You can get aspirin pretty much anywhere from Boots to any supermarket to any pharmacy. I think our low dose in the UK is 75mg as this is all I could find myself. It works by thinning the blood to help implantation and hopefully prevent early miscarriage. Many with blood disorders are advised to take it when ttc or are prescribed other things instead or alongside low dose aspirin.
It is a NSAID, like ibuprofen, so I would think it's advisable to take it after food and those with stomach ulcers and asthma I think, should avoid it. Obviously anyone allergic should avoid it too, and if you experience any adverse reactions then stop taking it. It helps inflammation, so in theory should be helpful if there's anything like this happening. Although I think it's worth asking your doctor to perform bloods to check whether you have any clotting disorders or autoimmune problems. If anyone is already taking anything to thin the blood then they shouldn't take it unless advised to by their doctor