Characterization and risk factors for unexplained female infertility in Sudan: A case-control study

Table 2 History and clinical characteristics of study participants, n (%)

Variables	Categories	Cases (n = 210), N%	Controls (n = 190), N%	Effect size Cramer’s V	P value
Duration of infertility/marriage duration (yr)		Median = 3; Range = 1-15; IQR (3.75)	Median = 4; Range = 3-20; IQR (2)	NC	NC
Previous miscarriage or abortion	Yes	12 (5.71)	25 (13.16)	0.133	0.02
	No	198 (94.29)	165 (86.84)
Number of miscarriages or abortions	Never	198 (94.29)	165 (86.84)	0.164	0.08
	1	6 (2.86)	13 (6.84)
	2	4 (1.9)	6 (3.16)
	3	1 (0.48)	4 (2.1)
	4	0 (0)	2 (1.05)
	5	1 (0.48)	0 (0)
Family history of infertility	Yes	59 (28.1)	12 (6.3)	0.293	0.001
	No	151 (71.9)	178 (93.7)
Family history of Unexplained infertility	Yes	29 (13.8)	3 (1.6)	0.233	0.001
	No	181 (86.2)	187 (98.4)
Use of modern contraceptives/yr	Never	136 (64.8)	119 (62.6)	0.093	0.28
	0-3 yr	53 (25.2)	60 (31.6)
	4-6 yr	16 (7.6)	9 (4.7)
	More than 6 yr	5 (2.4)	2 (1.1)
	Not in use now	0 (0)	0 (0)
Alcohol consumption	Yes	0 (0)	0 (0)	NE	NE
	Not at all	210 (100)	190 (100)
	Stopped taking	0 (0)	0 (0)
Smoking1	Not at all	181 (86.2)	174 (91.6)	0.093	0.54
	< 1 yr	1 (0.48)	1 (0.53)
	1-2 yr	6 (2.9)	3 (1.6)
	2-3 yr	9 (4.3)	5 (2.6)
	> 4	13 (6.2)	7 (3.7)
Caffeine consumption (cup/d)2	No consume	8 (3.8)	6 (3.2)	0.063	0.72
	Low consume	68 (32.4)	69 (36.3)
	Moderate consume	66 (31.4)	51 (26.8)
	High consume	68 (32.4)	64 (33.7)
Physical activity level	Very active	43 (22.6)	38 (18.1)	0.083	0.26
	Moderately active	51 (26.9)	71 (33.8)
	Sedentary	96 (50.5)	101 (48.1)

¹The reported tobacco smoking in this study was in two forms [cigarettes, and shisha (water pipe)].

²Caffeine consumption was based only on liquid sources of caffeine (Tea, coffee, Sodas, and Energy Drinks).

³In the last column to the right, bold values indicate a significant level at P < 0.05. Cramer’s V effect size was classified according to Kim (2017)(41) as small effect size.

⁴Medium effect size.

Differences between groups were compared with chi-square test. Estimated effect sizes were calculated using Cramer’s V statistic which is expressed as mean. Physical activity level follows the WHO classification[38]. IQR: Interquartile range; n: Sample size; NC: Not Comparable due to dissimilar data; NE: Not evaluated in STATA due to zero value in one of the study groups.