Dysmature placenta; Vaccine exposure during pregnancy; This is an observational study case, initially received on 02-Jul-2019, concerning a 21- year-old, pregnant, female subject of body weight: 179 lbs, height: 61 inches and body mass index (BMI): 33.8, enrolled in a prospective observational safety study.   The subject's historical condition included vaginitis. The subject's current conditions constituted nausea and glycogen storage disease.   The subject's historical drug included Metrogel (metronidazole) for vaginitis. The subject's concomitant medications included Prenatal vitamins (unspecified minerals and vitamins) for pregnancy, promethazine and Reglan (metoclopramide), both for nausea.  The subject's obstetrical history noted that the subject had one previous full-term, live birth pregnancy with no birth defects. The subject had no history of offspring with major congenital malformation (MCM). The subject's brother had Down syndrome. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.   The subject's last menstrual period (LMP) date was on 20-Jul-2018, the estimated delivery date (EDD) was reported as 26-Apr-2019, while corrected estimated date of delivery (CEDD) was reported as 15-May-2019. The type of pregnancy was singleton.   On 04-Oct-2018, the subject underwent ultrasound scan and no MCMs were noted.   On 01-Nov-2018, at gestational age of 14 weeks (calculated per LMP), the subject was administered Flucelvax QIVc (Flu Vaccine Cell Subunit QIV NVD) [influenza vaccine, subunit influenza virus vaccine polyvalent; batch number: 252664, dose: 0.5 ml, route of administration, anatomical location and expiry date: not reported] (explicitly coded as Vaccine exposure during pregnancy') for influenza immunization.  On 29-Nov-2018, the subject underwent ultrasound scan no MCMs were noted.   On 03-Jan-2019, the subject also underwent a quad screen test and no MCMs were noted.   On 27-Mar-2019, the subject developed dysmature placenta, reported as pregnancy complication.  On the same day, the subject underwent ultrasound scan and no MCMs were noted.  On 03-Apr-2019 and 11-Apr-2019, the subject underwent non-stress test for dysmature placenta. No MCMs were noted.  On 18-Apr-2019, the subject underwent ultrasound scan and no MCMs were noted.  On 30-Apr-2019, the subject underwent non-stress test for dysmature placenta and no MCMs were noted.  On 08-May-2019, the subject again underwent ultrasound scan and no MCMs were noted.  At 39.7 weeks of gestation, the subject gave live birth to a female neonate vaginally. The characteristics of the neonate included birth weight: 3515 grams, head circumference: 35.6 cm, length: 52.1 cm and appearance, pulse, grimace, activity, and respiration (APGAR) scores were 9 at one minute and 10 at five minutes. No MCMs were identified at the time of birth.   The outcome, of the event of dysmature placenta was resolved.  The reporter did not provide causality assessment to Flucelvax QIVc.  Follow up was received from other health professional on 06-Aug-2019: The event of dysmature placenta was added, and labs were updated. Narrative was amended accordingly.  Follow up was received from other health professional on 04-Mar-2020: The start date was reported for the event of dysmature placenta'. Narrative was amended accordingly.  Company Comment: The subject experienced placental disorder approximately five months after vaccination with the suspect product Flucelvax QIVc. Chronology is implausible. Medical history of glycogen storage disease may have contributed to development of the event. Causality was confounded by therapy with concomitant drugs, promethazine and Reglan (metoclopramide). Considering all the above mentioned, causal relationship between the suspect product and the event is assessed as not related. Vaccine exposure during pregnancy is assessed as not related per company conventions.; Sender's Comments: The subject experienced placental disorder approximately five months after vaccination with the suspect product Flucelvax QIVc. Chronology is implausible. Medical history of glycogen storage disease may have contributed to development of the event. Causality was confounded by therapy with concomitant drugs, promethazine and Reglan (metoclopramide). Considering all the above mentioned, causal relationship between the suspect product and the event is assessed as not related. Vaccine exposure during pregnancy is assessed as not related per company conventions.