SPONTANEOUS ABORTION; MATERNAL EXPOSURE DURING PREGNANCY; This solicited pregnancy report received from a patient concerned a 36 year old female of unspecified race and ethnic origin. The patient was enrolled in a non-company sponsored study. The patient's weight, height, and medical history were not reported. The patient initiated treatment with covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: Unknown and expiry: unknown) dose was not reported, 1 total administered on 24-MAY-2021 for prevention of covid-19 (covid-19 immunisation). The batch number was not reported. The Company is unable to perform follow-up to request batch/lot numbers. No concomitant medications were reported. The date of the patient's last menstrual period was 09-APR-2021 and expected delivery date was 14-JAN-2022.  On 24-MAY-2021, the patient experienced maternal exposure during pregnancy. On 28-JUN-2021, the patient experienced spontaneous abortion. Laboratory data included: Ultrasound scan (NR: not provided) Baby B was diagnosed as no longer having a heartbeat. On 28-JUN-2021, the pregnancy resulted in a spontaneous abortion. Gestational age 6 weeks and 3 days. That was twin pregnancy. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient recovered from spontaneous abortion, and maternal exposure during pregnancy on 28-JUN-2021. The reporter considered the causality between covid-19 vaccine ad26.cov2.s, and spontaneous abortion, and maternal exposure during pregnancy as related. Company causality between covid-19 vaccine ad26.cov2.s, and spontaneous abortion, and maternal exposure during pregnancy was not related.  This report was serious (Other Medically Important Condition). This parent/child case is linked to 20210803924.  This case was reassessed as serious based on additional information received from patient on 30-JUL-2021, the following information was updated and incorporated into case narrative: Pregnancy (Gestation Period changed from 4 weeks to 6 weeks, outcome updated from ongoing/continuing to spontaneous abortion, EOP date, Expected Delivery Date); Event (spontaneous abortion), upgraded the seriousness of event maternal exposure during pregnancy, outcome of maternal exposure during pregnancy changed from unknown to recovered, lab (Ultrasound scan), Product (Indication changed from prophylactic vaccination to Prevention of Covid-19 (Covid-19 immunisation).; Sender's Comments: V1: Follow up information received to previous non serious case updates, addition of serious event (spontaneous abortion), Pregnancy details (Gestation Period changed from 4 weeks to 6 weeks), Expected Delivery Date); upgraded the seriousness of event maternal exposure during pregnancy, laboratory data (Ultrasound scan), Product (Indication changed from prophylactic vaccination to Prevention of Covid-19 (Covid-19 immunization).  20210754070-covid-19 vaccine ad26.cov2.s-Spontaneous abortion. Follow-up received regarding Clinical Details. This event(s) is considered not related. The event(s) 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(s) than the drug. Specifically: UNDERLYING DISEASE  20210754070-covid-19 vaccine ad26.cov2.s-maternal exposure during pregnancy. Follow-up received regarding Clinical Details. This event(s) is considered not related. The event(s) 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(s) than the drug. Specifically: SPECIAL SITUATIONS.