How common are subchorionic hemorrhages in pregnancies?

I don't know exactly how common they are but from what I've read previously, they occur in roughly 40% of pregnancies. It's not something that will necessarily occur in a subsequent pregnancy if a woman had one previously but it's best to mention to your doctor that you've been diagnosed with one in the past (if it's not the same doctor). I was diagnosed with a subchorionic hemorrhage at 7w3d after having some bleeding at 5 weeks. It's since resolved itself and I had no further bleeding and the doctor said it shouldn't put any risk on future pregnancies. Good luck and congrats on your newest addition!!