Overall, although Uganda had a significant increase in the proportion of women who came to first ANC visit with known current HIV status during 2012–2016, this increase was small. There was also regional variation in trends of women coming with known HIV status at first ANC visit. The proportion of women who came to first ANC visit with known HIV status was low over the years of study, with fewer than 10% of women knowing their current status nationally. The proportion of known HIV positive status at first ANC visit is slightly higher than that of women that were newly tested HIV positive at first ANC visit in 2015 and 2016 nationally.
Although we found low proportions that came for the first antenatal visit knowing their HIV status over the years, national surveys show that more than half of Ugandans have been tested for HIV at some point in the past. The 2011 Uganda AIDS Indicator Survey showed that 83% of women and 70% of men had ever been tested and had received results of their last test , and information from the National HIV Testing Services showed that 42–51% of the population aged 15–49 years knew their HIV status in 2016, and that about 60% of these were women .
The overt difference in proportions of known HIV status found in this study compared to the national surveys were most likely due to the stringent measure of the known HIV negative status at first ANC visit which skewed the overall proportions of women that came with known HIV status at first ANC visit towards the unknown. In Uganda, one is considered to be known HIV negative at first ANC visit when the documented test was done within 4 weeks of the visit . However, the stringent measure is aimed at early identification of all the HIV positive women so as to implement timely PMTCT interventions. Thus it is possible that more than 5–10% of the women attending first ANC visit knew their HIV status, but either did the test outside the required window of time or attended first ANC visit without any document verifying their status, and so were considered to be of unknown HIV status.
On a positive note, the proportion of known HIV positive status at first ANC visit was slightly higher than that of women that were newly tested HIV positive at first ANC visit in 2015 and 2016. This could be due to the nationwide progress towards achieving UNAIDS first 90 which is 90% of the HIV-positive persons in a given population knowing their HIV- positive status (14). In Uganda, between July 2015 and June 2016, 69% of persons living with HIV (PLHIV) knew their (HIV-positive) status  and this had increased to 73% between July 2016 and June 2017 . Thus, the nationwide progress of the first 90 possibly also included the women of reproductive age.
The yield of those newly testing HIV positive at first ANC visit was less than that observed in the general population of 3.5% . The yield ascertained in this study could be even further lower considering that some known HIV positive women may choose to present at first ANC visit as unknown status for a number of reasons including denial. This could be mitigated by HIV recency testing. Unfortunately, we did not have any sense of recent infections because at the time of the study, recency testing was in its pilot stages in Uganda.
The HIV positive yield obtained in this study being lower than the general population yield contradicts evidence that a big proportion of new HIV infections in Uganda are among women of reproductive age . On a positive note, this could be due to the effective combination prevention efforts that have been made countrywide to reduce incident HIV cases. It could also be possible that the PMTCT program has been successful with many positive women being diagnosed through the program during previous pregnancies as well as other avenues. However, it can be due to the fact that some women do not attend ANC and thus may miss HIV testing. This calls for innovative measures to identify the ‘hidden’ new HIV positive individuals especially women of reproductive age if we are to achieve elimination of mother-to-child transmission of HIV (EMTCT).
The variations in trends in proportions of women that come with a known current HIV status at first ANC visit regionally may be attributed to the differences in the HIV prevalence in the different regions. The 2016 Uganda Population-based HIV Impact Assessment puts the highest prevalence at 7.7% in South Western region, 6.6% in Kampala and the lowest at 2.8% in West-Nile . This regional variation of prevalence is similar to the one of the 2011 Uganda AIDS Indicator Survey . The fact that the more highly-prevalent regions also had higher proportions of women attending first ANC visit with known current HIV status could be because HIV testing campaigns and services are more emphasized in these regions. Higher prevalence regions potentially have higher HIV positive yields  which in turn gives better return on investment in HIV testing. As such, more proportions of people in these regions are tested since they are perceived to be at greater risk of HIV than their counterparts in the low prevalence regions. Thus areas of low HIV prevalence such as the West Nile had more stagnating or declining trends of people that came with known HIV status at first ANC visit.
Limitations and strengths
Our findings should be interpreted with the following limitations. We used DHIS2 data which is aggregate data and so we could not look out for individual effects such as repeat pregnancies in the same woman during the study period. Also, some variables were new and could not be assessed over the whole study period. Relatedly, the new variables (data elements) are initially not very accurate because the health workers that often double as data entrants take some time getting accustomed to looking out for and reporting them.
Our estimate of the proportion of women who knew their current HIV status at first ANC visit was likely an underestimate due to the documentation required to determine a known HIV status at first ANC visit. However, the underestimation was most likely skewed to the HIV negative women who had to have had a test within 4 weeks. The HIV positive women are less likely to be underestimated because they are more likely to report for ANC with their HIV care card.
Our analysis was only a bivariate trend. The effect of other characteristics that could have been considered in the final model such as the woman’s parity and age or whether she was a rural or urban dweller could not be assessed. This is because the data we used was aggregate and so could not account for individual characteristics. Other covariates such as government spending and donor funding would have been important to analyze, however, the donor funding by region differs from the national programming HIV regions considered in this analysis.
In addition, ANC data in DHIS2 have potential selection biases such as: distribution of public and private ANC services, misrepresentation since not all women attend ANC in DHIS2 reporting facilities and a small proportion opts not to attend professional ANC at all [23,24,25]. Nevertheless, a large proportion of Uganda’s population attends public health facilities  and so the results can be generalized to the entire country.
Finally in countries with a mature and generalized HIV epidemic such as Uganda, ANC indicators are important sources of data in HIV surveillance and provide good data on epidemic trends over time [23,24,25]. Our findings therefore can be used as proxy indicator of adult Ugandan women’s seeking behavior to know their HIV status, thus reflecting the national and sub-national trends of women of reproductive age who know their HIV-positive status in Uganda.