Premature delivery at 30.3 weeks of gestation; Precipitous delivery; Bacterial vaginosis; Vaccine exposure during pregnancy; This is an observational study case initially received on 02-Dec-2019, concerning a 21-year-old female pregnant subject of body weight 178.6 lbs, height 64 inches and body mass index (BMI) 30.7, enrolled in a prospective observational safety study.  The subject's current medical condition included BMI high, nausea and Rhesus (Rh) antibodies (anti D) negative.   The subject's concomitant medications included Flintstones gummies (unspecified vitamins) as vitamin, Diclegis (doxylamine succinate and pyridoxine hydrochloride) for nausea and TDAP (diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid) as vaccine.  The subject's obstetrical history noted that the subject had two previous pregnancies with one spontaneous abortion and one full term live birth by caesarean with no birth defects. The subject had no history of offspring with major congenital malformation (MCM). Also, the subject had no maternal or paternal history with MCM. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.   The subject's last menstrual period (LMP) date was not reported. The subject's estimated date of delivery (EDD) was not reported, while corrected estimated date of delivery (CEDD) was reported as 28-May-2020. The type of pregnancy was singleton.  On 20-Oct-2019, the subject underwent dating scan and no MCMs were noted.  On 29-Oct-2019, at unknown week of gestation, the subject was administered Flucelvax QIVc (Flu Vaccine Cell Subunit QIV NVD) [influenza vaccine, subunit influenza virus vaccine polyvalent,  dose: 0.5 mL, batch number: 2612233, route of administration, anatomical location and expiration date: not reported] (explicitly coded as 'Vaccine exposure during pregnancy') for an influenza immunisation.   On 21-Nov-2019, 23 days after vaccination, the subject developed bacterial vaginosis and started corrective treatment with metronidazole (one tablet, twice daily, orally). On the same day, the subject underwent first trimester screen and no MCMs were noted.  On 19-Dec-2019, the subject underwent maternal serum alpha fetoprotein screening (MSAFP) and second trimester screen. No MCMs were noted.  On 08-Jan-2020, the subject underwent anatomy ultrasound and no MCMs were noted.  At gestational age of 30.3 weeks (as reported), the subject vaginally delivered a live birth, female neonate. The delivery was precipitous. The neonate's birth weight was 1389 grams, head circumference and body length were not reported. The appearance, pulse, grimace, activity, and respiration (APGAR) scores at one minute, at five minutes and at ten minutes were not reported. The neonate was put in the neonatal intensive care unit (NICU). There was no information if MCM was identified at birth.  The outcome of the events 'bacterial vaginosis', premature delivery' and 'precipitate labour, with delivery' was not resolved.  The event of premature delivery' was assessed as serious due to the criterion of medical significance, per company.   The reporter did not provide causality assessment to Flucelvax QIVc.  This case is linked to 202002957 (corresponding baby case).  Follow up information received by other health professional on 16-Jan-2020: CEDD updated, new prenatal tests added. Narrative was amended accordingly.  Non-significant follow up information received by other health professional on 17-Feb-2020: It was reported that the subject's LMP and stop date for the event of bacterial vaginosis' was unknown. No changes were made in the narrative.  Follow up information received from other health professional on 15-Apr-2020: TDAP added as concomitant. Pregnancy outcome received. Events premature delivery' and 'precipitate labour, with delivery' were added. Case upgrade to serious case. Stop date for 'Vaccine exposure during pregnancy' was added and the outcome was changed from not reported to resolved. The narrative was amended accordingly.  Company Comment: The subject experienced bacterial vaginosis 23 days after vaccination with the suspect product, Flucelvax QIV. The patient experienced premature delivery and precipitate labour 4 months and 21 days post vaccination. Reportedly, vaccination occurred during pregnancy. Pregnant state may provide alternative aetiology for the event. Vaccine exposure during pregnancy is assessed as not related per company's conventions. Causality between suspect product and the event bacterial vaginosis is assessed as unlikely related (defaults to related for reporting purposes). For the events premature delivery and precipitate labour, causality is assessed as not related due to unsuggestive chronology.; Sender's Comments: The subject experienced bacterial vaginosis 23 days after vaccination with the suspect product, Flucelvax QIV. The patient experienced premature delivery and precipitate labour 4 months and 21 days post vaccination. Reportedly, vaccination occurred during pregnancy. Pregnant state may provide alternative aetiology for the event. Vaccine exposure during pregnancy is assessed as not related per company's conventions. Causality between suspect product and the event bacterial vaginosis is assessed as unlikely related (defaults to related for reporting purposes). For the events premature delivery and precipitate labour, causality is assessed as not related due to unsuggestive chronology.