The study took place at the Centre Hospitalier Universitaire d’Abéché, Centre Hospitalier Universitaire de la Mère et de l’Enfant, Centre Polyvalent Alnadjma.

Our study lasted 18 months, from June 2021 to December 2022.

We conducted a prospective, descriptive, cross-sectional and analytical study of pregnant women on ARVs.

For this study, 183 HIV-1-positive pregnant women on ARVs were followed from pregnancy to delivery. All these women followed the PMTCT protocol and antenatal consultation (ANC).

HIV-1-positive mothers who had given their consent were included in this study.

HIV-2 positive women and non-consenting women were not included in this study.

We had obtained clearance from the French National Committee on Ethics in Human Health Research, giving approval to carry out the study. In addition, the research sites had given their own authorization for the study.

Finally, each participant gave informed consent to be included in the study. Confidentiality was ensured by coding the data collection forms.

The biological material used in this study was blood collected in an EDTA tube for quantitative PCR/RT.

Assessment of viral load in pregnant women on ARVs was carried out using the HIV-1 expert gene device and the biocentric system according to protocol.

The TCD4 lymphocyte count was then assessed using the BD presta device, according to the same protocol.

Data were recorded on an Excel 2013 workbook and processed using SPSS Version 25.0 software.

Age distribution

Analysis of the age distribution of HIV-1-positive mothers on ARVs reveals distinct trends between the cities of N’Djamena and Abéché.

In N’Djamena, the most represented age group is 15 - 25 years, with 61% (83/136) of women, and an average age of 24.2 ± 5.39 years ( Table 1 ). In Abéché, on the other hand, the average age of mothers is slightly higher, at 25.89 with a standard deviation of 5.93, with women aged 26 - 35 being the most represented (49.1%) ( Table 1 ). These results are comparable to those obtained in other studies carried out in sub-Saharan Africa. For example, DAKE’s study found that the age group [36 - 45] was in the majority, with 32.80% [10] . This confirms that HIV affects the most active population of which our age group is a part.

This predominance of young women can be explained by the fact that this age group corresponds to a period of maximum sexual activity, thus increasing the risk of transmission of sexually transmitted infections, including HIV.

Educational level

Our study revealed that the majority of HIV-1 positive mothers are in school, with 86.3% in N’Djamena and 82.5% in Abéché ( Table 1 ). This high proportion of women attending school could be linked to greater awareness and knowledge of HIV/AIDS and the risks of mother-to-child transmission. Indeed, better-informed women are more likely to undergo screening and treatment during pregnancy. Education plays a crucial role in acceptance and adherence to PMTCT programs. A higher level of education is associated with a better understanding of the risks and benefits of treatment, leading to better compliance and more favorable outcomes, and facilitating communication and understanding of the care offered.

Marital status and occupation of pregnant women

In our two study sites, the majority of HIV-1 positive women were married: 69.1% in N’Djamena and 70.2% in Abéché. In addition, a significant proportion of these women were housewives: 60.3% in N’Djamena and 73.7% in Abéché ( Table 1 ). These results are comparable with those of Diop in 2021, who reported that 90.3% of the pregnant women in her study were married and 52.8% were housewives [11] . In the African context, and more particularly in Chad, it is common for women of childbearing age to be married and to devote themselves to household tasks. Married women often benefit from the support of their spouse, which can facilitate access to healthcare services and improve compliance with treatment. Our results also show a variation from other studies. For example, these results are comparable to those of BAGAYOKO [12] and SAMAKE [13] who found a percentage of 59% and 67.8% respectively among married people. Samaké (2023) found that 93.3% of the women surveyed were married and 64.4% were housewives [13] . This difference may be attributed to socio-cultural variations between different regions of Africa.

In summary, our results show that HIV-1 positive women on ARV in the cities of N’Djamena and Abéché are predominantly young, educated, married and housewives. These socio-demographic characteristics influence their access to care and adherence to ARV treatment, which is crucial to the success of PMTCT programmes.

This section concerns the distribution of TCD4+ lymphocyte levels in pregnant women on ARV in Ndjamena ( Table 2 ) and Abéché ( Table 3 ).

City of N’Djamena

At inclusion (M0), the mean CD4 cell count in pregnant women on ARV treatment in N’Djamena was 292.4 ± 19.97 cells/mm³ with 20% CD4 counts of 0 - 200 cells/mm³. This count increased significantly, reaching 699.7 ± 31.72 cells/mm³ at M6, and 956.12 ± 98.928 cells/mm³ at M12 ( Table 2 ). This progressive and significant increase (p < 0.0001) demonstrates significant immune restoration under ARV treatment. At M12, the vast majority of women (99.3%) had a TCD4 lymphocyte count greater than 500/mm³, indicating a good immune response and a reduced risk of disease progression.

City of Abéché

In Abéché, the trend was similar. At M0, 18.8% of women had a CD4 count of less than 200 cells/mm³. However, by the sixth month of treatment, 84.9% of patients had a CD4 count above 500 cells/mm³, reaching 84.9% at M9 and 960.26 ± 130.030 cells/mm³ at M12, i.e. 94.3% CD4 count above 500 cells/mm³. Comparison of CD4 counts at baseline and at M12 also showed a significant difference (P < 0.0001), indicating an improvement in the immune status of women on ARV ( Table 3 ).

Both our results are superior to those of Saka et al. (2018) in Togo, who observed less marked increases in TCD4 lymphocyte levels in pregnant women on ARVs (Sangaré, 2007) [14] . This difference could be attributed to variations in treatment protocols, patient adherence to treatment, and the quality of care available. The significant increase in TCD4 lymphocytes observed in our study indicates an effective immune response to ARV treatment, reducing the risk of opportunistic infections and improving the quality of life of HIV-positive pregnant women. These results underline the importance of regular monitoring of TCD4 levels to adjust treatment if necessary and ensure optimal outcomes for both mother and child.

Our results show a significant increase in TCD4 lymphocyte levels in pregnant women on ARV in the cities of N’Djamena and Abéché, confirming the efficacy of the treatment.

Plasma viral load is a key indicator of the efficacy of antiretroviral treatment and the risk of mother-to-child transmission of HIV. Effective antiretroviral treatment should reduce the viral load to undetectable levels, thereby minimising the risk of transmission of the virus.

City of N’Djamena

At the start of treatment (M0), 68.5% of patients had a viral load greater than 1000 copies/ml. Over the course of the study, this proportion decreased significantly. At M3, 16.9% of patients had an undetectable viral load, rising to 33.86% at M6, 91.2% at M9, and 90.8% at M12. Our result is better than that obtained by DAKE, which obtained 82.05% of patients with a CD4 count >500 cells/mm 35 [10] .

However, patients gained an average of 303.43 cells/mm³, which is in line with our results. The mean viral load fell from 17332.82 ± 72899.105 copies/ml at M0 to 68.73 ± 167.245 copies/ml at M12.

City of Abéché

In Abéché, 94.3% of patients initially had a viral load greater than 1000 copies/ml, with a mean of 4064.75 ± 9394.078 copies/ml. At M9, the mean was 875.51 ± 192.932 copies/ml, with 75.5% of patients having an undetectable viral load. At M12, the mean was 2423.79 ± 9980.594 copies/ml, with 92.8% of patients having an undetectable viral load.

Our results show improved viral suppression compared with Diallo et al. (2016) in Guinea, where 36.6% of mothers followed up had an undetectable viral load [15] .

DAKE found an undetectable viral load in 92.31% of patients started on TLD after six months of treatment [10] . This increased efficacy can be attributed to improved adherence to treatment, rigorous care management and increased support for PMTCT programmes in Chad. The results of our study show that antiretroviral therapy is effective in improving the immune profile of HIV-positive pregnant women and reducing the plasma viral load to undetectable levels. These improvements reduce the risk of mother-to-child transmission of HIV ( Table 4 , Table 5 ).

City of Abéché

In Abéché, 94.3% of patients initially had a viral load greater than 1000 copies/ml, with a mean of 4064.75 ± 9394.078 copies/ml. At M9, the mean was 875.51 ± 192.932 copies/ml, with 75.5% of patients having an undetectable viral load. At M12, the mean was 2423.79 ± 9980.594 copies/ml, with 92.8% of patients having an undetectable viral load.

Our results show improved viral suppression compared with Diallo et al. (2016) in Guinea, where 36.6% of mothers followed up had an undetectable viral load [15] . This increased efficacy can be attributed to better adherence to treatment, rigorous care management and strengthened support for PMTCT programmes in Chad.

The significant reduction in plasma viral load observed in our study testifies to the efficacy of antiretroviral therapy in reducing mother-to-child transmission of HIV. This sustained reduction in viral load is essential to prevent transmission of the virus to the newborn and to improve the health prospects of HIV-positive mothers. The efforts of the Chadian government, notably through awareness campaigns, the increase in PMTCT sites and the provision of free ARVs, have played a crucial role in improving the results of our study.

The results of our study show that antiretroviral therapy is effective in improving the immune profile of HIV-positive pregnant women and in reducing the plasma viral load to undetectable levels. These improvements reduce the risk of mother-to-child transmission of HIV. PMTCT strategies must continue to be strengthened and adapted to maintain these positive results and achieve the ultimate goal of zero vertical transmission of HIV.