Tateishi A, et al. - During this study, experts contemplated the frequency of histopathological changes of placental tissue in the subgroups of pregnancy-induced hypertension (PIH), such as mild and severe PIH and early-onset (< 34 weeks) and late-onset (≥ 34 weeks) PIH. When compared to late-onset PIH, the early-onset PIH illustrated histopathological changes of placental tissue consistent with the two-stage disorder theory more frequently. Hence, it was inferred that early-onset PIH and late-onset PIH served as distinct entities or different extremes of the PIH spectrum.