Gestational age at pregnancy outcome 35.9 weeks/Premature delivery; Vaccine exposure during pregnancy; This is a serious observational study case, initially received from other health professional on 23-Jul-2019, concerning a 26-year-old adult female pregnant subject of weight 206 lbs, 65 inches height and body mass index (BMI) 34.3, enrolled in study on pregnancy outcomes in women immunized with Afluria QIV, a seasonal quadrivalent vaccine, during pregnancy.  The subject had no obstetrical history. The subject had no history of offspring with major congenital malformation. The subject had no maternal or paternal history with major congenital malformations. The subject's current condition included polycystic ovaries. The subject's Rhesus antibodies (RhD) was found to be negative. The subject's concomitant medication included prenatal vitamins (minerals NOS, vitamins NOS) as supplement.   The subject's last menstrual period (LMP) date was 22-Oct-2018 and type of pregnancy was singleton. The subject used tobacco during pregnancy and consumed 10 cigarettes per day during pregnancy. The subject did not have a prior history of use of alcohol or illicit drugs during pregnancy. The subject's pregnancy status was collected and there were no complications noted.  On 21-Dec-2018, at gestational age of 8 weeks, the pregnant subject was administered Flu Vaccine Egg Split QIV CSL [influenza vaccine, batch number: YF42609, dose, route of administration, anatomical location, and expiry date: not reported] (explicitly coded as vaccine exposure during pregnancy) for an unknown indication. On the same day, the subject underwent ultrasound test and no major congenital malformation was noted.  On 25-Jan-2019, the subject underwent nuchal translucency and inheri test, no major congenital malformation was noted. On 15-Mar-2019 and 12-Apr-2019, the subject underwent ultrasound test and no major congenital malformation was noted.   At gestational age of 35.9 weeks, the subject gave a live birth to a female neonate (coded as premature delivery) by vaginal method. The characteristics of neonate included birth weight: 3090 grams, head circumference: no data, body length: no data, appearance, pulse, grimace, activity and respiration (APGAR) scores 8 at one minute, 9 at five minutes and for ten minutes: no data. There were no major congenital malformations identified at birth.  The subject's estimated date of delivery (EDD) was reported as 29-Jul-2019 and corrected estimated date of delivery (CEDD) was reported as 01-Aug-2019.  This case is linked to the case 201904219 (baby case).; Reporter's Comments: A 26-year-old female pregnant subject experienced premature delivery at 35.9 weeks of gestational age, 6 months 12 days after receipt of Flu Vaccine Egg Split QIV (considered as vaccine exposure during pregnancy). Considering the time frame of the events, the time to onset of event premature delivery considered as implausible. Hence, the event premature delivery assessed as not related to study vaccine. The event vaccine exposure during pregnancy assessed as not related considering the intended use of the vaccine. The company assessed the case as serious (medically significant).