The first cervical cell samples were collected from women 18 months after married or 6 months after the first delivery. After that, 3 extra annual collections were obtained. The HPV genotyping method involved HPV-type-specific E7 PCR bead-based multiplex genotyping. The multiplex HPV-type-specific E7 PCR uses HPV type-specific primers targeting the E7 region for the detection of 19 high-risk or probable high-risk HPV types (16, 18, 26, 31, 33, 35, 39, 45, 51, 52, 53, 56, 58, 59, 66, 68a, 68b, 70, 73, and 82), and two low-risk HPV types (6 and 11), with detection limits ranging from ten to 1000 copies of the viral genome.