Gestational age at pregnancy outcome (weeks): 35.3/Premature delivery; Vaccine exposure during pregnancy; This is a serious observational study case initially received from other health professional on 20-Jun-2019, concerning a 25-year-old adult female pregnant subject of weight 107 lbs, 60 inches height and body mass index (BMI) 20.9, enrolled in V130_11OB, a prospective observational safety study on pregnancy outcomes in women immunized with seasonal cell culture influenza trivalent (TIVc) or quadrivalent (QIVc) vaccine during pregnancy.  The subject's historical conditions included bacterial vaginosis (start date: 06-Sep-2018; stop date: 16-Sep-2018 and was treated with Metrogel) and yeast infection (start date: 06-Sep-2018; stop date: 07-Sep-2018 and was treated with Diflucan).   The subject had one previous pregnancy with full term live birth. The subject did not have a history of offspring with major congenital malformation. On an unknown date, the subject's family history of major congenital malformation was collected, and the subject had no maternal or paternal history with major congenital malformations.    The subject's last menstrual period (LMP) date was 25-Jul-2018. The type of pregnancy was singleton. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.  On an unknown date, the pregnancy status of the subject was collected, and no pregnancy complications were noted.   On 23-Aug-2018, at 4 weeks of gestational age, the subject was administered prenatal vitamins (concomitant medication; dose: 1, unit: tablet, frequency: QD, route: oral; stop date: 29-Mar-2019) for pregnancy.   On 17-Oct-2018, at approximately 12 weeks of gestation, the pregnant subject was administered Flu Vaccine Cell Subunit QIV NVD (influenza vaccine, subunit influenza virus vaccine polyvalent, batch number: 252664, dose, route of administration, expiry date and anatomical location: not reported) (explicitly coded as vaccine exposure during pregnancy) for an unknown indication.  On 17-Oct-2018, the subject underwent quadruple screening, spinal muscular atrophy test and no major congenital malformation was noted.  On 09-Jan-2019, the subject underwent ultrasound test and no major congenital malformation was noted.  On 30-Jan-2019, the subject underwent ultrasound test and no major congenital malformation was noted.  5 months and 12 days after vaccination, the subject gave a live birth to a pre-term normal male neonate at 35.3 weeks gestation (explicitly coded as premature delivery). The delivery method was vaginal and no complications or no major congenital malformation (MCM) was identified at birth. The neonate's birth weight was 3005 grams, head circumference was 32.4 cm and body length were 49.5 cm. The APGAR scores were 8 (one minute) and 9 (five minutes). APGAR score was not reported for 10 minutes.   The outcome of the events was unknown.  The subject's estimated date of delivery (EDD) was reported as 01-May-2019.; Reporter's Comments: A 25-year-old pregnant subject experienced premature delivery, 5 months and 12 days after administration of study vaccine, at 12 weeks of gestation (coded to Exposure during pregnancy). Considering the implausible temporal relationship between vaccination and reported event, no evidence for a biological mechanism that could cause the event and complications (bacterial vaginosis treated with Metrogel and yeast infection treated with Diflucan) , the event was assessed as not related to the study vaccination. The decision to administer a vaccine during pregnancy is related to medical decision making by the mother and her physician and is not related to any property of the medication. The event of exposure during pregnancy was assessed as not related considering the intended use of the vaccineThe company assessed the case as serious (medically significant).