Table 3.

Cervical length among the study participants

Cervical length (cm)	Total (n = 70)	Incidence of preterm birth		Test of significance	P
		Yes (n = 22)	No (n = 48)
1st visit
Mean ± SD	3.75 ± 0.51	3.60 ± 0.60	3.81 ± 0.45	t = 1.681	0.097 (NS)
2nd visit
Mean ± SD	3.26 ± 0.44	3.0 ± 0.49	3.38 ± 0.36	t = 3.715*	< 0.001* (S)
3rd visit	(n = 52)	(n = 4)	(n = 48)
Mean ± SD	3.01 ± 0.33	2.94 ± 0.42	3.02 ± 0.33	t = 0.452	0.653 (NS)

SD Standard deviation, t Student t-test, p p value, *: statistically significant at p ≤ 0.05

1^st visit: 16 ^0/7 weeks – 24 ^0/7 weeks

2^nd visit: 24 ^1/7 weeks – 32 ^0/7 weeks

3^rd visit: 32 ^1/7 weeks – 36 ^6/7 weeks