Fathwa, - Using birth control

Question
I know a girl who wants to get married but she wants to finish her
university so she doesn't want children until she finishes university
is it allowed to use condom or pills to avoid having children?
Answer
All perfect praise be to Allaah, The Lord of the Worlds. I testify
that there is none worthy of worship except Allaah, and that
Muhammadis His slave and Messenger.
There is no harm in delaying pregnancy in order to achieve a
permissible benefit as Allaah permitted it for a need.
ImaamMuslimreported that a man came to the Prophetand told him: 'I
have a slave girl who is our servant and I have intercourse with her,
but I do not wish that she becomes pregnant.'So the
Prophetremarked:"You can practice coitus interruption if you so wish."
There are many means for preventing pregnancy, and they differ based
on the physical harm that they might cause, or the violation of
religious limits they include or may lead to, so one has to use the
easiest means. The harm is defined by doctors who specialize in this
field.
The spouses are advised to practice natural planning as one of the
beneficial methods, which is avoiding sexual intercourse when the egg
is ready to be fertilized; the egg is at this stage at regular times,
so one can know this by asking doctors.
Finally, the following matters should be noted:
1( One of the objectives of the Islamic Law in marriage is to have
children, so whenever a Muslim can achieve this objective, he should
not delay it.
2( The study of the woman should meet the religious requirements, for
instance the field of her studies should be in accordance with her
nature. Besides, she should abide by Hijaab when going out, avoid
forbidden mixing of men and women and so forth.
Allaah knows best.