Yes, it's actually quite normal for people to hold their breath during deep meditative states, like Trance Meditation. It's just a part of your body adapting to the meditative state and finding its own rhythm.
As you enter a meditative state, especially when you're focusing on something like "going down the ladder" in your Trance Meditation, your attention becomes deeply absorbed in the mental process. This intense concentration can sometimes cause your body to temporarily "forget" to breathe, which leads to the natural tendency to hold your breath without realizing it. It's similar to how you might hold your breath while focusing intently on something, like solving a problem or concentrating on a difficult task.
As you move deeper into a trance or meditative state, your body enters a deeply relaxed state. In deep relaxation, breathing can naturally slow down. Sometimes, this slows down so much that your breath might stop temporarily without conscious intention. This is part of the body's natural response to the deeply calm and still state you're achieving.
The autonomic nervous system controls involuntary bodily functions, including breathing. During deep meditation, particularly in altered states like Trance Meditation, the nervous system may go into a more parasympathetic (rest and digest) mode, which can sometimes involve very slow, shallow, or even momentary cessation of breathing. This can feel like you're holding your breath, even though it's simply your body responding to the deep meditative state.
It is nothing to worry about.