Is the Hajj valid, or must it be repeated, if clothes became impure in Mina during Hajj in the sixth month of pregnancy, and were not changed due to the difficulty of doing so, and the pilgrim sufficed with wiping them with water without being certain of complete purification?

First: Your feeling that your clothes are impure does not affect the validity of your Hajj, as the pillars of Hajj do not stipulate purity of clothing, except for what some scholars mentioned regarding Tawaf (definition), and this is specific to one who is certain of the impurity.

Second: It is not necessary to change clothes simply upon contact with impurity; removing the impurity is sufficient. One should be wary of obsessive doubts (waswas), for the default state of clothes is purity, and this default is not changed except by certainty. Based on the rule, "Certainty is not removed except by similar certainty," if you are not certain of the presence of impurity on your clothes, then your prayer and Tawaf are valid. Sheikh Al-Uthaymeen, may Allah have mercy on him, emphasized that the default state of clothes is purity, and they do not need to be washed unless you are certain that they have been affected by impurity.