Yes! And especially that her friend is pregnant now... I am surprised there was no warning about jasmine tea! I love jasmine tea, it is great for depression and relieving stress but it is really bad for pregnant women. It may cause miscarriage.
I think she does know, again because she already talk to her friend about it when she learned that she( the friend)was pregnant. So I think the ducess knows. The problem is not the tea it's her health/the weak body she was reincarnated in.
There are herbs that will make us women be infertile. I love tea, i will drink 2 cups in one sitting, but i only recently found out that some in my tea collection is not really good for my womanhood. Tho, i have no desire to have children, but it was the doctor's job to let me know the complications... In the story they only talked about the caffeine in black tea which is a common knowledge... But you know this is webtoon and it is fantasy... But i love tea so much that i do not want people having bad experience.
but she might not be getting pregnant because of some teas that she may be drinking? Idk if she truly knows every single effect every tea has in the world, but I know that many are used to clear the womb, like hibiscus, a personal favourite