BACKGROUND: Testing of antiphospholipid antibodies (aPLs) has attracted increasing attention for its association with thrombosis and pregnancy loss. However, few studies reported long-term monitoring outcomes of patients who experienced pregnancy loss and exhibited positivity for aPLs. OBJECTIVE: We investigated the causes of fetal death in five cases with positive aPLs and traced the patients for changes in aPLs, subsequent pregnancy outcomes, and thrombotic events. METHODS: This is a report of five typical cases from a prospective cohort study on the diagnosis of antiphospholipid syndrome (APS) in patients who were hospitalized for fetal death in Xining, China. Long-term follow-up was conducted and repeat aPL testing was recommended when the patients were confirmed or suspect APS. RESULTS: All five patients had subsequent pregnancies that resulted in term livebirths. None of the patients experienced thrombotic events. One showed progression of aPL serostatus from alone IgM of aβ2GP-1 to both IgM and IgG of aβ2GP-1, two exhibited fluctuation of aPL serostatus, and one had negative conversion, and the other one had not retested aPLs and did not receive any intervention with uneventful subsequent pregnancy. CONCLUSIONS: The aPLs of a patient with APS may develop or may disappear, so long-term monitoring cannot be discounted. Also, a woman who has experienced fetal death and exhibits positivity for aPLs may not necessarily be a patient with APS, as there are a variety of conditions in which aPLs appear.