole to the tip of the caudal pole.
The fetus should be at rest and assuming its natural curvature.

6. CRL

7. Determination of Gestational Age by CRL
Crown Rump Length:
Gestational age = 6 weeks plus (CRL x days). This relies on the growth of the normal fetus of 1 mm per day after the 6th week of gestation.
For example, a CRL of 16 mm would correspond to a gestational age of 8 weeks and two days (6 weeks plus 16 days = 8 weeks and 2 days).

8. Design Average GA Based CRL, BPD, FL, HC, AC Correlation between
CRL Average GA

9. Comparative Table between GA & CRL (54,307 Fetuses)
GA (W+D)
Mean (Iran)
CRL (mm)
in Iran
Mean (Ref.)
in Fef.
11+0 40
39.0 – 41.0 46
45.0 – 47.0
11+1 42
41.1 – 43.0 48
47.1 – 49.0 ’’
13+5 78
77.1 – 79.0
81.7
81.1 – 82.5
13+6 80
79.1 – 81.0
83.3
82.6 – 84.0

10. Causes 1- Vit D3 Deficiency (Sunlight …) 2- Consumption of Dairy
3- Creams with SPF ↑

11. Ultrasound Markers
CRL = mm
In IRAN: mm

12. Criteria CRL Instead of
Recommended
Criteria CRL Instead of ↓
Gestational Age