Types of divorce in terms of its time are divided into Sunnah divorce and Bid`ah divorce (innovative divorce which is against the Sunnah) (1).
Sunnah divorce has two types:
The first type is: To divorce one’s wife while she does not have her period and without having sexual intercourse with her.
The second type is: To divorce her while she is pregnant then gives her respite to deliver her baby.
Both types were reported in the Hadith of Ibn `Umar (may Allah be pleased with them) on the authority of Ibn `Umar that he divorced his wife while she was in her period during the lifetime of Allah's Messenger (peace be upon him). So, `Umar ibn Al Khattab asked the Messenger of Allah (peace be upon him) about that and the Messenger of Allah (peace be upon him) said: "Command him to take her back in marriage and keep her until she is purified, and then she enters the period of menses in his (house) for the second time. And he should wait until she is purified of her menses. And then if he would decide to divorce her, he should do so when she is purified before having a sexual intercourse with her; for that was the `Iddah (the waiting period) which Allah had commanded for the divorce of women." (2)
It was reported on the authority of Salim from Ibn `Umar that he divorced his wife while she was in her period, so `Umar mentioned that to the Prophet (peace be upon him) and he said: "Command him to take her back in marriage, then divorce her when she is pure or she is pregnant." (3)
Bid`ah divorce (Innovative divorce): is the divorce in which a divorcee divorces his wife without right and it is called that name because a divorcee violates the Sunnah and the command of Allah and His Messenger.
It has two divisions:
The first type is: Innovative divorce in terms of the time, which has two types:
The first type is to divorce his wife during her afterbirth blood period.
The second type is to divorce her while she is pure without having sexual intercourse with her.
Both types are mentioned in the previous Hadith of Ibn `Umar (may Allah be pleased with them).
All scholars in all times and places have agreed that both types are prohibited.
There is a third type (4) according to the majority of scholars: The Maliki, the Shafi`i, and the Hanbaly which is to divorce her one time divorce every time her period ends, however the Hanafi scholars count this type permissible.
(1) See: Al Mabsut 6/11, Al Bahr Ar-Ra'iq 22/257 and 260/3, Al Mudawanah 2/3, Al Fawakih of Ad-Duwany 3/1004, Mughny Al Muhtaj 3/307, Al Mughny 8/234. Al Mubdi` Sharh Al Muqni` 7/239, and Majmau' Al Fatawa 33/6.
(2) Reported by Imam Muslim in the book of divorce, chapter on the prohibition of divorcing a menstruating woman without her consent, Hadith No. 3725 - 4/179.
(3) Reported by Imam Muslim in the former position 3732 - 4/181.
(4) See: Mawahib Al Jalil 5/300, Al Mudawanah 2/3, Al Istidhkar 6/203, Al Mughny 8/236, and Al `Inayah Sharh Al Hidayah 5/162.