Introduction

Eswatini has a generalized epidemic with an HIV prevalence of 26% in 2007 [1] and 27% among adults aged 15–49 years, 20.4% among males, and 32.5% among females in 2016 [2]. The HIV incidence was estimated at 2.4% (95% CI: 2.1, 2.8) in 2016, higher among women 3.1% (95% CI: 2.6, 3.7) versus 1.7% (95% CI: 1.3, 2.1) in men [2, 3].

To reduce the incidence of HIV infection, a combination of approaches have been implemented in Eswatini. In 2011, a substantial scale-up to access antiretroviral therapy (ART) and testing through the treat all approach as advised by the World Health Organization resulted in a decrease in the number of HIV infections [4]. In 2014, Eswatini achieved a 44% reduction of HIV infection from 23.1 new infections to 15.4 per 1,000 adults aged 15–49 years in 2018 [2]. The ART coverage among adults aged 15–49 years increased from 34% in 2010 to 74.1% in 2016 with a reduction of HIV incidence of 43.6% (95% CI: 39.71, 46.36) and HIV related deaths of 56.2% (95% CI: 54.06, 58.92) [5]. Pre-exposure and post-exposure prophylaxis have also been scaled up, to maximize prevention efforts for HIV infection in Eswatini [5]. Since 2009, voluntary medical male circumcision (VMMC) has been a priority in Eswatini. The prevalence of VMMC improved from 14% in 2008 [6] to 25% in 2014 [7]. Despite the several interventions being implemented HIV infection is still disconcertingly high in Eswatini, especially among women [2, 8–12].

Behaviors such as unprotected sexual intercourse, inconsistent condom use, poverty and unemployment, multiple sexual partners, substance abuse, and early sexual debut have been documented to sustain the transmission of HIV [13–15]. It has long been documented that behavioral patterns in sexual relationships play a significant role in the transmission of HIV/AIDS and STIs [13, 16–18]. Some public health experts believe that multiple concurrent partnerships and high partner acquisition are the main drivers of the persistent and high incidence of HIV in Sub-Saharan Africa (SSA) [19, 20]. Evidence suggests that multiple sexual partners during acute HIV infection are a driving force in heterosexually transmitted HIV epidemics in SSA, including Eswatini [6, 21–23]. Multiple sexual partnerships coupled with inconsistent condom use increase the risk of HIV acquisition [3, 23]. Women are biologically more at risk of contracting HIV and STIs than men and the risk of transmission from men to women is high compared to men [24, 25]. Developing countries have a high burden of STIs posing a major health burden for women aged 15–49 years who are more likely to be asymptomatic and have serious complications, such as pelvic inflammatory disease, leading to infertility and ectopic pregnancies [26]. Correspondingly, there is a need for a better understanding of the risk factors for multiple sexual partners among women in the context of Eswatini. Considerable research has explored the association of individual and household level factors on multiple sexual partners among women in a number of SSA countries [6, 17, 27, 28]. Very few attempts have been made to investigate community-level factors that influence the lifetime number of sexual partners, especially in Eswatini. This limitation is essential since the sexual behaviour of an individual is not purely dependent on individuals’ choices or circumstances but also determined by the aggregate level (social environment) factors in which individuals are nested in communities [1, 29]. Therefore, this study aimed to investigate the association between a range of individual and community variables on the lifetime number of sexual partners in Eswatini.

Methods

Study design and sampling

The EMICS was representative and collected information on households, men, women, and children. The sampling frame of the enumeration was based on the 2007 Eswatini Population and Housing Census [30]. In the EMICS, a two-staged sampling technique was applied. First, enumeration areas (EAs), also known as the primary sampling units (PSUs), were selected. Second, households were selected stratified by the rural and urban residence and the four regions of the country, which are Manzini, Hhohho, Shiselweni, and Lubombo. A detailed description of the sampling approach can be found in the 2014 EMICS [7].

A total of 5001 women aged 15–49 years identified in the households were eligible for the survey interview. However, a total of 4,762 completed the survey (Table 1). We restricted our analysis to 2,832 women aged 15–49 years with complete data on their lifetime number of sexual partners and other characteristics. Data collection for the 2014 EMICS was conducted between July and November 2014.

Table 1

Household response rates and women response rates.

	Place of residence
Households	Urban	Rural	Total
Households selected	1,351	3,860	5,211
Households interviewed	1,286	3,579	4,865
Household response rate	95.2%	95.7%	93.4%
Women age 15–49
Number of eligible women	1,128	3,873	5,001
Number interviewed	1076	3686	4,762
Response rate	95.4%	95.2%	95.2

Results

The sample distribution, mean lifetime number of sexual partners, and bivariable results are presented in Table 2. The overall mean number of lifetime sexual partners was 2.78 (95% CI: 2.66, 2.91) among women. The mean number of lifetime sexual partners was lower among women aged 15–19 years and higher for those aged 20 years and older. The mean number of reported lifetime sexual partners was nearly equal by women education level and was higher among formerly married versus currently married. The mean number of reported lifetime sexual partners decreased with the age of sexual debut. For example, women who had sexual intercourse when they were 18 and older had a mean of 2.50 versus 3.47 among those aged less than 15 years and 3.04 among those aged 15–19 years. The mean number of reported lifetime sexual partners was higher among women that did not stay with their sons and daughters versus those that lived with their sons and daughters. The mean number of reported lifetime sexual partners was higher among women that resided in households that were classified as rich versus those that were poor. Women that lived in urban areas reported a higher mean number of reported lifetime sexual partners compared to those that resided in rural areas. The mean number of reported lifetime sexual partners was nearly equal across all four regions of residence, although the Manzini and Hhohho regions had slightly higher. Women that were from communities with a low proportion of households classified as poorest and poor quantiles had a higher mean number of sexual partners when compared to those from communities with a high proportion of households classified as poorest and poor quantiles.

Table 2

Individual characteristics by lifetime number of sexual partners.

Variables	n (%)	Mean (standard error)	95%CI	URRs (95%CI)
Individual-level factors
Lifetime number of sexual partners	n = 2,832	2.78 (0.06)	2.66,2.91
Age
15–19	134 (4.4)	1.63 (0.10)	1.43,1.84	1
20–24	504 (17.7)	2.44 (2.17)	2.17,2.70	1.39 (1.25,1.55)*
25–29	588 (21.2)	2.91 (0.99)	2.72,3.10	1.74 (1.57,1.94)*
30–34	562 (21.4)	2.80 (0.12)	2.56,3.04	1.74 (1.57,1.94)*
35–39	433 (14.8)	3.16 (0.14)	2.89,3.43	1.90 (1.71,2.12)*
40–44	362 (12.3)	2.89 (0.12)	2,65,3.13	1.81 (1.61,2.02)*
45–49	249 (8.2)	2.92 (0.129)	2.67,3.18	1.78 (1.58,2.00)*
Education level
No education	167 (5.1)	2.93 (0.26)	2.42,3.45	1
Primary	765 (24.9)	2.79 (0.91)	2.61,2.97	0.94 (0.84,1.04)
Secondary	968 (34.7)	2.84 (0.11)	2.63,3.05	0.89 (0.81,0.99)*
High school	651 (24.5)	2.65 (0.09)	2.47,2.84	0.82 (0.74,0.91)*
Tertiary	281 (10.9)	2.79 (0.17)	2.45,3.13	0.92 (0.82,1.04)
Marital status
Currently married	1750 (60.4)	2.48 (0.078)	2.33,2.64	1
Formerly married	256 (10.5)	4.25 (0.20)	3.85,4.64	1.52 (1.43,1.63)*
Never married	826 (29.2)	2.87 (0.86)	2.70,3.04	1.06 (1.01,1.12)*
Age at first sexual intercourse (in years)
<15	198 (6.5)	3.47 (0.24)	3.01,3.94	1
15–17	1175 (40.4)	3.04 (0.08)	2.88,3.19	0.87 (0.80,0.94)*
18 and older	1459 (53.1)	2.50 (0.08)	2.34,2.67	0.71 (0.65,0.77)*
Condom used at last sexual intercourse
Yes	1508 (56.2)	2.99 (0.08)	2.84,3.14	1
No	1324 (43.8)	2.51 (0.07)	2.37,2.65	0.88 (0.83,0.92)*
Lived with sons and daughters
Yes	2351 (80.9)	2.65 (0.06)	2.53,2.78	1
No	481 (19.1)	3.33 (0.12)	3.10,3.57	1.20 (1.13,1.28)*
Household wealth index
Poor	1171 (34.0)	2.49 (0.07)	2.36,2.62	1
Middle	615 (19.6)	2.77 (0.10)	2.58,2.95	1.04 (0.97,1.10)
Rich	1046 (46.4)	3.00 (0.10)	2.80,3.20	1.09 (1.03,1.16)*
Community factors
Place of residence
Rural	2153 (65.4)	2.58 (0.05	2.48,268	1.21 (1.14,1.29)*
Urban	679 (34.6)	3.16 (0.13)	2.91,3.42	1
Region
Hhohho	734 (23.5)	2.84 (0.08)	2.68,3.00	1
Manzini	776 (41.2)	2.94 (0.12)	2.70,3.18	0.98 (0.91,1.05)
Shiselweni	743 (16.6)	2.45 (0.92)	2.27,2.63	0.86 (0.79,0.93)*
Lubombo	579 (18.7)	2.65 (2.39)	2.39,2.91	0.91 (0.84,0.99)*
Proportion of women from households classified as poorest and poor in the community
Low	1387 (57.8)	2.99 (0.09)	2.82,3.17	1
High	1445 (42.2)	2.49 (0.06)	2.36,2.62	0.85 (0.81,0.90)*

The bivariable results are also shown in Table 2. All the individual and community level factors were significantly associated with the reported lifetime number of sexual partners in the unadjusted models.

Multivariable multilevel model results

The random and fixed effects results are shown in Table 3. After controlling for both individual and community factors (model 3), women’s age, marital status, age at first sexual intercourse, condom use at last sexual intercourse, and women lived with sons and daughters were associated with the reported lifetime number of sexual partners. Women aged 20–24 (ARR = 1.51, 95% CI:1.29, 1.76), 25–29 (ARR = 2.01, 95% CI:1.73, 2.34), 30–34 (ARR = 1.99, 95% CI: 1.70, 2.32), 35–39 (ARR = 2.17, 95% CI:1.85, 2.54), 40–44 (ARR = 2.16, 95% CI: 1.84, 2.54), and 45–49 (ARR = 2.10, 95% CI: 1.77, 2.48) reported more lifetime sexual partners compared to women aged 15–19 years. Those that were formerly married, ARR = 1.68 (95% CI:1.55, 1.81) and never married, ARR = 1.34 (95% CI: 1.26, 1.43) reported more lifetime sexual partners compared to currently married women. After controlling for other factors in the model, women that were aged 15–17 years and 18 and older at sexual debut reported fewer lifetime sexual partners (ARR = 0.86, 95% CI: 0.79, 0.95) and (ARR = 0.67, 95% CI: 0.61, 0.74) respectively compared to those that were aged less than 15 years. Women that did not use a condom at last sexual intercourse reported fewer lifetime sexual partners (ARR = 0.91, 95% CI: 0.86, 0.95) compared to those that used a condom at last sexual intercourse. Relative to women that lived with their sons and daughters, those that did not live with their sons and daughters reported more lifetime sexual partners (ARR = 1.12, 95% CI: 1.05, 1.19). At the community level, women that lived in the Shiselweni and Lubombo region reported fewer lifetime sexual partners (ARR = 0.87, 95% CI:0.80, 0.93) and (ARR = 0.90, 95% CI: 0.83, 0.97) respectively compared to those residents in the Hhohho region.

Table 3

Individual and community-level factors and lifetime number of sexual partners.

Fixed effects	Model 0	Model 1	Model 2	Model 3
Individual level factors	ARR (95%CI)	ARR (95%CI)	ARR (95%CI)	ARR (95%CI)
Age
15–19		1		1
20–24		1.51 (1.29,1.76)*		1.51 (1.29,1.76)*
25–29		2.01 (1.73,2.35)*		2.01 (1.73,2.34)*
30–34		1.99 (1.71,2.33)*		1.99 (1.70,2.32)*
35–39		2.18 (1.86,2.55)*		2.17 (1.85,2.54)*
40–44		2.16 (1.84,2.54)*		2.16 (1.84,2.54)*
45–49		2.09 (1.77,2.48)*		2.10 (1.77,2.48)*
Education level
No education		1		1
Primary		1.00 (0.90,1.12)		1.00 (0.90,1.12)
Secondary		1.01 (0.91,1.13)		1.02 (0.91,1.14)
High school		0.94 (0.84,1.06)		0.95 (0.84,1.07)
Tertiary		0.97 (0.84,1.11)		0.97 (0.85,1.11)
Marital status
Currently married		1		1
Formerly married		1.68 (1.56,1.81)*		1.68 (1.55,1.81)*
Never married		1.34 (1.26,1.43)*		1.34 (1.26,1.43)*
Age at first sexual intercourse (in years)
<15		1		1
15–17		0.87 (0.79,0.95)*		0.86 (0.79,0.95)*
18 and older		0.67 (0.61,0.74)*		0.67 (0.61,0.74)*
Condom used at last sexual intercourse
Yes		1		1
No		0.90 (0.86,0.95)*		0.91 (0.86,0.95)*
Lived with sons and daughters
Yes		1		1
No		1.12 (1.05,1.19)*		1.12 (1.05,1.19)*
Household wealth index
Poor		1		1
Middle		1.08 (1.01,1.16)*		1.05 (0.98,1.13)
Rich		1.16 (1.08,1.24)*		1.07 (0.99,1.16)
Community factors
Place of residence
Rural			0.88 (0.81,0.96)*	0.95 (0.88,1.02)
Urban			1	1
Region
Hhohho			1	1
Manzini			0.98 (0.90,1.06)	0.94 (0.87,1.01)
Shiselweni			0.88 (0.81,0.96)*	0.87 (0.80,0.93)*
Lubombo			0.93 (0.84,1.01)	0.90 (0.83,0.97)*
Proportion of households classified as poorest and poor in the community
Low			1	1
High			0.92 (0.85,0.99)*	0.94 (0.88,1.01)
Random effects	Empty	Individual	Community	Full model
Community variance	0.039 (0.01)*	0.018 (0.05)*	0.027 (0.01)*	0.011 (0.005)*
Log-likelihood	-5372.04	-5116.22	-5351.45	-5103.95
PVC	Reference	61.97	31.72	71.43
AIC	10750.07	10274.4	10718.9	10259.9
N	2,832	2,832	2,832	2,832

Notes. SE-standard error, AIC-Akaike's information criterion, PCV-proportion change in variance, ARR–Adjusted rate ratio, CI: Confidence interval

* Significant at p-value <0.05.

Table 3 also showed the results of the random effects. There was a significant variation of the lifetime number of sexual partners (τ = 0.039, p<0.001) across communities (Model 0), justifying the use of the multilevel model in our analysis. The variance remained significant even after controlling for individual and community-level factors (τ = 0.111, p<0.004) (model 4). The results revealed that the variation of the lifetime number of sexual partners was a result of the composition of communities by individual and community-level factors. The model fit statistics revealed that the Akaike information criterion (AIC) reduced when combining individual and community level factors in one model, indicating that the final model fitted the data well when compared to the other models. Therefore, model 4 was chosen to predict the number of lifetime sexual partners among women.

Discussion

We examined the determinants of the lifetime number of sexual partners using a nationally representative sample of women for a better understanding of the predictors of lifetime number of sexual partners. We found that the mean number of lifetime sexual partners was 2.78 among women. Our findings revealed that a majority of women have multiple sexual partners in Eswatini and a number of factors were associated with the practice. Our results are comparable to multicountry studies done in SSA and Africa in general, that found women to have a mean of 2 to 3 lifetime sexual partners [19, 40]. Other studies conducted in SSA found that multiple sexual partnerships predispose women to the transmission and acquisition of STIs including HIV/AIDS [27, 30, 40].

We found that at the individual level, maternal age, marital status, age at first sexual intercourse, condom used at last sexual intercourse, lived with sons and daughters were associated with lifetime number of sexual partners. At the community level, only the region of residence was associated with the lifetime number of sexual partners. Multiple sexual partnership presents a health risk for the transmission of HIV and sexually transmitted infections; hence the results shared light for the strengthening of health promotion and sexual behavior educational programs among women aged 15–49 in Eswatini.

Predictably, the age of the women was positively associated with the number of lifetime sexual partners. Our results are in agreement with the literature [19, 40, 41]. The plausible explanation could be that older women accumulate more sexual partners as they get older.

Similar to other studies, we found that women that were never married and formerly married reported more lifetime sexual partners when compared to married women [27, 42]. Numerous studies reported that being married is associated with a wide range of health benefits [34, 43, 44]. According to the marital resources model, individuals that are married have better financial support, experience less stress and mortality [45]. Married individuals may be more likely to practice healthy behaviors especially women and may motivate each other as a couple to stay loyal to one another [46]. Formerly married or never-married women may have freedom from marital obligations and also more likely to participate in sexual networks for their survival and economic reasons [19].

We found that women that engaged in sexual intercourse when they were aged less than 15 years reported more lifetime number of sexual partners. In South Africa, the youth that engaged in early sexual debut reported more lifetime sexual partners [47]. Early sexual intercourse predisposes individuals to numerous negative health outcomes including STIs and HIV [48]. This may be because women that engaged in early sexual debut have a longer sexual duration that can increase the risk for HIV transmission and STIs [49, 50].

Women who did not use a condom during their last sexual intercourse reported few lifetime sexual partners. A plausible explanation for the finding could be that in this study, the majority of the women were married (see Table 2) supporting the assertion that a majority of people use condoms during casual contact outside their ongoing relationships [51, 52]. People with multiple sexual partners turn to have a higher frequency of condom use than people with a single partner [52]. Our results contradict those of the prior literature [19, 20], that people with multiple sexual partners have a higher risk to contract HIV, and this raises questions about factors like condom use that may be important modifiers of HIV risk in the context of multiple partnerships.

Several studies found that people from poor households had a greater number of sexual partners than those from richer households [33, 53, 54]. Contrary other studies found that wealthier people have a higher risk of exposure to HIV due to concurrent and multiple sexual behaviors [55, 56]. We found no significant difference in the women number of sexual partners by household wealth status.

Of particular interest are the effects of community-level factors in predicting the reported number of sexual partners among women in Eswatini. Community-level factors are important to explain the disparities that exist among individuals in communities [57, 58]. We found that women that were residents in the Shiselweni and Lubombo region reported fewer sexual partners than those in the Hhohho region. The Lubombo and Shiselweni region are the poorest regions in Eswatini compared to Manzini and Hhohho [59, 60]. In traditional communities’ women are more likely to marry early which reduces exposure to many sexual partners outside marriage.

In Nigeria women that were residents in communities that had a low and middle socioeconomic status were less likely to have reported multiple sexual partners relative to those resident in communities with higher socioeconomic status [58]. We found no significant variation in the reported number of sexual partners by community poverty. The results imply that community poverty may not be a factor that predicts multiple partnerships in Eswatini, but potentially other community factors.

Conclusion

Applying the multilevel methodology, the study demonstrated that women aged 20 and older, formerly and never married, had sexual debut when they were less than 15 years reported more lifetime sexual partners. Fewer lifetime sexual partners were reported by women that did not use a condom during their last sexual encounter, lived with their sons and daughters, and were residents in the Shiselweni and Lubombo regions. Furthermore, a significant variation of the risk of the reported lifetime number of sexual partners was observed at the community level. The study has implications for policy, that behavioral change and sexual behavior strategies and programs should also target the social context independent of the individual factors. Sexual programs and health promotion education should go beyond the individualistic model to operate at the community level. Interventions that aim to influence early sexual debut among the youth could potentially reduce the number of lifetime sexual partners, which might reduce the risk of HIV acquisition if it concurs with other protective behaviors, such as condom use.