Table 2. Influence of being older than 18 years at parturition and being born before 1984 on hepatitis B surface antigen carriage by pregnant women, Hong Kong Special Administrative Region, China, 1998–2011.
| Women’s year of birth | Prevalence of HBsAg carriage (%) |
Likelihood of HBsAg carriage by a woman aged < 18 years at parturition, OR (95% CI) | ||
|---|---|---|---|---|
| All women | Women aged < 18 years at parturition | Women aged ≥ 18 years at parturition | ||
| All | NA | 2.5 | 7.7 | 0.311 (0.160–0.604) |
| ≥ 1984 | 5.8 | 1.2 | 6.2 | 0.191 (0.061–0.600) |
| < 1984 | 8.4 | 5.2 | 8.4 | 0.600 (0.262–1.370) |
| OR (95% CI)a | 0.679 (0.578–0.797) | 0.227 (0.056–0.925) | 0.714 (0.607–0.840) | NA |
CI: confidence interval; HBsAg: hepatitis B surface antigen; NA: not applicable; OR: odds ratio.
a Likelihood of hepatitis B surface antigen carriage by a woman born in or after 1984, when neonatal vaccination against the hepatitis B virus became available.