Gestational age at outcome (weeks): 33.1/premature delivery; Anemia; Vaccine exposure during pregnancy; This is a serious observational study case, initially received from other health professional on 07-Jun-2019, concerning a 20-year-old adult female pregnant subject of body weight: 94 lbs, height: 61.5 inches and body mass index (BMI): 17.5, enrolled in, 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 had one previous pregnancy with preterm live birth. The subject's historical condition included bacterial vaginosis (start date: 20-Aug-2018 and stop date: 27-Aug-2018) and the subject was treated with Metrogel (metronidazole). 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 concomitant medication included Prenatal vitamins (minerals NOS, vitamins NOS) for pregnancy.  The subject's last menstrual period (LMP) date was 23-Mar-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 22-Aug-2018, the subject underwent ultrasound test and no major congenital malformation was noted.  On 19-Sep-2018, the subject underwent Quad screen test and no major congenital malformation was noted.  On 18-Oct-2018, at approximately 30 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 the same day, after vaccination, the subject experienced anemia.   On 11-Dec-2018, the subject underwent ultrasound and no major congenital malformation was noted.  On 21-Dec-2018, 2 months and 3 days after vaccination, at gestational age of 33.1 weeks, the subject delivered a normal live female neonate (explicitly coded as premature delivery) via vaginal method of delivery. The neonate's birth weight was 3374 grams, head circumference was 31.8 cm and body length was 45.1 cm. The APGAR scores were 8 (one minute) and 9 (five minutes). APGAR score was not reported at 10 minutes. There were no major congenital malformations (MCM) identified at birth.   The outcome of the event anemia was not recovered.   The subject's estimated delivery date (EDD) was reported as 07-Feb-2019.  This case is linked to case 201903707 (baby case).; Reporter's Comments: A 20-year-old pregnant subject experienced anemia, on the same day after administration of study vaccine, at 30 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 events and hemodynamic changes associated with pregnancy, the event was assessed as not related to the vaccination. Considering the time frame of event with respect to vaccine administration, no evidence for a biological mechanism that could cause the event and risk factors (previous pregnancy with preterm live birth bacterial vaginosis treated with metronidazole), the event (premature delivery) was assessed as not related to the study vaccine. 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).