Table 2.

Sample size calculation for unmatched case-control study by open Epi software [18]

No	Variables	Proportion of controls with exposure	Proportion of cases with exposure	95 %CI OR	Sample size	Ref
1.	Meconium stained liquor	25.1 %	40.13 %	2(1.2–2.9)	Cases: 122	[19]
					Control: 243
					Total: 365
2.	Operative delivery	45.7 %	62.73 %	2(1.02–3.11)	Cases: 109	[20]
					Control: 218
					Total:327
3.	Induction/augmentation	59.3 %	87.6 %	4.85(1.71,13)	Cases:34	[11]
					Control:68 Total:102