This study shows that the factors associated with the use of modern contraception vary significantly across all regions in Indonesia, where the mothers’ age, number of living children, and ideal number of children were the general factors associated with the use of contraception in all regions. Based on the results of this study, the highest prevalence of contraceptive use was in the Kalimantan region, and the lowest was in the Papua region. This result aligns with the 2017 IDHA and 2017 National Population and Family Planning Board report. In the North Kalimantan region, the birth rate decreased between 2015 and 2045, and many residents are aware of the family planning program by delaying the age of marriage and birth spacing and limiting the number of births [22].
The Papua region had the lowest prevalence of contraceptive use. The low contraceptive use can be attributed to factors such as location, level of education, income index, and access to information. This result aligns with research conducted by Teplitskaya, Ross, and Dutta [23] that found that women in eastern Indonesia experience obstacles in accessing family planning services, live far away from health facilities, and lack competent health workers.
In all regions, mothers in the 20–35 years age group were more likely to use modern contraception than mothers aged < 20 and ≥ 35 years. This result supports the research finding in Ghana, which found that older women were less concerned about using modern contraceptives [24] as older age is often associated with lower fecundity and reduced sexual activity [25]. A study by Nasution [26] found that mothers over 30 were less likely to use contraception as women of this age tend to have the intention to stop their fertility. After all, if they have had enough children, there is no desire to have any more [27]. Other researchers have also stated that the majority of women aged > 35 years do not use modern contraception more than women aged 20–35 years [28].
Mothers’ education level was found to have a relationship with the use of modern contraception in all regions except the Maluku Islands and Papua. These results align with a study by Tukue et al. [29] in Edaga-Hamus, Ethiopia, which found that women with higher education were less likely to use contraception than women with lower education. Research conducted by Naluri and Prasetyo [30] stated that women with higher education tend to get jobs and increased incomes; therefore, these women do not have problems with children because they can support their families. Individuals with higher education have broader knowledge, but that does not mean individuals with lower education must also have less understanding because increased knowledge does not only come from formal education but also from non-formal education [31].
Mothers’ employment status was found to have a relationship with the use of modern contraception in the Sumatra and Java-Bali regions. These results are in line with Seyife et al. [32], who also stated that women’s employment status had a significant effect on their use of modern contraception. Compared to those unemployed, women engaged in different occupations have more opportunities to share information and experiences about modern contraception with their co-workers. with their co-workers. Therefore, working women have more knowledge and awareness when choosing modern contraception. These women tend not to use certain types of contraception because of the side effects that can interfere with their work. Working women tend not to use contraception because certain types of contraception can cause side effects that interfere with women's work [28].
The number of living children was found to have a relationship with the use of modern contraception in all regions of Indonesia. These results align with a study by Alemayehu et al. [33] stating that women with six or more children were more likely to use contraception than those who did not have children. A possible reason for this might be that women who have six children have fulfilled their desire to have children. Other researchers have suggested that when the ideal family size is reached, women will choose to use contraception. Therefore, women with more living children tend to use contraception because they have reached their ideal family size [34].
The ideal number of children was found to have a relationship with the use of modern contraception across all regions in Indonesia. In line with research by Oumer, Manaye, and Mengistu, [35] women with fewer ideal children are more likely to use modern contraceptives than those with more ideal children. Similar research was also conducted by Oktabriani et al. [36], and they found that the highest use of contraception was by the group of women whose ideal number of children was two or less compared to those whose ideal number of children was more than two.
Economic status was found to have a relationship with contraceptive use in all regions except Kalimantan and the Maluku Islands. This finding is in line with a study by Wasswa, Kabagenyi, and Ariho [37], which found that middle- or upper-class women have a higher chance of using modern contraception than women in the lower class. Such a difference is because women from wealthy households may have better access to modern contraceptives than women from low-income families. Other studies have also revealed that women in the highest wealth index category most likely use modern contraception compared to different economic strata [38].
Insurance ownership was also found to have a relationship with the use of modern contraception in the Sulawesi region. A similar finding is revealed by Kaafi and Nurwahyuni [39] that women of childbearing age with health insurance were 1.14 times more likely to use contraception than women who did not have health insurance. In accessing family planning services, National Health Insurance participants seek to regulate their birth spacing and ideal childbirth age. The use of Social Security Agency of Health cards was relatively low for contraception due to the majority of people not knowing how the cards work for family planning services [40].