If it’s a regular sewing machine and not one of those industrial ones then you should be fine.
It’s just like using any other electric appliance – if it’s not making strange noises or smelling funny then it should be fine.
However I would recommend taking a break during your period. The last thing you need is extra fatigue from using the machine AND from your period.
Why not use that time to take a relaxing bath instead?
Does Using A Sewing Machine Affect Periods?
In general no.
There is no definitive scientific evidence linking the use of sewing machines and other forms of needlework to changes in menstrual cycles.
However some individual women may notice that their periods become irregular or even stop completely when they start using a sewing machine on a regular basis.
This is most likely due to the stress of learning a new skill and the physical exertion involved in using a sewing machine both of which can affect hormone levels and cause period changes.
If you notice any changes in your period after starting to use a sewing machine it’s best to consult with your doctor to rule out any underlying medical conditions.