Reference Ranges of Amniotic Fluid Index in Late Third Trimester of Pregnancy: What Should the Optimal Interval between Two Ultrasound Examinations Be?

Table 3

Cohen coefficients of effect size at different intervals.

From	To
	35 weeks	36 weeks	37 weeks	38 weeks	39 weeks	40 weeks
34 weeks	0.21	0.85	1.29	1.38	1.86	2.18
35 weeks	#	0.7	1.16	1.27	1.77	2.12
36 weeks	#	#	0.46	0.6	1.11	1.42
37 weeks	#	#	#	0.17	0.69	0.98
38 weeks	#	#	#	#	0.49	0.76
39 weeks	#	#	#	#	#	0.24

0.2–0.49 small effect, 0.5–0.8 medium effect, and >0.8 large effect.
^#Comparison not done.