This study was a hospital-based cross-sectional study carried out in the Kumba Regional Hospital Annex, and the Presbyterian General Hospital, South West Region of Cameroon from 1^st January 2023 to 31^st May 2023.

The vaccination unit of KRHA comprises of a unit head and 7 nurses. Vaccination is done following the EPI calendar. It receives about 120 children/month for BCG, and about 60 children/month for the other vaccines. It receives children across the Kumba Health District. The vaccination days are from Mondays to Fridays, but mainly Tuesdays and Thursdays.

The vaccination unit of the PGH comprises of a unit head and 4 nurses, and a supervisor from the health district. It covers children mainly from the southern part of the health district. Vaccination is done following the EPI calendar. The vaccination days are Tuesdays and Fridays. It receives about 60 children/month for vaccination.

During the days for vaccination, we started by giving a talk on cryptorchidism, laying emphasis on its complications and also assisted the nurses in the vaccination process. The ANC unit was beside the vaccination center, hence pregnant women also benefited from the health talk.

The study population was children aged 0 - 5 years coming for vaccination in the Kumba Regional Hospital Annex and the Presbyterian General Hospital.

Sample size determination

The sample size was calculated using the Cochran’s formula.

$n=\frac{Z^{2}p\left(1-P\right)}{{\text{e}}^2}$

where:

n = Minimum sample size;

Z = The standard normal variate at 95% confidence interval (Z-value = 1.96);

e = Error margin (5% or 0.05);

P = Expected prevalence of estimated population.

(Prevalence of cryptorchidism in Conakry) (Diallo et al., 2020) [6] .

Calculation

$n=\frac{\left(1.96\right)^2\left(0.0365\right)\left(1-0.0365\right)}{\left(0.05\right)^2}=53$

Using a prevalence of 3.65% from a previous study carried out in Conakry (Diallo et al., 2020) [6] , we had a minimum sample size of 53 participants. However, we enrolled 112 participants for this study.

Ethical approval was obtained from the institutional review board of the School of Health and Medical Sciences of CATUC, Bamenda. Administrative authorization was obtained from the provost of the School of Health and Medical Sciences of CATUC-Bamenda, and from the Directors of Kumba Regional Hospital Annex, and Presbyterian General Hospital Kumba. Following these approvals, we went to the vaccination units of these hospitals for introduction and to begin data collection.

After obtaining ethical clearance from the School of Health and Medical Sciences of CATUC, Bamenda and the Directors of the various hospitals, women and their children were invited to take part in our study when they came for vaccination.

The mothers were thoroughly informed on the study, its aims, procedure, possible inconveniences, and confidentiality. Those who met the inclusion criteria and agreed to participate were then required to sign a consent form before being subjecting their children to our examination.

A questionnaire was used to record all the data and the following were of interest:

1) Socio-demographic data of the mother: Age, occupation and level of education.

2) Lifestyle during pregnancy:

Smoking (cigarettes/day), alcohol (drinks/week), and caffeine (mg/day).

3) Clinical parameters of the mother:

Height, weight, and parity before index pregnancy.

4) Clinical parameters of the child:

Age, birth weight, Gestational age at delivery, type of pregnancy, number of testes in the scrotum, and location of the left and right testes.

The date of the enrolment into the study was noted. Questionnaires were coded with numbers and the participants provided telephone numbers.

Information such as maternal age at delivery was taken from mother’s ID card. Information such as occupation and level of education was gotten verbally.

Information such as smoking (number of cigarettes smoked/day), alcohol (number of bottles of beers/week), and caffeine (type of coffee and the quantity taken/day).

The number of smoking was converted to pack/year’s using the formula: (number of sticks of cigarettes smoked per day ÷ 20) × (number of years of smoking).

The quantity of alcohol consumed was converted to units/week using the formula (vol of alcohol in mls) × (% of alcohol) ÷ 1000.

Caffeine was reported in mg/day, depending on the type of caffeine consumed. The one most commonly asked was Nescafe.

The weight and height were taken from the ANC records during the 3^rd trimester.

The BMI was calculated using the formula: weight (kg)/height (m²).

The parity before the index pregnancy was asked verbally and also checked in the ANC records.

The age of the child, birth weight, Gestational age at delivery and type of pregnancy were taken from the children’s vaccination cards.

The number of testes in the scrotum and the location of the left and right testis were gotten during our physical examinations, with the children lying in the supine position naked.

The data was coded, and the questionnaire was double-checked for completeness and consistency. The data was entered into Microsoft Excel 2016 and then imported to SPSS version 26 for analysis. Exploratory data analysis was done to check missing values and outliers.

Results were represented on tables and figures (pie charts) to ease organization and comprehension.

Bivariate analyses were done using chi-square test to determine independent factors that were significantly associated with cryptorchidism (maternal age at delivery, occupation, level of education).

$\frac{\text{Number of children with Cryptorchidism}}{\text{Total number of children examined}}\times 100$

The risk factors were assessed using Stepwise multivariate logistic regression analysis and adopting odds ratio (OR) estimates and confidence interval (95% CI) with p-values < 0.05, which was significant. 122 children coming for vaccination were recruited ( Figure 1 ) of which 10 were excluded because their guardians had <70% knowledge of the ANC and birth history of the children.

A total of 112 children and their mothers were recruited. As shown in Table 1 , 58.0% (n = 65) of the mothers were aged between 20 and 30 years, of which 43.7% (n = 50) were self-employed and 60.7% (n = 68) attended of the 112 children recruited, 53.6% (n = 60) where less than 6 months of age, of the 112 children recruited, 53.6% (n = 60) where less than 6 months of age, of which 3 were cryptorchid.

The majority of the mothers were overweight in the 3^rd trimester, i.e. 42% (n = 47) and about 15% (n = 15) didn’t know their weight and or height in the 3^rd trimester of pregnancy secondary education. Age of delivery of mother was 27.93 ± 6.116 ( Table 2 ).

Most of the women, 57.1% (n = 64) had a parity of less than 1 before the children recruited and about 7.1% (n = 8) had a parity of greater than or equal to 4 of the 38 children whose mothers were obese, 6 of them were cryptorchid.

Several socio-demographic factors were analyzed in relation to cryptorchidism as seen in Table 3 below, with a focus on identifying significant associations based on a p-value threshold of less than 0.2. The level of education of the mother emerged as a significant factor, with a p-value of 0.03, indicating that the educational background may influence the occurrence of cryptorchidism. Other factors, such as the age of the child category, alcohol consumption and occupation of the mother with p-values of 0.124, 0.104, and 0.152 respectively suggest a potential association that could be explored in future studies.

For the maternal and child factor related to cryptorchidism, as shown in Table 4 below, the number of testes in the scrotum shows a highly significant association with a p-value of less than 0.001. This indicates a strong relationship between the presence of testes in the scrotum and the occurrence of cryptorchidism. This stark contrast highlights the critical role of testicular presence in the scrotum as a determinant factor for cryptorchidism, suggesting that the absence of one or both testes is a significant risk factor for this condition. Other variables, such as BMI classification in the third trimester, demonstrate significant associations with cryptorchidism, as their p-values (0.165) were less than 0.2 and could be explored.

Cryptorchidism is the condition where one or both testicles fail to descend into the scrotum. As shown in Figure 2 below, the frequency of non-cryptorchid individuals is 101, representing 90% of the sample, while those with cryptorchidism account for 11 individuals, or 10%. This indicates that cryptorchidism affects a significant minority of the population, highlighting the importance of awareness and early detection. The condition can lead to various complications, including infertility and increased risk of testicular cancer, making it crucial for healthcare providers to monitor and manage cases effectively.

Figure 3 below presents the distribution of various locations of the right testes. The majority of the observations, accounting for 87.5% (98 cases), are categorized under scrotum, indicating that the right testes are predominantly located within the scrotal sac. A smaller proportion of cases are noted in other categories: high scrotal locations represent 5.4% (6 cases), while external orifice and nonpalpable locations account for 2.7% (3 cases) and 3.6% (4 cases), respectively. Additionally, there is one case (0.9%) classified as internal orifice. This data suggests that while most right testes are found in the expected scrotal position, there are a few instances of atypical locations, which may warrant further clinical investigation.

As seen Figure 4 below, majority of cases, accounting for 85.7% (96 instances), are classified as scrotum, indicating that the left testes are predominantly found in the scrotal position. A smaller proportion, 8% (9 instances), is identified as high scrotal, suggesting that these testes are located higher than the typical scrotal position. Additionally, 3.6% (4 instances) are categorized as nonpalpable, meaning these testes could not be felt during examination, while 2.7% (3 instances) are located at the internal orifice. This data highlights the prevalence of scrotal positioning for the left testes while also acknowledging the presence of cases with atypical locations.

Further analysis was done using multiple logistic regression with the significant values < 0.05.

As seen in Table 5 below, occupation, more particularly self-employment, was associated with cryptorchidism with odds ratio of 10.689 (1.182; 96.65) and p-value of 0.035. The odds ratio of 10.689 suggests that self-employed individuals are over ten times more likely to have a child with cryptorchidism compared to those who are employed.

In our study, the mean age of the mothers was 27.95 ± 6.12, which presents the average age of peak fertility in women. This is consistent with the study carried out by Carbone et al. between 1998-2002 in Italy [9] and Hougaard et al. between 1988-1994 in Denmark [10] . We discovered there was no significant association between maternal age and cryptorchidism. These findings were similar to those reported by Hougaard et al. between 1988-1994 in Denmark [10] and Berkowitz et al. in 1990 in New York [11] . However, some authors like McGlynn et al. between 1959-1965 in USA [12] found an association between older women (>30 years) [13] , between younger women (<20 years) and cryptorchidism respectively due to differences in circulating levels of estrogen, but this evidence didn’t reach statistical significance.

According to our study, 44.6% of the mothers were self-employed and 25% were employed, which revealed an association between mothers who are self-employed and their sons having cryptorchidism with an aOR (10.689, p = 0.0350); which means Children born by mothers who are self-employed are 10times more likely to have cryptorchidism than children whose mothers are employed in Kumba. These findings were in line with those discovered by Berkowitz et al. [11] between 1980-1960 in Hungary, a lower maternal standard of living.

The most probable reason of this could be because the left testes start descending before the right and the left testes is usually lower than the right because of a force acting on which can result in intrauterine growth restriction, preterm deliveries.

However, these findings were different from those discovered by Damgaard et al. between 1997-2001 in Copenhagen and between 1997-1999 in Finland and Berkowitz et al. in 1996 in New York [11] , which didn’t show an association between occupational class and cryptorchidism. These discrepancies could be explained by a smaller sample size and shorter duration of our study.

Majority of the mothers, 60.7% ended secondary education and 24.1% attended university education. In our study, we didn’t find any association between level of education and cryptorchidism. These findings were in line with those reported by Li et al. between 1964-2010 in Sweden [14] and Berkowitz et al. in 1996 in New York [11] .

In our study, we found that the prevalence of cryptorchidism was 9.8%. This value was high when compared to the 3.5 cases/year reported by Mouafo et al. between 2008-2016 in Yaoundé [15] , 3.6% by Diallo et al. in 2009 in Conakry [16] , and 1.52% by Kumanov et al. in 2011 in Bulgaria [8] . This discrepancy could be explained by the fact more than half of our study population were children below 6 months, and there is a decrease in trend in prevalence as age increases, As described by Scorer in 1964 [17] (4.2%, 0.97%, 0.78%), John Radcliffe Hospital cryptorchidism group between 1986-1992 (5.01%, 1.78%) [18] , and Berkowitz et al. (3.68%, 1.00%, 1.06%) [11] that there’s a decreasing prevalence from birth, 3 months and 1 year respectively. As described by Scorer, congenital cryptorchidism resolves spontaneously and this descent occurs mostly during the first months of life, when the endogenous testosterone secretion briefly increases, thus a lower prevalence is usually reported from 3 to 12 months of life.

In our study, 2/3^rd of the children with cryptorchidism were unilateral, of which 57% were on the right. These findings were similar to those reported by Barthold et al. between 2011-2016 in DR Congo, and Favorito et al. [19] between 1996-2013 in Brazil.

It is known that an increase in body weight and fat tissue is associated with several abnormalities of sex steroid hormone balance, particularly in women of reproductive within the abdomen during the development and movement of abdominal viscera. This force is a positive intra-abdominal pressure, the center of which is on the left side of the median plane. Hence, the left kidney and testis are pushed to a farther distance than that of the right kidney and testis. Since the center of this pressure is on the left of the median plane, it fails to push the right kidney and right testis to the same levels as their left counterparts [20] .

Unfortunately, the definition of cryptorchidism is not uniform and therefore study results differ substantially even if the applied methodology is similar. There is no consensus among researchers on whether high scrotal testes should be counted as normally descended testes or abnormal.

In our study, majority of the women drank between 0 - 5 units of alcohol/week (1 - 3 bottles of beer/week). Alcohol consumption during pregnancy is suspected to modify sex hormone levels in utero, which are essential for the descent of the testes, as described by Steven et al. in the USA (2005). However, our results didn’t find an association between maternal alcohol consumption and cryptorchidism. Similar results were observed by Zhang et al., a meta-analysis study in USA (2015) [21] , Kjesgaard et al. between 1985-2012 in Denmark, Mongraw-Chaffin et al. between 1958-1967 in California. Damgaard et al. between 1997-2001 in Copenhagen and between 1997-1999 in Finland found an association between maternal alcohol consumption and cryptorchidism. This difference could be because Damgaard et al. considered only children less than 3 months in their study.

In our study, majority of the women were overweight or obese, i.e. according to the WHO standard for classification of BMI, underweight: <18.5 kg/m², normal weight: 18.5 - 24.9 kg/m², overweight: 25 - 29.9 kg/m² and obese: ≥30 kg/m² [22] .

Age as discovered by Pasquali et al. (2003) in Italy. Such alterations involve both androgens and estrogens and, overall, their carrier protein, sex hormone-binding globulin (SHBG), can affect testicular descent. However, in our study, we didn’t find an association between maternal BMI and cryptorchidism. This was similar to the results observed by Arendt et al. between 1992-2012 in Sweden, Adams et al. between 1992-2008 in Washington. However, Li et al. between 1964-2010 in Sweden [14] , and Berkowitz et al. in 1996in New York [11] found an association between maternal BMI and cryptorchidism, with children born by mothers with obesity during pregnancy likely to develop cryptorchidism. This difference could be explained by our small sample size and shorter study period, and we also relied on maternal information for obtaining weight during pregnancy and some turn to hide their real values.

It has been hypothesized that there is an association between parity before the index pregnancy and cryptorchidism, due to hormonal differences in nulliparous women compared with multiparous women [23] . Women in their first pregnancy have higher levels of free estradiol than in subsequent pregnancies, as described by Bernstein et al. in 1986, and mothers of cryptorchid boys have been found to have higher levels of free estradiol during the first trimester than mothers of boys with normal testicular descent, as described by Bernstein et al. in 1988. However, we didn’t find an association between parity before index pregnancy and cryptorchidism. This was similar to the discoveries made by Mori et al. in 1992 in Japan, Weidner et al. between 1983-1992 in Denmark and Wagner-Mahler between 2002-2005 in France. Biggs et al. in 2002 in Washington found a weak association between nulliparity and cryptorchidism, but it wasn’t statistically significant.

Low birth weight and gestational age at delivery have been reported by many authors as common risk factors of cryptorchidism. Testicular descent in humans is completed during the third trimester of pregnancy.