It is normal and stress does not cause miscarriage. Talk through your fears with a midwife or doctor. There is nothing you can do to protect this baby except try to look after yourself with a reasonable diet and I find a bit of exercise is a good distraction. Hormones can make us feel depressed too. Hope you find some good coping mechanisms soon. Good luck
Yes it's totally normal to worried, especially with your 1st child. I'm 30 weeks & getting more nervous the further we go, but one thing that has really helped was taking a birthing class. My husband & I enrolled at 21 week. We learned so much & it really helped take away a lot of our fears.
Making a human is not easy & giving birth is scary, but our bodies are built for this & we actually know more instinctually than we give ourselves credit for. :)
I wish you all the best.
Stress which can cause A miscarriage its normal to worry but try yur best not to do things to get ur mind off it