Study population
Our study population of 1920 participants consisted of residents of Ulaanbaatar city and four regions of Mongolia (Western, Eastern, Central and Khangai). The demographic and socio-economic characteristics of the participants are shown in Table 1.
Table 1. Demographic and socio-economic characteristics of study participants
Characteristics
|
Women
|
|
n
|
% of total
|
Number of participants
|
1920
|
100
|
Region
|
|
Ulaanbaatar
|
695
|
36.2
|
Eastern
|
163
|
8.5
|
Western
|
300
|
15.6
|
Khangai
|
395
|
20.5
|
Central
|
368
|
19.2
|
Age, years (Mean (SD))
|
32.57±6.61
|
BMI, kg/m2 (Mean (SD))
|
25.08±4.52
|
BMI, normal
|
1075
|
56
|
Overweight
|
555
|
28.9
|
Obese 1 class
|
246
|
12.8
|
Obese 2 class
|
35
|
1.8
|
Obese 3 class
|
9
|
0.5
|
Education
|
|
|
Primary school and below
|
212
|
11
|
Middle and high school
|
533
|
27.8
|
College and above
|
1175
|
61.2
|
Occupational ConditionsA
|
|
|
Normal
|
1663
|
86.6
|
Hazardous
|
257
|
13.4
|
Аnnual household income, MNT
|
|
|
<900000
|
1232
|
64.1
|
900000-1499999
|
518
|
27
|
>1500000
|
170
|
8.9
|
Tobacco use
|
|
|
NoB
|
1810
|
94.2
|
Yes
|
110
|
5.7
|
Alcohol consumption
|
|
|
No
|
715
|
37.2
|
YesC
|
1205
|
62.8
|
A According to Mongolian Labor Legislation, working conditions are divided into normal and hazardous
B Included people who never smoked’
C Included people who consumed alcohol within the past 12 months
Prevalence of infertility and patterns of region
Our study showed an infertility incidence of 7.2% (n=138), with primary infertility at 2.4% (n=46) and secondary infertility at 4.8% (n=92). Geographically the prevalence rate was as follows: Central region (8.2%, n=30), Khangai region (12.4%, n=49), Western region (7%, n=21), Eastern region (8%, n=13), Capital city Ulaanbaatar (3.6%, n=25) (Figure 1). In comparison with the sole urban area of Ulaanbaatar, the prevalence of infertility is significantly higher (p<0.001) amongst the rural population. As it is the only territory with a city status in Mongolia, we viewed it as the sole urban area.
Age related patterns of infertility
Our results show that there is a trend of secondary and overall infertility that increases with the women’s age. However, the same trend is present in primary infertility (Table 2). Women between 40-45 years of age had the highest rate of infertility (10.6%) compared to women of the 20-24 years of age who had a low infertility rate (1.4%) (n=40) (p<0.0001)
Table 2. Infertility prevalence age groups
Age group
|
Fertile women n=1782
|
Infertile women n=138
|
|
n
|
(%)
|
Overall infertility (%)
|
Primary infertility (%)
|
Secondary infertility (%)
|
20-24
|
216
|
11.3
|
1.4
|
1.4
|
0
|
25-29
|
482
|
25.1
|
5.4
|
2.9
|
2.5
|
30-34
|
471
|
24.5
|
7.9
|
3
|
4.9
|
35-39
|
373
|
19.4
|
8.6
|
1.6
|
7
|
40-45
|
378
|
19.7
|
10.6
|
2.4
|
8.2
|
Furthermore, when we map the prevalence of infertility as individual ages instead of groups, we notice a slow decline from ages 30-36 and then a sudden spike at ages 36-39 followed by a plateau until age 45. (Figure 2).
Risk factors for infertility
We then divided our participants into two groups of either infertile or fertile females. Adjusting for age we calculated for the association between infertility and risk factors among women.
We calculated the risk of infertility compared to the 20–24-year age group. Among the risk factors age was the most significant risk factor, with the risk increasing by 4 to 8-fold with each progressing age group. Social factors, such as: occupational conditions and monthly household income were not significent risk factors for infertility however alcohol consumption, obesity, rural living and lower levels of education were significant risk factors (Table 3)
Table 3. Infertility risk factors
Characteristic
|
Fertile woman n=1782
|
Infertility women n=138
|
Overall infertility n=138
|
Unadjusted OR (95 CI)
|
Age adjusted OR (95% CI)
|
Age groups (women) (%)
|
|
|
|
|
20-24
|
12
|
2.2
|
ref
|
|
25-29
|
25.6
|
18.8
|
4.04 (1.21-13.52)*
|
|
30-34
|
24.4
|
26.8
|
6.05 (1.84-19.85)**
|
|
35-39
|
19.1
|
23.2
|
6.66 (2.01-22.02)**
|
|
40-45
|
19
|
29
|
8.4 (2.56-27.5)***
|
|
Education
|
|
|
|
|
Primary school and below
|
10.9
|
13
|
1.44 (0.84-2.47)
|
1.18 (0.68-2.05)
|
Middle and high school
|
27.2
|
35.5
|
1.57 (1.07-2.3)**
|
1.4 (0.95-2.06)
|
College and above
|
62
|
51.4
|
ref
|
ref
|
Living region
|
|
|
|
|
City region
|
58.1
|
37.7
|
ref
|
ref
|
Rural region
|
41.9
|
62.3
|
2.29 (1.06-3.27)***
|
2.05 (1.38-3.04)***
|
BMI
|
|
|
|
|
Normal
|
53.4
|
45.7
|
ref
|
ref
|
Underweight
|
3.6
|
1.4
|
0.47 (0.11-1.99)
|
1.2 (0.08-17.34)
|
Pre-Obesity
|
27.9
|
31.3
|
1.41 (0.93-2.13)
|
0.93 (0.49-1.79)
|
Obesity
|
15.1
|
21.7
|
1.8 (1.17-2.98)**
|
2.9 (1.21-6.99)*
|
Physical activity
|
|
|
|
|
ActiveA
|
18
|
19.6
|
ref
|
ref
|
Inactive
|
82
|
80.4
|
0.9 (0.58-1.39)
|
0.89 (0.57-1.38)
|
Smoking
|
|
|
|
|
NoB
|
94.1
|
92
|
ref
|
ref
|
Yes
|
5.9
|
8
|
1.3 (0.72-2.64)
|
1.33 (0.69-2.55)
|
Alcohol consumption
|
|
|
|
|
NoC
|
37.2
|
23.2
|
ref
|
ref
|
Yes
|
62.8
|
76.8
|
2.05 (1.37-3.09)***
|
1.98 (1.31-2.98)***
|
*<0.05, **<0.01, ***<0.001
A Defined as at least 150–300 minutes of moderate-intensity aerobic physical activity or at least 75–150 minutes of vigorous-intensity aerobic physical activity; or an equivalent combination of moderate- and vigorous-intensity activity throughout the week
B Included people who have never smoked
C Included people who consumed alcohol within the past 12 months
We used the participant’s self-reported gynecological history to calculate the risks it imposed. We found the following risks associated with infertility: abnormal menstrual cycles 1.5 (CI 1.07-2.15 p<0.01 ), thyroid disease 1.6 (CI 0.98-2.79 p<0.05), intrauterine growth restriction 2.1 (CI 1.22-3.73 p<0.001), ectopic pregnancy 2.6 (CI 1.2-5.69 p<0.01) recurrent ectopic pregnancy 13.3 (CI 1.87-95.84 p<0.01), ovarian cysts 4.7 (CI 3.12-7.34 p<0.0001), endometrial polyps 4.1 (CI 1.99-8.59 p<0.0001), endometriosis 5.8 (CI 1.78-19.34 p<0.01), gynecological operative history (ovarian cystectomy, oophorectomy, salpingectomy, abortion, cesarean section) 2.6 (CI 1.72-4.06 p<0.0001) .
Clinical consultations for infertile couples
Of the total infertile participants (n=138), 77.5% (n=107) had sought clinical consultation regarding their infertility, while 22.5% (n=31) never sought any type of clinical consultation. Among the group that sought clinical consultation 29.7% (n=41) of the women had received some form of treatment, with hormonal therapy being most commonly used at 14.3%, followed by timing therapy at 4.5%, IUI therapy 0% and assisted reproductive technology ART at 0.8% (n=1) was scarce.