Preterm delivery at 35.4 gestational weeks; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 06-Apr-2020, concerning a 25-year-old, pregnant female subject (Ethnicity: not reported) of body weight: 176 lbs, height: 69 inches and body mass index (BMI) 26, 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 medical history included body mass index high (BMI 26).    The subject's concomitant medication included Prenatal vitamins (unspecified vitamins and minerals) for pregnancy.   The subject's obstetrical history included three previous pregnancies with one full term live birth and two spontaneous abortions. The subject did not have a history of offspring with major congenital malformation (MCM). Also, the subject had no maternal or paternal history with MCMs. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.  The subject's last menstrual period (LMP) date was 17-May-2019, the estimated delivery date (EDD) and corrected estimated date of delivery (CEDD) were reported as 21-Feb-2020. The type of pregnancy was singleton.  On 21-Jun-2019, the subject underwent spinal muscular atrophy and cystic fibrosis mutation analysis and no MCM was noted.   On 23-Jul-2019, the subject underwent ultrasound scan and no MCM was noted.   On 06-Aug-2019, the subject underwent panorama test and no MCM was noted.   On 10-Sep-2019, the subject underwent ultrasound scan and no MCM was noted.   On 08-Oct-2019, at approximately 20 weeks of gestation (calculated per LMP), the subject was administered Flucelvax QIV (Flu Vaccine Cell Subunit QIV NVD) [influenza vaccine, subunit influenza virus vaccine polyvalent; dose: 0.5 ml, batch number: 261218, route of administration, anatomical location and expiry date: not reported] (explicitly coded as Vaccine exposure during pregnancy') for influenza immunisation.   On 08-Nov-2019, the subject underwent ultrasound scan and no MCM was noted.   At 35.4 weeks of gestation (as reported), the subject delivered live birth female neonate, by caesarean method of delivery. The neonate's birth weight was 2600 grams, head circumference and body length were not reported. The appearance, pulse, grimace, activity, and respiration (APGAR) scores were 9 at one minute and 9 at five minutes. APGAR score was not reported for 10 minutes. There was no major congenital malformation identified at birth.   At the time of this report, the outcome of event premature delivery' was not reported.   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.  This case is linked to 202002774 (corresponding baby case).  Company comment: The subject experienced premature delivery (at 35.4 weeks of gestation) 3 months and 10 days after vaccination with the suspect product Flucelvax QIV. (explicitly coded as Vaccine exposure during pregnancy'). Chronology seems unsuggestive. Medical history of two spontaneous abortions and high body mass index confounds causality. Causal relationship of the event 'vaccine exposure during pregnancy' is assessed as not related to suspect vaccine, while causal relationship between the suspect product and event of premature delivery is assessed as unlikely related (defaults to "related" in the safety database for reporting purposes).; Sender's Comments: The subject experienced premature delivery (at 35.4 weeks of gestation) 3 months and 10 days after vaccination with the suspect product Flucelvax QIV. (explicitly coded as Vaccine exposure during pregnancy'). Chronology seems unsuggestive. Medical history of two spontaneous abortions and high body mass index confounds causality. Causal relationship of the event 'vaccine exposure during pregnancy' is assessed as not related to suspect vaccine, while causal relationship between the suspect product and event of premature delivery is assessed as unlikely related (defaults to "related" in the safety database for reporting purposes).