Praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Scholars of the four schools of thought are agreed that the Iddah of the woman who is pregnant ends when her pregnancy ends, because Allah Says {What means}: "And for those who are pregnant (whether they are divorced or their husbands are dead), their ‘Iddah (prescribed period) is until they lay down their burden” [Al-Talaaq 65:4]. This verse is general and doesn`t differentiate between the Iddah of the pregnant woman who is widowed or divorced. Another evidence is the following narration: Narrated Al-Miswer bin Makhrama: "Subai'a Al-Aslamiya gave birth to a child a few days after the death of her husband. She came to the Prophet and asked permission to remarry, and the Prophet (PBUH) gave her permission, and she got married." {Related by Bukhari}.
Although the majority of the companions are agreed that the Iddah of the pregnant ends when her pregnancy ends, some of them have disagreed with this. For example, Malik narrated in [Al-Muwat`a/83] from Ibn Abbas (RAA) that the Iddah of the pregnant woman is the longest of the two (End of pregnancy or four months and ten days). Also, Sa`ied Bin Mansour narrated in [Al-Sunan, vol.1/pp.396] this same view from Ali Bin Abi Talib. In other words, if her pregnancy ends after more than four months and ten days then her Iddah ends when her pregnancy ends, but if her pregnancy ends before four months and ten days then her Iddah ends after she completes four months and ten days.
Ibn Abed Al-Barr says: "It was narrated that Ibn Abbas took back this view and followed the agreement of the companions based on the above narration. This is true because Ibn Abbas`s fellow scholars, such as Ikrimah, `Ataa`, Tawoos and others, are of the view that the Iddah of the pregnant ends when her pregnancy ends based on the above narration of Subai'a Al-Aslamiya. This is also the view of all scholars from among the companions and the Tab`ieen, in addition to all the scholars of Sharia." {At-Tamheed, vol.20/pp.33}.
An-Nawawi says: "This view was adopted by the majority of the scholars from amongst the righteous predecessors and successors who said: "The Iddah of the pregnant ends when her pregnancy ends, even if she gave birth a moment before her husband`s death. Her Iddah ends before he is given the burial wash and she is allowed to remarry. This is the view of Malik, al-Shafie, Ahmad and all scholars to the exception of the narrations from Ali, Ibn abbas and Sahnoon (Maliki) who said that her Iddah is the longest of the two (End of pregnancy or four months and ten days)." {Shareh Muslim, vol.10/pp.109}.
However, the Jordanian Personal Status Law has adopted the agreement of the scholars in this regard. Article (148) states: "The Iddah of the pregnant ends when her pregnancy ends or she miscarries a foetus in which all or some human features are apparent, even if they aren`t, the woman is treated in accordance with the provisions of articles (146) and (147) of this law." And Allah the Almighty Knows Best.