Factors associated with STI incidence in pregnant women in South Africa (2016–2018)
| Any STI, n (%) | No STI, n (%) | IRR (95% CI) | |
| Total | 21 (5) | 398 (95) | |
| Sociodemographic characteristics | |||
| Maternal age (years), median (IQR) | 30 (25–33) | 30 (26–34) | 0.96 (0.89 to 0.98) |
| GA at first ANC (weeks), median (IQR) | 17 (15–26) | 18 (13–23) | 1.01 (0.95 to 1.08) |
| Education level completed | |||
| Primary | 9 (43) | 134 (34) | Ref |
| Secondary | 9 (43) | 248 (62) | 0.55 (0.22 to 1.40) |
| Tertiary (college/university) | 3 (14) | 16 (4) | 2.50 (0.68 to 9.26) |
| Relationship with father of child | |||
| Married/cohabitating | 12 (57) | 219 (55) | Ref |
| Not married/non-cohabitating | 7 (33) | 169 (42) | 1.00 (0.43 to 2.30) |
| No relationship | 2 (10) | 10 (3) | |
| Employment status | |||
| Formal employment | 8 (38) | 149 (37) | Ref |
| Informal employment | 0 (0) | 12 (3) | 0.55 (0.22 to 1.40) |
| Unemployed/attending school | 13 (62) | 237 (60) | 2.50 (0.68 to 9.26) |
| Site | |||
| Cape Town | 5 (24) | 159 (40) | Ref |
| Tshwane District | 16 (76) | 239 (60) | 2.05 (0.76 to 5.51) |
| Clinical characteristics in this pregnancy | |||
| HIV status | |||
| Positive | 17 (81) | 304 (76) | 1.29 (0.44 to 3.77) |
| Negative | 4 (19) | 94 (24) | Ref |
| Sexual behaviour during pregnancy | |||
| Vaginal sex | 17 (81) | 359 (90) | 0.48 (0.17 to 1.38) |
| Oral sex | 2 (10) | 23 (6) | 1.66 (0.41 to 6.73) |
| Anal sex | 1 (5) | 10 (3) | 1.85 (0.27 to 12.6) |
| 2+ sex partners in the past 3 months | 0 (0) | 12 (3) | |
| Suspect partner of having another sex partner | |||
| No | 7 (33) | 194 (49) | Ref |
| Yes | 8 (38) | 126 (31) | 1.71 (0.63 to 4.62) |
| Don’t know | 5 (24) | 77 (19) | 1.75 (0.57 to 5.36) |
| N/A* | 1 (5) | 1 (1) | 14.3 (2.99 to 68.8) |
| Partner’s serostatus | |||
| Concordant HIV-negative | 2 (10) | 65 (16) | Ref |
| Concordant HIV-positive | 2 (10) | 72 (18) | 0.90 (0.13 to 6.42) |
| Serodiscordant | 2 (10) | 62 (16) | 1.04 (0.14 to 7.43) |
| Serostatus unknown | 15 (70) | 199 (50) | 2.34 (0.53 to 10.26) |
Confidence intervals in bold had sufficient evidence to conclude that the groups were statistically significantly different
*Refers to women who did not have a partner; they were not in a relationship.
ANC, antenatal clinic; GA, gestational age; IRR, incidence rate ratio; n, number of participants; N/A, not applicable; ref, reference.