Introduction:
Antiphospholipid syndrome is a clinical autoimmune syndrome characterized by arterial or venous thrombosis and pregnancy pathology such as fetal loss after 10 weeks of gestation, recurrent miscarriage or intrauterine growth restriction.

Material and Methods:
This study describes a case of preeclampsia in a 37-year-old primiparous woman at 30 weeks' gestation with no previous thrombotic history.

Results:
The stillbirth and findings of placental thrombosis raised the suspicion of antiphospholipid syndrome, which was confirmed by the finding of antibodies in the mother's blood. The diagnosis and treatment are described below. In our case, placental tissue sections were stained and observed. Various placental changes were detected with the presence of placental intravascular thrombi. The most important finding of this case study was the presence of severe preeclampsia in the setting of antiphospholipid syndrome, with no previous medical history.

Conclusions:
In conclusion, antiphospholipid syndrome can be directly related to preeclampsia during pregnancy and can lead to complications that can be prevented if there is immediate medical intervention.