Can Rovamycine weaken the baby's movements?

As I understand it, you mean the palpable movements of the unborn child. Rovamycin (the drug contains the antibiotic spiramycin) can be used during pregnancy if there are specific indications for this. It is believed that spiramycin does not adversely affect the fetus and is safe for the baby, and thus - it should be expected that it will not affect the parameters of fetal well-being such as movements. If you are counting fetal movements (e.g. the Cardiff method on a special card) and you have observed a significant change in the baby's activity - for example, the movements have become much weaker, then you should contact the obstetrician. I enclose additional material that may be of interest to you: https://www.gdziepolek.pl/artykuly/jakie-leki-mozna-stosowac-w-ciazy