PARTIAL PLACENTAL RETENTION; MATERNAL EXPOSURE DURING PREGNANCY; PREMATURE DELIVERY; HEADACHE; NAUSEA; This solicited pregnancy report received from a patient concerned a 35 year old female. The patient was enrolled in a non-company sponsored study. The patient's weight, height, and medical history were not reported. The patient was gravida 1, para 1. The first day of the last menstrual period (LMP) was calculated to be 13-FEB-2021. The patient initiated treatment with covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: 1805031 expiry: UNKNOWN) dose was not reported, 1 total administered on 09-AUG-2021 for covid-19 immunisation at a gestational age of 25 weeks and two days. Age at time of vaccination 35 years old. No concomitant medications were reported. On 09-AUG-2021, the patient had maternal exposure during pregnancy, headache and nausea. On 29-OCT-2021, at gestational age 36 weeks and six days, the patient delivered vaginally a live, pre-term, male neonate and experienced premature delivery. One month later, the patient was hospitalized for dilation and curettage procedure due to partial placental retention. The number of days hospitalized was not reported. The estimated delivery date (EDD) was reported to be 20-NOV-2021. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The patient recovered from partial placental retention on 2021, maternal exposure during pregnancy on 29-OCT-2021, and headache, and nausea on 10-AUG-2021, and the outcome of premature delivery was not reported. The reporter considered the causality between covid-19 vaccine ad26.cov2.s and partial placental retention, maternal exposure during pregnancy and premature delivery as not related, and between covid-19 vaccine ad26.cov2.s, and headache, and nausea as related.  This report was serious (Hospitalization Caused / Prolonged). This parent/child case is linked to 20220809205.  This case was reassessed as serious based on additional information received from consumer on 09-FEB-2022, the following information was updated and incorporated into case narrative: Pregnancy information (estimated delivery date, end of pregnancy added, child information (sex), added events (premature delivery and partial placental retention), the outcome was updated for events maternal exposure during pregnancy, headache, nausea (from unknown to recovered), dose number in series, suspect product (batch number), linked AER added and narrative updated.; Sender's Comments: V1: Follow up information received in the current version is regarding new events of partial placental retention and premature delivery, Pregnancy information, the outcome updated for events maternal exposure during pregnancy, head ache, nausea (from unknown to recovered), dose number in series, suspect product (batch number), linked AER added, narrative updated. 20211148570-covid-19 vaccine ad26.cov2.s-partial placental retention. The case causality is considered NOT RELATED. Rationale: Preterm delivery is major confounding factor. 20211148570-covid-19 vaccine ad26.cov2.s-Maternal exposure during pregnancy. 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. Therefore, this event(s) is considered not related.