Table 2. Duration of expulsive efforts (EE) among cases and controls.

Duration of EE (minutes)	Controls N = 762	PPH N = 3852	p**	Severe PPH N = 1048	p**
Median [interquartiles]	18[10–27]	20 [14–30]	<0.01	23 [14–32]	<0.01
Percentiles among controls (n (%) *
≤18 minutes	313 (50.9)	1307 (39.1)		316 (35.1)
]18–27]	155 (25.2)	875 (26.2)		244 (27.1)
]27–37]	88 (14.3)	654 (19.6)		185 (20.6)
>37	59 (9.6)	508 (13.2)		155 (17.2)
Missing	147 (19.3)	508 (13.2)	<0.01	148 (14.1)	<0.01

* For the missing data, percentages are calculated for the entire group. For the other categories, percentages are calculated in excluding the missing data

** Chi2 and Wilcoxon tests not taking missing data into account