Is limiting the number of children without using invasive contraception permissible?
Limiting the number of children is not permissible except for a valid reason as health problems during pregnancy.
Regulating and organizing pregnancy is permissible, for example by making it every 2 years so that a woman can breastfeed her baby and take a rest. As for limiting children or preventing pregnancy without any reason, this is not permissible, even if it was by the means of isolating (without taking invasive contraception).
Shaikh Hassan Al Banna was asked by a lady regarding limitation of children without using invasive contraception and he replied by telling her:
“Do not be afraid from Allah’s destiny, and from what Allah decrees on you” meaning: Do not worry about being pregnant, leave it to Allah, and accept whatever Allah decrees.