He committed zina with her and she got pregnant; can he marry her while she is pregnant or should she abort he foetus?
Question

                One of my wifes divorced Muslim friends is not married and is pregnant. She wants to know if it is haraam for her to have an abortion or whether she should keep it (she is 4 weeks pregnant). The man who has made her pregnant also wants to marry her. Can she get married while she is pregnant ? There is no chance that anyone else is the father.
Praise be to Allah.
    Firstly: 

    It is permissible for the one who committed zina to marry the 
    woman with whom he committed zina if they are no longer regarded as zaani, 
    which is after repenting sincerely. If she is pregnant, it is not 
    permissible to do the marriage contract with her until her pregnancy ends, 
    and the child is not to be named after the zaani according to the majority 
    of scholars. Some scholars are of the view that the illegitimate child is to 
    be called after the zaani if he acknowledges him. See the answer to question 
    no. 33591 

    In Fataawa al-Lajnah al-Daa’imah it says: What is 
    required of both of them is to repent to Allah then to give up this crime 
    and regret what has happened in the past of committing immoral actions, and 
    they should resolve never to go back to it and they should do a lot of 
    righteous deeds in the hope that Allah will accept their repentance and turn 
    their bad deeds into good deeds. Allah, may He be exalted, says 
    (interpretation of the meaning):
“And those who invoke 
    not any other ilaah (god) along with Allaah, nor kill such person as Allaah 
    has forbidden, except for just cause, nor commit illegal sexual intercourse 
    __ and whoever does this shall receive the punishment.
69. The torment will be 
    doubled to him on the Day of Resurrection, and he will abide therein in 
    disgrace;
70. Except those who 
    repent and believe (in Islamic Monotheism), and do righteous deeds; for 
    those, Allaah will change their sins into good deeds, and Allaah is 
    Oft‑Forgiving, Most Merciful
71. And whosoever 
    repents and does righteous good deeds; then verily, he repents towards 
    Allaah with true repentance”
[al-Furqaan 25:68-71]

    If you want to marry her, you have to wait until it is 
    established that she is not pregnant by waiting for one menstrual cycle 
    before doing the marriage contract with her. If it turns out that she is 
    pregnant, it is not permissible for you to do the marriage contract with her 
    until after the pregnancy ends, in accordance with the words of the Prophet 
    (blessings and peace of Allah be upon him) that a man should not irrigate 
    the crop of another with his water.  

    End quote from Fataawa al-Lajnah al-Daa’imah, 
    Majallat al-Buhooth al-Islamiyyah, vol. 9, p. 72 

    Secondly:


    It is not permissible to abort the foetus in order to get rid of the shame 
    of zina. See the answer to question no.
    13331. 

    And Allah knows best.