Contribution of Syphilis to Adverse Pregnancy Outcomes in People Living With and Without HIV in South Brazil: 2008 to 2018

Abstract

Background Syphilis coinfection among pregnant people living with HIV (PLH) may worsen pregnancy outcomes. We evaluated the impact of syphilis coinfection on pregnancies in south Brazil. Methods Data were extracted from hospital records between January 1, 2008, and December 31, 2018. Preterm birth (PTB), low birth weight (LBW <2500 g), and a composite adverse infant outcome (AIO: HIV vertical transmission, loss to follow-up before HIV diagnosis, stillbirth, congenital syphilis) were evaluated among pregnancies without HIV and syphilis (PWOH + S), PLH monoinfection, syphilis monoinfection (PLS), and PLH with syphilis (PLH + S). Results Among 48,685 deliveries where patients were tested for HIV and syphilis, 1353 (2.8%) occurred in PLH; of these, 181 (13.4%) were HIV/syphilis coinfected (PLH + S). Among PLH, 2.4% of infants acquired HIV and 13.1% were lost to follow-up before HIV diagnosis. Among all PLS, 70.5% of infants acquired congenital syphilis. Across the cohort, 1.2% stillbirths/neonatal deaths occurred. Thirty-seven percent of PLH + S did not initiate antiretroviral therapy versus 15.4% of PLH monoinfection (P < 0.001). Less than half (37.6%) of PLH + S had VDRL titers ≥1:16 compared with 21.7% of PLS only (P < 0.001). Among PLH, syphilis coinfection and unknown/high VDRL titers (≥1:16) increased AIO risk more (adjusted relative risk [aRR], 3.96; 95% confidence interval [CI], 3.33–4.70) compared with low VDRL titers (≤1:8; aRR, 3.51; 95% CI, 2.90–4.25). Unsuppressed viremia (≥50 copies/mL) was associated with risk of PTB (aRR, 1.43; 95% CI, 1.07–1.92) and AIO (aRR, 1.38; 95% CI, 1.11–1.70) but not LBW. Lack of prenatal care was significant in predicting PTB and LBW in all PLH and PLS monoinfection. Conclusions Syphilis coinfection worsens AIOs in all women and compounds negative effects of HIV infection during pregnancy. Effective syphilis treatment and HIV viral load suppression are paramount for optimal obstetric care.