A couple things: 1) I know of no studies investigating whether the moment of stuttering is related to sex hormone release (you mention PMS). That being said, given the gender disparity (3M:1F) there's potentially something to look for. However, given the average age of onset (3-4 years) I question how much support there would be for sex hormone contributing to stuttering. 2) Cortisol, is a hormone that is released during times of stress. It's been looked at quite frequently in stutterers. The basic findings are that people who stutter do not have higher levels of state cortisol (they aren't more stressed out in general). However, cortisol levels do increase during moments of stuttering (stuttering is stressful). None of this is remarkable or even new. We already knew this from anecdotal evidence. (but it's good to have physiological evidence). 3) Increased stress can make stuttering severity increase. For all people, stuttering and fluent, when they are under duress the likelihood of disfluency increases. You state this yourself, "I get nervous and it makes it [stuttering severity] worse." This is going to increase cortisol release, and it becomes a vicious cycle. 4) BUT! There are ways to manage stuttering (and by proxy cortisol release). Stuttering is something we do, it's not something that happens to us. A speech pathologist with experience in stuttering will be able to provide you with suggestions in how to change the way you're talking to limit the effect of stuttering. There are many different ways to acutely decrease stuttering severity. And there is not a one-size-fits all approach. So, it's really a guess and check method. I also think that working with a SLP would be good with regard to the emotionality of stuttering. Stuttering can be a traumatic experience and can leave us more reactive to our communicative environment. Some desensitization to the moment of stuttering would likely help you. 5) message me if you need additional information or need assistance finding a SLP with stuttering experience in your area. (I don't check reddit every day, so it might take me a bit to get back to you). source: stuttering PhD candidate in communication disorders with an emphasis in stuttering.