Firstly: Defining Postnatal Bleeding
Nifas linguistically: comes from nafs. From the meanings of the word nafs is blood, and the woman with postnatal bleeding is referred to as nufasa' due to this, because her blood pours forth. Or due to the fact that the great ordeal of childbirth has been concluded successfully, in which case she has experienced tanfis from difficulty – relief.
Nifas technically: is blood which outpours from the womb to childbirth or its nearness.
Secondly: Blood that Exits with Contractions Before Birth
Blood which exits before birth with contractions is considered postnatal blood. This is the position of the Hanbalis, a position among the Malikis, a position among Shafi`is, and the position of Ishaq ibn Rahawayh. It is also the choice of Ibn Taymiyyah, Ibn Baz, and Ibn `Uthaymin.
Thirdly: Blood That Exits with the New-born
Blood which exits with the new-born is considered postnatal blood. This is the position of the Malikis, Hanbalis, a position among Shafi`is, and the position of some Hanafis. It is also the choice of Ibn Taymiyyah and Ibn `Uthaymin.
Fourthly: Blood That Exits After Birth
Blood which exits after birth is the postnatal bleeding. Consensus has been quoted on this by: Ibn Hazm, al-Nawawi, and al-Rafi`i.
Fifthly: The Start of Postnatal Bleeding from Twins and Its End
Scholars have differed over the start of postnatal bleeding for twins and its end according to many views, the strongest of which are two:
The first: is that if a woman gives birth to twins, then the start of postnatal bleeding and its end is from the firstborn. This is the position of the majority: Hanafis, Malikis,  Malikis excepted one scenario, that if the first twin is born sixty days before the second, then each twin has his own independent postnatal bleeding. Hanbalis, and a position among Shafi`is.
The second: is that the postnatal bleeding starts with the firstborn and ends with the second. This is the position among Malikis, a narration from Ahmad, and the choice of Ibn `Uthaymin.
Sixthly: The Longest and Shortest Possible Durations of Postnatal Bleeding The longest possible duration of postnatal bleeding
The longest possible duration for postnatal bleeding is forty days. This is the position of the Hanafis and Hanbalis. It is also the choice of Ibn `Abd al-Barr, al-Shawkani leant towards it, and it is the verdict of the Permanent Committee. It is the position of the majority of scholars, and consensus among the Companions – Allah be pleased with them – over this has been quoted by: al-Tirmidhi and Ibn `Abd al-Barr. The shortest possible duration of postnatal bleeding
There is no specified shortest possible duration for postnatal bleeding, and this is by agreement of the four schools of jurisprudence as well as the choice of Ibn Hazm al-Zahiri.
Seventhly: Rulings Related to Postnatal Bleeding
If a woman goes through postnatal bleeding then she has all the same rulings as that for menstruation. Whatever is haram for the menstruating woman is imopermissible for the one with postnatal bleeding; so she does not pray nor fast, nor does she circumambulate the Ka`bah, nor is intercourse permissible with her, and she must wash once she has stopped bleeding, and make up fats but not prayers. Consensus has been quoted over this by: Ibn Jarir al-Tabari, Ibn Hazm in all other than circumambulation, Ibn Rushd, Ibn Qudamah, and al-Shawkani.