I agree with Jan-Marie. A few ticks is quite normal for hedgehogs, as long as the hedgehog is otherwise well. If there are a lot it is different.
I imagine the hogs in Sweden would probably give birth a bit later than the ones here, if they come out of hibernation later. Here males often come out of hibernation in early March and the females approximately a month later, with first litters born from roughly May/June. You can probably work it out roughly from when the hogs there return from hibernation. It does all depend a bit on what sort of weather there has been.