Missed abortion; Twin B non-viable; Twin A was blighted ovum; Vaccine exposure during pregnancy; This is an observational study case initially received on 06-Nov-2019, concerning a 28-year-old, pregnant female subject of body weight 126 lbs, height 60 inches and body mass index (BMI) 24.6 enrolled in a prospective observational safety study.  The subject's obstetrical history noted that the subject had one previous pregnancy with elective abortion. No birth defects were noted. The subject had no history of offspring with major congenital malformation (MCM). Also, the subject had no maternal or paternal history with MCM. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.   The subject's last menstrual period (LMP) date was 22-Aug-2019. The subject's estimated date of delivery (EDD) was reported as 12-Jun-2020 and corrected estimated date of delivery (CEDD) was reported as 13-Jun-2020. The type of pregnancy was multiple.   The subject's current conditions included anxiety and attention deficit-hyperactivity disorder. The subject's concomitant medications included prenatal vitamins (minerals NOS, vitamins NOS) for pregnancy and clonazepam for anxiety and attention deficit-hyperactivity disorder.  On 18-Oct-2019, at 6 weeks of gestation, the subject underwent dating ultrasound. As reported, intrauterine pregnancy was noted with uncertain cardiac activity. No MCMs were noted.  On 23-Oct-2019, at approximately 7 weeks of gestation, the subject was administered Flu Vaccine Egg Split QIV CSL (Afluria QIV) [influenza vaccine, subunit influenza virus vaccine polyvalent, cell cultured derived, batch number: P100123038, dose, route of administration, anatomical location and expiration date: not reported] (explicitly coded as 'Vaccine exposure during pregnancy') for an influenza immunisation.   On 02-Nov-2019, at approximately 8.1 weeks of gestation, the subject underwent ultrasound and non-viable twin pregnancy was noted,  twin A was blighted ovum, and no cardiac activity for twin B. No MCMs were noted.  On the same day, the subject received misoprostol at a dose of 200 mcg and had missed abortion due to non-viable pregnancy with both twins.   On 04-Nov-2019, the subject underwent complete blood count with differential, type and screen. The complete blood count was reported as normal. Positive Rh factor was noted.   The case was assessed as serious.   The reporter did not provide causality assessment to Afluria Quadrivalent.  Company comment: The subject experienced foetal death, anembryonic gestation and abortion missed 10 days after vaccination with the suspect product Afluria QIV. Reportedly, vaccination occurred during pregnancy at gestational age of 7 weeks. Chronology is unsuggestive but plausible. Clonazepam as concomitant medication may provide alternative aetiology due to its known harmful pharmacological effects on pregnancy and the foetus/newborn child. Vaccine exposure during pregnancy is assessed as not related per company's conventions. For events foetal death, anembryonic gestation and abortion missed, causality between suspect product and the events is assessed as unlikely related.; Sender's Comments: The subject experienced foetal death, anembryonic gestation and abortion missed 10 days after vaccination with the suspect product Afluria QIV. Reportedly, vaccination occurred during pregnancy at gestational age of 7 weeks. Chronology is unsuggestive but plausible. Clonazepam as concomitant medication may provide alternative aetiology due to its known harmful pharmacological effects on pregnancy and the foetus/newborn child. Vaccine exposure during pregnancy is assessed as not related per company's conventions. For events foetal death, anembryonic gestation and abortion missed, causality between suspect product and the events is assessed as unlikely related.