Polyhydramnios; Anemia; Vaccine exposure during pregnancy; This is a serious observational study case, initially received from other health professional on 18-Jun-2019, concerning an 18-year-old, adult female pregnant subject of body weight: 113.6 lbs, height: 56 inches and body mass index (BMI): 25.5 enrolled in a prospective observational study on pregnancy outcomes in women immunized with Afluria QIV, a seasonal quadrivalent vaccine during pregnancy.   The subject had no previous pregnancy. 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 22-Sep-2018. The type of pregnancy was singleton. The subject did not consume alcohol, tobacco and illicit-drug during pregnancy.  On 21-Nov-2018, at gestational age of approximately 8 weeks, the 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 of vaccination, the subject underwent ultrasound scan and no congenital malformation was noted. On 19-Dec-2018, the subject underwent, inheritest core, nuchal translucency and sequential 1 screening and no congenital malformations were noted. On 16-Jan-2019, the subject underwent sequential 2 screening and no congenital malformation was noted.  On 06-Jun-2019, 6 months and 6 days after the vaccination, the subject experienced anemia. On the same day, the subject started the treatment with iron (dose: 325 mg, daily, orally, continued) for anemia.   at gestational age of 38 weeks the subject gave a live birth to a normal female neonate via vaginal delivery. The subject was noted to have polyhydramnios as pregnancy complication. The infant's birth weight was 3118 grams and no data were reported for head circumference and body length. Appearance, pulse, grimace, activity and respiration (APGAR) scores were 9 at one minute and 5 minutes. There was no data reported for APGAR score at ten minutes. No major congenital malformation was identified at birth.  The outcome of the event polyhydramnios was not reported and outcome of the event anemia was not recovered.  The subject's corrected estimated delivery date (CEDD) was reported as 29-Jun-2019 and estimated delivery date (EDD) was reported as 30-Jun-2019.; Reporter's Comments: A 18-year-old female pregnant subject was diagnosed with anaemia more than 6 months post-vaccination with Flu vaccine Egg split QIV and noted to have polyhydramnios as pregnancy complication at the time of delivery. These events can be explained by the concurrent state of pregnancy rather than suspect vaccine as there are no known biological mechanism to explain these events following 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 vaccine. The company assessed the case as serious (medically significant).