Does not the condition for an embryo to inherit, which requires its presence in its mother's womb at the time of the testator's death, and the determination of the period of gestation in the womb as two years (according to the Hanafi school) or four years (according to the Shafi'i and Maliki schools), contradict the waiting period (iddah) of a widow, which is four months and ten days, and the possibility of her immediate marriage and conception thereafter?

There is no contradiction between specifying the 'iddah (waiting period) as four months and ten days for a widow whose husband has died, and the longer waiting period for a woman who suspects pregnancy (al-murtabah). A pregnant widow whose husband has died waits until she gives birth, while a non-pregnant widow waits four months and ten days. However, a woman who suspects pregnancy waits the maximum duration of a pregnancy, which is four years according to most scholars. If the suspicion is removed after this period, she becomes lawful for marriage. If a woman marries after her 'iddah has expired and then gives birth, if the birth occurs six months or more after her marriage, the child is attributed to the second husband. If it occurs less than six months and the child is fully formed, it is attributed to the first husband, unless he denies paternity through li'an (oath of condemnation). Her acknowledgment of the 'iddah's expiry is not considered valid.