In principle, application is possible. However, it is up to the client to decide whether she wants to forego treatments with chemical agents, such as head hair colouring, eyelash or brow tinting or even eyelash lifting.
The manufacturer says the following about this:
We have no information on negative effects from use during pregnancy. Please note, however, that we have not conducted any special studies with pregnant and breastfeeding women. We recommend consulting your doctor before use.