Why did Islam ordain a waiting period of three menstruations for 'iddah instead of just one?

The waiting period (iddah) was legislated for great wisdoms, among them: ensuring the womb is clear, elevating the status of marriage, providing an opportunity for the divorced husband to reconcile, fulfilling the husband's right, and safeguarding the rights of the husband, wife, and child. Thus, the waiting period is not only for clearing the womb but has broader objectives than that.