Preterm labor in third trimester; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 15-Jul-2020, concerning a 29-year-old, pregnant, female subject of body weight 145 lbs, height 67 inches and body mass index (BMI) 22.7, enrolled in, a prospective observational study on pregnancy outcomes in women immunized with Flucelvax, seasonal cell culture influenza trivalent (TIVc) or quadrivalent (QIVc) vaccine during pregnancy.   The subject's current medical conditions included scoliosis of the spine.  The subject's concomitant medications included Prenatal vitamins (unspecified vitamins and minerals) as vitamin and TDAP (diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid) as vaccine.  The subject's obstetrical history noted that the subject had one previous pregnancy with one spontaneous abortion. The subject had no maternal or paternal history with major congenital malformations (MCMs). The subject had no history of offspring with MCMs. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.  The subject's last menstrual period (LMP) date was 09-Jul-2019, the estimated delivery date (EDD) was 14-Apr-2020 and the corrected estimated data of delivery (CEDD) was reported as 14-Mar-2020. The type of pregnancy was singleton.  On 03-Oct-2019, at approximately 12 weeks of gestation (calculated per LMP), 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: 261727, anatomical location, route of administration and expiration date: not reported] (explicitly coded as Vaccine exposure during pregnancy') for an influenza immunisation.   On the same day, the subject underwent nuchal translucency test and first trimester screen and no MCM was noted.  On 29-Oct-2019, the subject underwent maternal serum alpha-fetoprotein screening (MSAFP) / serum markers and second trimester screen and no MCM was noted.  On 25-Nov-2019, the subject underwent anatomy ultrasound and no MCM was noted.  On 20-Feb-2020, the preterm labor in third trimester was noted as pregnancy complication.  On 23-Mar-2020, the subject underwent ultrasound growth and no MCM was noted.  At gestational age of 39,9 weeks (as reported), the subject vaginally delivered live male neonate. The neonate's birth weight was 3770 g, head circumference and length were not reported. Appearance, pulse, grimace response, activity, respiration (APGAR) score in one minute was 8, in five minutes was 9 and in ten minutes was not reported. No MCM noted at birth.  The outcome of the event missed labor' was resolved, uo 21-Feb-2020.  The event of missed labor' was considered serious due to criterion of medical significance, per company.  The reporter did not provide causality assessment to Flucelvax QIV.  Company comment: A 29-year-old pregnant subject experienced missed labour (preterm labor in third trimester) four months after administration of Flucelvax QIVc. Chronology is unssugestive. The subject's current medical conditions included scoliosis of the spine, which may have contributed to development of the event. Causal role of the suspect product is assessed as not related due to biological implausibility and unsuggestive chronology. Vaccine exposure during pregnancy was assessed as unrelated per company's conventions.; Sender's Comments: A 29-year-old pregnant subject experienced missed labour (preterm labor in third trimester) four months after administration of Flucelvax QIVc. Chronology is unssugestive. The subject's current medical conditions included scoliosis of the spine, which may have contributed to development of the event. Causal role of the suspect product is assessed as not related due to biological implausibility and unsuggestive chronology. Vaccine exposure during pregnancy was assessed as unrelated per company's conventions.