Pregnancy and classes

This week I am studying. From Sunday until Monday, I am taking a class.
I registered in August, before knowing I will be pregnant by now. I don't think knowing would have changed my choice of taking the class. The only thing that surprised me is that the class is around 150 km away from home (approximately 2 hours by train), in a beautiful mountain resort. I'm not happy to be away from my family, but it is a welcome pause from my daily routine. I miss going to gym the most (my husband would loooove to hear this).
What I discovered about my new pregnant self is that I find it very tiring to be here and to pay attention to class 8 hours per day, every day, including Saturday and Sunday! Am I getting too old for learning in an academic environment? Or is it the pregnancy that gets in the way? I hope it's the latter! And I hope I will go back to being my normal, attentive and active self soon after the birth of my baby.