As for nose drops, if they reach the back of the throat and they can be tasted, then it invalidates the fast. This is because the prophet encouraged the snuffing of water unless one is fasting. Laqit ibn Saburah narrated that the Prophet (peace be upon him) said: Snuff up water freely unless you
There is some disagreement regarding the permissibility of injections. It is better to delay until after the fasting period but if it is needed then they do not invalidate the fast. This is for all types of injections, whether they are intravenous and intramuscular.
The default rule for a woman who is pregnant or breastfeeding is that she must fast. If however they fear harm for either themselves or their baby they do not need to. In fact, if it is certain that it will cause harm, then it becomes obligatory not to fast. Abdullah ibn Abbas said explaining
