Honestly, at 1 month go for it if you have the energy, because by the 3rd trimester you will be too tired and heavy to even think about it, haha! It's generally safe as long as your doctor hasn't put you on pelvic rest.
Since it is just the first month and the pregnancy is very delicate, I would suggest being extremely cautious. If you have any history of spotting or cramping, it's best to avoid it completely until you cross the first trimester and consult your doctor.
I know how every little thing can make you feel anxious in these early weeks. If your pregnancy is low-risk, it is safe, but please don't do anything that makes you lose your peace of mind. Your emotional comfort is very important right now.
Medically, orgasms don't cause miscarriage in low-risk pregnancies because the baby is safely cushioned. However, if you've had IVF, spotting, or previous complications, doctors usually advise pelvic rest in the first trimester. Best to get a quick confirmation from your gynac during your first scan.
If you are feeling up to it and not throwing up your guts like I was, it's completely normal. The mild uterine contractions from an orgasm are harmless for a normal pregnancy, but if you feel any cramping after, just lie down and rest.
