Prevalence and Determinants of HIV Infections among Pregnant Women Attending Antenatal Clinics in Iringa Municipality, Tanzania

INTRODUCTION

The prevalence of Human Immunodeficiency Virus (HIV) among pregnant women in Sub-Saharan Africa remains a significant public health concern, with the region accounting for a substantial proportion of the global burden of HIV. As of recent estimates, approximately 85% of all pregnant women living with HIV worldwide reside in this region [1]. The Joint United Nations Programme on HIV/AIDS (UNAIDS) report from 2017 indicated that the overall prevalence of HIV among individuals aged 15-49 in Sub-Saharan Africa was approximately 12.5% [1].

This statistic underscores the critical need for targeted interventions and healthcare services tailored to this vulnerable population. In Southern Sub-Saharan Africa, HIV prevalence rates among pregnant women are particularly alarming, often exceeding 20% in several countries [2]. Furthermore, a systematic review highlighted that Southern Africa bears a disproportionate burden of sexually transmitted infections (STIs), which can exacerbate the risks associated with HIV during pregnancy [3]. The pooled prevalence of STIs in this region is notably high, further complicating the health outcomes for pregnant women living with HIV.[3]

The younger women, those who have not disclosed their HIV status to their partners, and those not on antiretroviral therapy (ART) are at a higher risk of having unsuppressed viral loads [4]. This situation is critical as unsuppressed viral loads can lead to increased mother-to-child transmission of HIV, which remains a significant concern in the region [5]. The effectiveness of ART in preventing vertical transmission has been well-documented; however, barriers to adherence, such as stigma and lack of partner support, continue to hinder progress [6]. Moreover, socio-behavioral factors like gender inequality, poverty, partner violence, food insecurity, and cultural norms significantly influence HIV prevalence among pregnant women in Sub-Saharan Africa [7,8].

In Tanzania, the prevalence of HIV among pregnant women has shown varying trends over the years, reflecting both the impact of public health interventions and the ongoing challenges faced in combating the epidemic [9]. The prevalence of HIV among pregnant women was reported to be around 7% in specific municipalities with higher rates of transmission [10]. For over two decades, the HIV sentinel surveillance (HSS) among pregnant women attending antenatal clinics (ANC) has provided estimates of the burden and trend of HIV infections in Tanzania [11]. Six rounds of HSS have been done since 2000 and results indicate a decline in the prevalence of HIV infections among pregnant women in Tanzania from 9.6% in 2001 to 5.6% in 2011 [11,12].  Furthermore, the mentioned longitudinal study showed a decline in HIV prevalence among pregnant women in Tanzania from 2001 to 2011, attributed to effective public health initiatives like ART and prevention of mother-to-child transmission (PMTCT) programs [11]. Despite the progress made, challenges persist. A study highlighted that a significant proportion of HIV-positive pregnant women still face barriers to accessing ART, which is vital for reducing the risk of vertical transmission [12]. Additionally, the presence of co-infections, such as syphilis, which was found to affect 1.4% of pregnant women in Tanzania, poses additional risks for adverse pregnancy outcomes and complicates the management of HIV [13].

In the context of general public health, the Iringa region has consistently demonstrated high prevalence rates, as indicated in the reports from 2016-2017, which recorded a rate of 11.3%, and from 2022-2023, which noted a rate of 11.1%. This positions Iringa as the second-highest region after Njombe in both assessments [14]. Consequently, this study focused on assessing the prevalence of HIV and its determinants among pregnant women attending antenatal clinics in Iringa Municipality, Tanzania.

METHODS

Study area

The area of focus for this study is Iringa Municipality, located in the Iringa region of Tanzania. As the administrative capital, Iringa Municipal Council is one of five councils in the region, distinguished by its urban characteristics. The other councils include the Iringa District Council, Kilolo District Council, Mufindi District Council, and Mafinga Town Council. Iringa Municipality is bordered by the Iringa Rural and Kilolo district councils and is positioned between latitudes 7.7° and 7.875° south of the Equator, and longitudes 35.620° and 35.765° east of the Greenwich Meridian. The 2022 census reported that the municipality has a population of 202,490 residents [15,16].

Study design

The study conducted from June 12 to July 15, 2024, employed a quantitative cross-sectional analytical design to rigorously assess the prevalence of HIV and its associated factors among pregnant women receiving antenatal care in Iringa Municipality, Tanzania. This methodological approach facilitated the collection and analysis of data at a single time point, thereby enhancing the understanding of the epidemiological characteristics of HIV in this specific population.

Study population

The research targeted pregnant women who utilized antenatal care services in Iringa Municipality, Tanzania. Participants were required to meet specific inclusion criteria, which stipulated that they must be pregnant, have resided in Iringa Municipality for a minimum duration of six months, and be willing to provide informed consent for the study. Exclusion criteria encompassed individuals who were unable to provide informed consent due to cognitive or psychological impairments, as well as pregnant women who were transient visitors to the antenatal clinic without having established residency in the municipality for at least six months.

Sampling and sample size

Due to the limited availability of public hospitals and health centers, a deliberate choice was made to include all two available hospitals and four health centers in the municipality, along with a random selection of six public dispensaries. This method led to a total of twelve public healthcare facilities taking part in the study. Pregnant women were subsequently chosen at random from each facility. Cochran's formula was used to determine the sample size for the study.

Where; N = Minimum sample size

Z = Constant, standard normal deviation (1.96 for 95% confidence level)

P = Estimated proportion of the population (50% or 0.5) to maximize sample size in the absence of precise prevalence data

d = acceptable margin of error (4.2% or 0.042)

Therefore, the study in Iringa Municipality involved a total sample size of 545 pregnant women.

Data collection

All socio-demographic characteristics and HIV status data were recorded from the antenatal clinic cards of pregnant women during their current visits.

Data analysis

Data analysis was performed using version 26 of the Statistical Package for Social Sciences (SPSS), emphasizing frequencies and percentages to provide a foundational understanding of the dataset. Bivariate analyses, specifically chi-square tests, and p-values, were employed to identify significant associations between the predictor variables and HIV prevalence. However, further multivariate logistic regression was not performed due to the absence of significant relationships in the bivariate analysis and the presence of sparse data. The sparse data included several categories with either zero or very few positive cases of HIV, resulting in unstable and unreliable estimates. Consequently, the analysis concentrated on bivariate relationships to provide insights while acknowledging this limitation.

Definitions and scoring

The HIV prevalence serves as a proxy for estimating the overall HIV burden within the pregnant women population. For the general population, a prevalence rate of P ≥ 5% is classified as high, P = 1-4.9 as moderately high prevalence, and P < 1% as low prevalence [17].

RESULTS

Socio-demographic characteristics of pregnant women

A significant majority of the participants, totaling 440 (80.7%) women, were between 20 and 35 years, typically considered the biologically optimal age for pregnancy. Conversely, there were 67 (12.3%) women who were under 20 years old, indicating instances of adolescent pregnancies, while 38 (7%) women were above 35 years, representing cases of advanced maternal age. Regarding marital status, a substantial portion of the participants, 415 (76.1%) women, were married, whereas 130 (23.9%) were unmarried. Concerning educational attainment, it was found that 376 (69%) women had completed secondary education, followed by 89 (16.3%) women who had completed only primary education. The data on income levels reveal financial challenges these women face, with 378 (69.4%) classified as low-income earners and 160 (29.4%) identified as middle-income earners. Occupationally, the largest subgroup consisted of petty business workers, numbering 284 (52.1%), followed by homemakers at 95 (17.4%). Regarding the stages of pregnancy, 202 (37.1%) women were in their first trimester, while 277 (50.8%) women were in their second trimester, as detailed in Table 1.

Prevalence of HIV infections among pregnant women

The data presented illustrates the prevalence of HIV infections among pregnant women, with a focus on their HIV status. The results indicate that 2.4% of the sampled population is HIV positive, signifying a moderately high prevalence of the virus within this demographic. Despite this, a substantial majority, 97.6%, of the population reported being HIV-negative, highlighting that a predominant number of pregnant women do not carry the virus, as shown in the Figure.

Bivariate analysis of HIV prevalence determinants among pregnant women

In the bivariate analysis of HIV prevalence determinants among pregnant women, specific categories demonstrated the highest prevalence of HIV-positive cases: the age group of 20-35 years had 13 (2.4%) cases, while other categories had no cases; married pregnant women accounted for 11 (2.0%) cases. The secondary education group reported 8 (1.5%) cases, the low-income category noted 7 (1.3%), while the petty business occupation revealed 10 (1.8%) positive cases. Additionally, trimester one recorded 7 (1.3%), and the over-one parity group indicated 8 (1.5%) positive cases. Despite these observed variations in prevalence among the different predictor variables, the statistical analysis confirms that none of these associations are significant, as indicated by p-values (>0.05), indicating that assessed predictors do not substantially influence HIV positivity among pregnant women, as described in Table 2. Due to the lack of significant relationships identified in the bivariate analysis among all predictors, the decision was made to forego further logistic regression. This choice was influenced by unexpected values resulting from zeros and the limited number of positive cases across several categories.

Table (2):    Bivariate analysis of HIV prevalence determinants among pregnant women (N = 545)

DISCUSSION