Baby aspirin during pregnancy ?

Hi, welcome to the ehealth forum and I am glad to help you.
You seem concerned by the history of one miscarriage and borderline anticardiolipin antibodies with diagnosis of Lupus and positive anti-Ro and anti-La antibodies. You are unsure about whether to start aspirin + heparin which is known to reduce the risk of miscarriage.
You seem to have been suggested the diagnosis of secondary antiphospholipid syndrome(APS) which has a risk of recurrent miscarriages. The reason for this is unclear; some researchers believe that antiphospholipid syndrome causes tiny blood clots to block the blood supply to the placenta. Others believe that having antiphospholipid syndrome may interfere with the fertilized egg’s ability to implant in the lining of the uterus. Most people who have antiphospholipid antibodies have no symptoms, though the disorder can cause blood clots and other health problems in some people. For women, recurrent miscarriages may be the only symptom of the disorder. Generally, when considering antiphospholipid syndrome as a possible factor in recurrent miscarriages, doctors look for a person to be positive for lupus anticoagulant antibodies or anticardiolipin antibodies on more than one occasion before making a diagnosis. In your case if the diagnosis is being considered fresh, repeat test can be done for anticardiolipin antibodies to confirm the diagnosis. But it seems that you have a strong case to start the therapy( low-dose aspirin and/or heparin injections) because of past history of miscarriage though you are not having any flare up of lupus. Although this treatment improves pregnancy outcomes for women with antiphospholipid syndrome, these therapies can increase the rates of third-trimester pregnancy complications, however, so women with antiphospholipid syndrome usually need to see a high-risk specialist and have regular prenatal care during pregnancy. Low molecular weight heparin is quite safe in pregnancy with few side effects and it does not cross the placenta. The risk of abruptio placentae is there with aspirin and dose related and rarely seen with baby aspirin so low dose aspirin is relatively safe in pregnancy.
Hope this helps. Take care.
Note: This post is not to emphasise final diagnosis as the same cannot be made online and is aimed just to provide medical information and no treatment suggested above be taken without face to face consultation with health care professional.