Delivery at 36.9 weeks of gestation; Vaccine exposure during pregnancy; This is an observational study case initially received on 03-Feb-2020, concerning a 33-year-old female pregnant subject of body weight 243.4 lbs, height 64 inches and body mass index (BMI) 41.8, enrolled in a prospective observational safety study.  The subject's current conditions included polycystic ovarian syndrome since Feb-2019, gestational diabetes mellitus since 02-Apr-2019 and  increased BMI.  The subject's concomitant medications included prenatal vitamins (unspecified vitamins and minerals) as neonatal care and Metformin HCL ER (metformin hydrochloride) for gestational diabetes.   The subject's obstetrical history noted that the subject had four previous pregnancies of full-term live birth 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 on 03-Jan-2019. The subject's estimated date of delivery (EDD) was reported as 10-Oct-2019, while corrected estimated date of delivery (CEDD) was reported as 07-Nov-2019. The type of pregnancy was singleton. The subject's partner age was 35.  On 02-Apr-2019, the subject underwent ultrasound and no MCMs were noted.  On 29-Apr-2019, the subject underwent first trimester screen and no MCMs were noted.  On 24-Jun-2019, the subject underwent ultrasound and no MCMs were noted.  On 12-Sep-2019, at approximately 32 weeks of gestation, the subject was administered Flu Vaccine Cell Subunit QIV NVD (Flucelvax QIVc) [influenza vaccine, subunit influenza virus vaccine polyvalent, batch number: 261207, dose: 0.5 mL, route of administration, anatomical location and expiration date: not reported] (explicitly coded as 'Vaccine exposure during pregnancy') for influenza immunisation.  At approximately (reported as) 36.9 weeks of gestation, the subject gave live birth to a female neonate via caesarean method. The characteristics of the neonate included birth weight: 3062 grams, length: 48.3 cm and head circumference was not reported. Appearance, pulse, grimace, activity, and respiration (APGAR) scores were 7 at one minute, 8 at five minutes and 9 at ten minutes. No MCMs were identified at the time of birth.   At the time of this report, the outcome for the event of 'premature delivery' was not reported.  The event of premature delivery' was considered as serious due to criterion of medical significance, per company.  The reporter did not provide causality assessment to Flucelvax QIVc.  This case is linked to case number 202001631 (corresponding baby case).  Company Comment: The pregnant subject developed premature delivery after vaccination with Flucelvax QIVc, administered at approximately 32 weeks of gestation (coded to Exposure during pregnancy). Chronology is compatible. Pregnant state, polycystic ovarian syndrome, gestational diabetes mellitus and obesity (body mass index 41.8) may provide alternative aetiology for the event. Causality was also confounded by therapy with concomitant medication, Metformin HCL ER (metformin hydrochloride). Considering all the above mentioned, causality between suspect product and the event premature delivery is assessed as unlikely related (defaults to "related" in the safety database for reporting purposes). Vaccine exposure during pregnancy is assessed as not related per company's conventions.; Sender's Comments: The pregnant subject developed premature delivery after vaccination with Flucelvax QIVc, administered at approximately 32 weeks of gestation (coded to Exposure during pregnancy). Chronology is compatible. Pregnant state, polycystic ovarian syndrome, gestational diabetes mellitus and obesity (body mass index 41.8) may provide alternative aetiology for the event. Causality was also confounded by therapy with concomitant medication, Metformin HCL ER (metformin hydrochloride). Considering all the above mentioned, causality between suspect product and the event premature delivery is assessed as unlikely related (defaults to "related" in the safety database for reporting purposes). Vaccine exposure during pregnancy is assessed as not related per company's conventions.