SPONTANEOUS ABORTION; ILIAC VEIN THROMBOSIS IN THE RIGHT ADNEXA; VACCINE EXPOSURE DURING PREGNANCY; This spontaneous pregnancy report was received from literature. This report concerned a 25 year old female of an unspecified race and ethnicity. The objective of the author was to present a case Exploring Serious Adverse Events in Pregnant Women. The patient's height, and weight were not reported. The patient's past medical history included: iron deficiency anaemia, and other pre-existing medical conditions included: Patient was pregnant at the time of vaccination. It was not reported whether the patient had been pregnant before. There was no family history of blood clots or miscarriages. The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin, batch number and expiry were not reported) dose, start therapy date were not reported, 1 total was administered for covid-19 prophylaxis where patient had vaccine exposure during pregnancy. The batch number was not reported and has been requested. Age at the time of vaccination 3 decades old. No concomitant medications were reported.  On an unspecified date, five weeks into pregnancy, patient was presented with a 3-day history of increased vaginal bleeding. On further inquiry, it was revealed that 13 days ago, she had received ad26.cov2.s vaccine. Latency for increased vaginal bleeding was 10 days. Examination revealed dark-red blood in the vaginal vault and an open cervical OS. A pelvic ultrasound revealed expulsion of products of conception (spontaneous abortion) as well as an incidental finding of iliac vein thrombosis in the right adnexa. Baseline investigations (complete blood count, comprehensive metabolic profile, and coagulation testing) were normal. Initially, enoxaparin 40 mg BID (twice a day) was prescribed and she was counselled regarding bleeding side effects. Later on, a haematology consultation was done and after a detailed discussion with the patient, her medication was changed to dabigatran 150 mg BID. The patient was kept on regular follow-ups. Pregnancy resulted in spontaneous abortion. Patient was Gravida-1 and Para-0. Initial research regarding the safety of mRNA-based vaccines in pregnancy revealed 46 events of spontaneous abortions reported to the Vaccine Adverse Event Reporting System (VAERS) and 115 cases of pregnancy loss among 827 participants from the V-safe registry. Thus, similar studies for the Johnson and Johnson/Janssen (J and J/Janssen) COVID-19 vaccine have become the need of the hour. According to the CDC, more than 13 million individuals have been vaccinated with Ad26.COV2.S vaccine. Out of these, thrombosis with thrombocytopenia syndrome (TTS) has been observed at a rate of 4 per million doses. Although some researchers have debated certain risk factors such as Venous Thromboembolism amongst COVID-19 vaccines, the latest CDC guidelines recommend the use of mRNA-based vaccines over adenoviral ones. According to ACOG guidelines, mRNA-based COVID vaccines are recommended over the J and J/Janssen vaccine for pregnant and lactating women. Since pregnancy is itself a hypercoagulable state, risk-estimation of TTS in pregnancy is of great significance. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The outcome of the vaccine exposure during pregnancy, iliac vein thrombosis in the right adnexa and spontaneous abortion was not reported. This report was serious (Other Medically Important Condition).; Sender's Comments: V0:20230543815- Iliac vein thrombosis in the right adnexa. The event has a compatible/suggestive temporal relationship, and is labeled. There is no information on any other factors potentially associated with the event. Therefore, this event is considered consistent with vaccine administration.  20230543815-Spontaneous abortion. The event has a compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There is no information on any other factors potentially associated with the event. Therefore, the WHO Causality is considered indeterminate. The company causality is considered unassessable.  20230543815-Vaccine exposure during pregnancy. The event has a compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There are other factors more likely to be associated with the event. Specifically: SPECIAL SITUATIONS. Therefore, this event is considered inconsistent with vaccine administration.