miscarriage; This is a spontaneous report received from contactable reporter(s) (Physician and Nurse), Program ID: (Not available).  A 37-year-old female patient (pregnant) received BNT162b2 (BNT162B2), on 01Feb2022 at 12:40 as dose 4 (booster), single (Batch/Lot number: unknown) at the age of 37 years intramuscular, in right deltoid for covid-19 immunisation. The patient's relevant medical history included: "Diabetes Mellitus Type 2", start date: 2003 (ongoing); "Anxiety", start date: 2002 (ongoing); "PCOS", start date: 2002 (ongoing); "Endometriosis", start date: 2002 (ongoing); "Inflamed Gallbladder", start date: 2003, stop date: 2003; "Cholecystectomy", start date: 2003, stop date: 2003; "Endometriosis Removal", start date: 2005, stop date: 2005; "C-Section", start date: 14Mar2015, stop date: 14Mar2015; "Endometriosis Removal", start date: 2016, stop date: 2016; "1 previous pregnancy" (unspecified if ongoing), notes: Live Birth; "did not smoke tobacco" (unspecified if ongoing). Concomitant medication(s) included: INOSITOL taken for type 2 diabetes mellitus, start date: 2017 (ongoing); XANAX taken for anxiety, start date: 2010 (ongoing); METFORMIN taken for type 2 diabetes mellitus, start date: 2021 (ongoing). Vaccination history included: BNT162b2 (DOSE 1, SINGLE, at 13:20, via IM in left deltoid), administration date: 29Oct2020, when the patient was 35-year-old, for COVID-19 immunization; BNT162b2 (DOSE 2, SINGLE, at 13:40, via IM in left deltoid), administration date: 17Nov2020, when the patient was 35-year-old, for COVID-19 immunization; BNT162b2;placebo (DOSE 3, SINGLE, at 13:40, via IM in left deltoid), administration date: 20Jul2021, when the patient was 36-year-old, for COVID-19 immunization. The following information was reported: ABORTION SPONTANEOUS (medically significant) with onset 15Jun2022, outcome "not recovered", described as "miscarriage". The patient underwent the following laboratory tests and procedures: Pregnancy test urine: (27Apr2022) noted that the patient was pregnant.  Clinical course: Patient came into research center on 27Apr2022 for visit. Upon doing a urine pregnancy test, it was noted that the patient was pregnant. Patient had not been to a doctor for confirmation due to only finding out on the day she was at research center. The pregnancy details were the following: The patient first missed menstrual period was on 30Apr2022 (date was correct for first menstrual period missed). Patient came into the office and tested positive for pregnancy a couple days before her missed menstrual cycle. Gestation at time of initial exposure was first trimester. The patient had 1 previous pregnancy with live birth. The patient did not smoke tobacco, drank alcohol or used illicit drugs during this pregnancy. Upon follow up on 07Oct2022, investigators spoke to this patient this week and she was doing well, and her due date was some time in Jan2023. The patient began this trial on 01Feb2022 and after site confirmed pregnancy on 27Apr2022, she was discontinued from the trial. On 15Jun2022, patient had a miscarriage, and the pregnancy was lost. Outcome of pregnancy was spontaneous abortion/miscarriage on 15Jun2022. Gestational weeks at birth was unknown. The action taken in response to the event for study vaccine was not applicable. Outcome of the event was not recovered (reported as recovered on 15Jun2022 by investigator). Upon follow up 08May2023, The subject discontinued from the trial on 27Apr2022. As per safety narrative, the abnormal pregnancy outcome-"Miscarriage" occurred on 15Jun2022. The abnormal outcome was outside the trial period. Currently, the event is validated in system as "Miscarriage". However, the record in study database is inactivated because at time of discontinuation, "Pregnancy" was the case and miscarriage was outside the trial period. Additionally, (name) provided an e-mail exchange regarding a similar case report that occurred in the C4591001 protocol. See attached. Due to regulatory requirements maintaining the case in the Safety Database was considered to be an acceptable discrepancy. Based on the information provided below, the event "Miscarriage" is currently validated in system. However, checking the agency report, we still have open agency letter site stating the following message. Per protocol, "abnormal pregnancy outcomes are considered SAES. If the outcome of The pregnancy meets the criteria for an SAE (ie, ectopic pregnancy, spontaneous Abortion (including miscarriage and missed abortion), intrauterine fetal demise, Neonatal death, or congenital anomaly), the investigator should follow the Procedures for reporting SAES." the pregnancy outcome is miscarriage, which should be Reported as SAE per the protocol, however, the SAE form states "the SAE was deemed not An SAE and the event can be removed from the system database".   The investigator considered there was not a reasonable possibility that the event "miscarriage" was related to study vaccine, concomitant drugs, or clinical trial procedure.  Follow-up (02May2022): This is a follow-up report from an interventional study source for Protocol C4591031 sponsored by BioNTech, managed, and reported by Pfizer on the sponsor's behalf. Updated information: historical vaccines, study vaccine (dose description and anatomical location), concomitant drugs, clinical course (first missed menstrual period), study protocol.  Follow-up (25May2022): This is a follow-up report from an interventional study source for Protocol C4591031 sponsored by BioNTech, managed, and reported by Pfizer on the sponsor's behalf. Updated information: study vaccine (dose and visit number added). Additionally, medical history (stop date of Diabetes Mellitus Type 2 updated), dose description updated and concomitant drug (multivitamin) updated.  Follow-up (01Jun2022): This is a follow-up report from an interventional study source for Protocol C4591031 sponsored by BioNTech, managed, and reported by Pfizer on the sponsor's behalf. Updated information: clinical course (tested positive for pregnancy a couple days before her missed menstrual cycle).  Amendment: This follow-up report is being submitted to amend previous information: removed vaccine dose and updated narrative to include "The patient was participating in Sub-study D when the event occurred."  Follow-up (07Oct2022): This is a follow-up report from an interventional study source for Protocol C4591031 sponsored by BioNTech, managed, and reported by Pfizer on the sponsor's behalf. Updated information: clinical course (patient status and discontinued from the trial).  Follow-up (27Jan2023): This is a follow-up report from an interventional study source for Protocol C4591031 sponsored by BioNTech, managed and reported by Pfizer on the sponsor's behalf. Updated information: pregnancy details and reaction data (event updated to spontaneous abortion).  Follow-up (02Mar2023): This is a follow-up report from an interventional study source for Protocol C4591031 sponsored by BioNTech, managed and reported by Pfizer on the sponsor's behalf. Updated information: reaction data (onset date updated from 27Apr2022 to 15Jun2022, outcome reported as to recovered on 15Jun2022 by investigator) and clinical course (patient lost pregnancy).  Follow-up (08Mar2023): This is a follow-up report from an interventional study source for Protocol C4591031 sponsored by BioNTech, managed and reported by Pfizer on the sponsor's behalf. Updated information: reaction data (SAE term updated from "spontaneous Abortion/Miscarriage" to "miscarriage").  Follow-up (29Mar2023): This is a follow-up report from an interventional study source for Protocol C4591031 sponsored by BioNTech, managed and reported by Pfizer on the sponsor's behalf. Updated information: Case validity (Case downgraded to invalid as Other-Non serious clinical study report).  Amendment: This follow-up report is being submitted to amend previous information: to amend case validity, seriousness criteria for miscarriage added as Medically Significant.  Follow-up (08May2023): This is a spontaneous follow-up report received in response to the mail trail sent regarding the confirmation below mentioned query. The response included: Updated information included: Report type and narrative updated.  The information on the batch/lot number for BNT162b2 has been requested and will be submitted if and when received.; Sender's Comments: Based on the lack of a plausible pathophysiological mechanism for the event, there was not a reasonable possibility that the event "miscarriage" was related to study vaccine, concomitant drugs, or clinical trial procedure.