Praise be to Allah.
It is permissible for the man and woman to use means of contraception for a period of six months and the like for this purpose, which is to be able to do Hajj, because it is permissible to delay having children for a reason that the spouses think is in their interests.
In a statement of the Islamic Fiqh Council it says:
After examining the research presented by its members and experts on the topic of family planning, and listening to the discussions that took place on this topic;
And based on the fact that one of the aims of marriage according to Islamic sharee‘ah is to have children and perpetuate mankind, and that it is not permissible go against this aim, because doing so is contrary to the shar‘i texts and their teachings that call for having many offspring and maintaining this principle, because maintaining the principle of perpetuating the ummah is one of the five essentials which are protected by sharee‘ah,
the Islamic Fiqh Council has determined the following:
Firstly: it is not permissible to issue a general law restricting the freedom of the spouses to have children.
Secondly: it is haraam to remove the ability to have children for the man or the woman, which is known as sterilisation, so long as there is no case of necessity which dictates that, on the basis of shar‘i principles.
Thirdly: it is permissible to temporarily stop having children, with the aim of spacing pregnancies or stopping them for a specific length of time, if there is a legitimate shar‘i need for that, according to the view of both spouses with mutual consultation and agreement, on condition that this will not lead to any harm and that means used are Islamically acceptable, and that this will not cause any harm to an existing pregnancy.
End quote from Majallat Majma‘ al-Fiqh, issue no. 5, vol. 1, p. 748.
And Allah knows best.