Cervical insufficiency; Spontaneous abortion (complete miscarriage) at 18 weeks of gestational period; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 10-Jan-2020, concerning a 34-year-old, female pregnant subject of body weight: 217 lbs, height: 62 inches and body mass index (BMI): 39.7 enrolled in, a prospective observational safety study.  The subject's medical history included migraines, hypothyroidism and high body mass index. The subject's concomitant medications included topiramate for migraines, levothyroxine for hypothyroidism and Prenatal vitamin (unspecified vitamins) for obstetrics (OB) care.  The subject's obstetrical history included one previous pregnancy that ended as spontaneous abortion. The subject had no maternal/paternal history with major congenital malformations (MCM).    The subject's last menstrual period (LMP) date was 22-Jul-2019. The type of pregnancy was singleton. The subject's estimated delivery date (EDD) was 05-May-2020 and corrected estimated delivery date (CEDD) was not reported. The subject did not consume tobacco, alcohol and illicit-drugs during pregnancy.  On 07-Oct-2019, at gestational age of 11 weeks, the subject was administered Flu Vaccine Cell Subunit QIV NVD (influenza vaccine, subunit influenza virus vaccine polyvalent, batch number: 261727, dose: 0,5 ml, route of administration, anatomical location and expiry date: not reported) (explicitly coded as Vaccine exposure during pregnancy') for influenza immunisation.  On an unspecified date in 2019, unknown amount of time after vaccination, the subject developed cervical insufficiency.  On 03-Dec-2019, approximately two months after vaccination, at the gestational age of 18 weeks, the subject had spontaneous abortion (complete miscarriage). The subject underwent dilatation and curettage (D&C).  At the time of initial report, the outcome of the events was not reported.  The events of spontaneous abortion and cervical insufficiency were assessed as serious due to the criterion of medical significance per company.  The reporter did not provide the causality assessment to Flucelvax.  Company comment: The subject experienced abortion spontaneous and cervical incompetence after vaccination with the suspect product, Flu Vaccine Cell Subunit QIV NVD. Reportedly, vaccination occurred during pregnancy at 11 weeks of gestation.  Chronology is plausible.  Medical history of obesity (body mass index 39.7) and hypothyroidism may provide alternative aetiology for the events. Causality was also confounded by therapy with concomitant medications topiramate and levothyroxine. Vaccine exposure during pregnancy is assessed as not related per company's conventions. Causality between suspect product and the events abortion spontaneous and cervical incompetence is assessed as unlikely related (defaults to related for reporting purposes).; Sender's Comments: Company comment: The subject experienced abortion spontaneous and cervical incompetence after vaccination with the suspect product, Flu Vaccine Cell Subunit QIV NVD. Reportedly, vaccination occurred during pregnancy at 11 weeks of gestation.  Chronology is plausible.  Medical history of obesity (body mass index 39.7) and hypothyroidism may provide alternative aetiology for the events. Causality was also confounded by therapy with concomitant medications topiramate and levothyroxine. Vaccine exposure during pregnancy is assessed as not related per company's conventions. Causality between suspect product and the events abortion spontaneous and cervical incompetence is assessed as unlikely related (defaults to related for reporting purposes).