Risk Factors for Obstetric Anal Sphincter Injuries among Women Delivering at a Tertiary Hospital in Southwestern Uganda

Table 2

Baseline obstetric and clinical factors of study participants by case status.

Characteristic	Overall (N = 240)	Cases (N = 80)	Controls (N = 160)	value
	n/N (%)	n/N (%)	n/N (%)
Gravidity (N = 239)
Primigravida	94 (39.3)	50 (62.5)	44 (27.7)	<0.001
Multigravida	145 (60.7)	30 (37.5)	115 (72.3)
ANC attendance, yes (N = 239)	234 (97.9)	77 (97.5)	157 (98.1)	0.739
Gestational age at delivery (N = 239)				0.001
<37 wks.	6 (2.5)	1 (1.2)	5 (3.1)
37–42 wks.	192 (80.3)	75 (93.8)	117 (73.6)
>42 weeks	41 (17.15)	4 (5.0)	37 (23.3)
Time of delivery (N = 233)				0.967
Day time	150 (64.4)	51 (64.6)	99 (64.3)
Night time	83 (35.6)	28 (35.4)	55 (35.7)
Duration of 2nd stage of labour, minutes, median (IQR)	25 (10, 40)	30 (20, 53)	20 (10, 30)	0.001
Duration of 2nd stage of labour (N = 234)				<0.001
<1 hour	205 (87.6)	64 (76.2)	141 (94.0)
≥1 hour	29 (12.4)	20 (23.8)	9 (6.0)
Labour induction, yes (N = 229)	16 (7.0)	5 (6.7)	11 (7.1)	0.894
Labour augmentation, yes (N = 207)	19 (9.2)	6 (9.1)	13 (9.2)	0.976
Episiotomy performed, yes (N = 223)	73 (32.7)	33 (45.8)	40 (26.5)	0.004
Perineum supported, yes (N = 228)	191 (83.8)	42 (58.3)	149 (95.5)	0.001
Presentation (N = 239)				1.000
Cephalic	238 (99.6)	80 (100.0)	158 (99.4)
Breech	1 (0.4)	0 (0.0)	1 (0.6)
Position (N = 237)				1.000
Occipital anterior	235 (99.2)	79 (100.0)	156 (98.7)
Occipital posterior	1 (0.4)	0 (0.0)	1 (0.6)
Sacrum anterior	1 (0.4)	0 (0.0)	1 (0.6)
Mode of delivery (N = 233)				0.829
Spontaneous vertex	227 (97.4)	77 (96.5)	150 (97.4)
Vacuum extraction	4 (1.7)	2 (2.5)	2 (1.3)
Spontaneous breech	1 (0.4)	0 (0.0)	1 (0.7)
Assisted breech	1 (0.4)	0 (0.0)	1 (0.7)
Head circumference, cm, mean (SD)	36.6 (±1.9)	36.6 (±1.9)	36.6 (±1.9)	0.912
HIV status, positive (N = 237)	34 (14.35)	10 (12.7)	24 (15.2)	0.836