Sexually transmitted infections in pregnancy: Is there evidence to support diagnostic testing of curable STIs in routine antenatal care in South Africa?

Nyemba, Dorothy

Sexually transmitted infections in pregnancy: Is there evidence to support diagnostic testing of curable STIs in routine antenatal care in South Africa?

Thesis / Dissertation

2026

Publisher

University of Cape Town

Department

Department of Public Health and Family Medicine

Faculty

Faculty of Health Sciences

Abstract

Background The burden of sexually transmitted infections (STIs), specifically curable infections such as Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and Trichomonas vaginalis (TV) remains high in pregnant women in most low-middle-income countries including South Africa. Curable STIs in pregnant women have been associated with several adverse pregnancy and birth outcomes such as miscarriage, stillbirth, preterm birth, low birthweight and several secondary life-threatening conditions in surviving neonates. The standard of care for STIs in antenatal care in South Africa is syndromic management and it has its known and well documented limitations. The aim of this thesis is to estimate the prevalence and incidence of curable STIs among pregnant women in South Africa. Additionally, the thesis aim is to investigate the effect of STIs during pregnancy on pregnancy and birth outcomes including vertical HIV transmission. Methods In this thesis, a systematic and meta-analytical approach was employed to assess prevalence estimates of diagnosed treatable STIs among pregnant women in sub-Saharan Africa. The analysis was conducted using studies that estimated prevalence of curable STIs among pregnant women screened using diagnostic tests. The subsequent analyses were carried out utilizing a combination of prospectively collected data from three separate cohort studies. The prospective cohorts included women living with HIV and women without HIV who received screening and treatment of curable STIs during pregnancy using diagnostic tests. Data were obtained from questionnaires (including demographics, sexual behaviour and medical history) and pregnancy and birth outcomes were abstracted from medical records. Associations were explored between positive diagnosis with a curable STI and time to treatment of infection and pregnancy and birth outcomes. Lastly, modelling the potential benefits of point-of-care testing and treatment for curable STIs during pregnancy was conducted in comparison to syndromic STI management. Results This research, using data from various sources, consistently found a high prevalence of curable STIs among pregnant women. The systematic review and meta-analysis estimated a prevalence ranging from 3% for syphilis to 14% for TV. Analyses of observational data revealed even higher prevalence of any STI (CT, NG or TV) of 40% among women living with HIV and 27% among women without HIV. In the cohort studies, prevalence of adverse pregnancy outcome (at least one of miscarriage, stillbirth, preterm birth, early neonatal death, and low birthweight) was 24%. Overall, any STI diagnosis and treatment at first antenatal clinic visit was not associated with adverse pregnancy outcome. However, an association was observed between positive diagnosis with CT or NG at first antenatal clinic visit in women living with HIV and adverse pregnancy outcome. STI positive diagnosis and time to treatment during pregnancy was not associated with adverse pregnancy outcome. Subgroup analysis showed that women who had a positive diagnosis with CT or NG infections at first antenatal clinic visit without receiving treatment during pregnancy had a four-fold increased odds of experiencing a pregnancy loss (miscarriage or stillbirth) compared to women without any STI at study enrolment. This significant difference persisted even when the analysis was restricted to women who were diagnosed with CT or NG infections at first antenatal clinic visit without receiving treatment during pregnancy compared to those who received immediate treatment. Finally, modelling the implementation of point-of-care screening and treatment of curable STIs with diagnostic tests in antenatal care compared to syndromic management showed a moderate reduction in adverse pregnancy outcomes and vertical transmission of HIV. The implementation of point of care screening and treatment of curable STIs is estimated to reduce the incidence of stillbirths by 10.1% (95%CI: 1.3 – 18.7%), preterm birth by 6.3% (95% CI:3.4 – 9.7%), small for gestational age by 2.7% (95% CI: 0.7 – 4.9%), low birth weight by 9.1% (95% CI: 0.9 – 18%). Additionally, screening and treatment of curable STIs during pregnancy with diagnostic tests is anticipated to reduce antenatal maternal HIV incidence by 10.0% (95% CI: 1.0-20.1%) and an 8.6% (95% CI: 5.2-13.8%) decrease in the vertical transmission of HIV. Conclusion This thesis has highlighted the significant burden of curable STIs among pregnant women in South Africa, particularly among women living with HIV. The current standard of care, syndromic management, fails to detect numerous asymptomatic infections during pregnancy. While this research found no association between treated STIs at the first antenatal care visit or time to treatment and overall adverse pregnancy outcomes, it did reveal an increased risk of pregnancy loss (miscarriage and stillbirth) among women with untreated STIs. Our findings suggest that the introduction of point-of-care screening and treatment of curable STIs in antenatal care has potential to reduce adverse pregnancy outcomes including maternal HIV incidence and vertical transmission of HIV. This research demonstrates the need for enhanced STI management and the need for further research to evaluate the intervention that incorporates aetiological screening and treatment of curable STIs antenatal care settings and move beyond syndromic management.

Keywords

STI

pregnancy

Reference:

Collections

PhD / Doctoral

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