Female guardsmen are absolutely not a normal part of the setting. They didn't even have miniatures till last year. In imperial guard fleets the women are too busy having and raising babies to fight on the front line. This was a core part of the imperial guard lore as casualties are high for them and this was a major way in which they replenished their numbers. Females being just as numerous as men in the guard is a new woke retcon from games workshop.