Foetal exposure during pregnancy; Low birth weight of 2438 g; This is an observational study case, initially received on 19-Feb-2021 from other health professional and concerned a male neonate, whose mother was 18-year-old, pregnant, female subject of body weight 121 lbs, height 64.5 inches and body mass index (BMI) 20.4, enrolled in, a prospective observational safety study.   The maternal concurrent conditions included anaemia and gestational thrombocytopenia. The mother's concomitant medications included Prenatal vitamins (minerals not specified (nos), vitamins nos) used for pregnancy, Injectafer (ferric carboxymaltose), ferrous sulfate and Ferralet (ferrous gluconate), all used for anemia.  The maternal obstetrical history noted that the neonate's mother had no previous pregnancies. The mother had no maternal or paternal history with major congenital malformations (MCMs). The neonate's mother did not use tobacco, alcohol or illicit drugs during pregnancy.  The mother's last menstrual period (LMP) date was 30-Jul-2019, the estimated delivery date (EDD) was reported as 05-May-2020, while the corrected estimated date of delivery (CEDD) was reported as 11-May-2020. The type of pregnancy was singleton.   On 24-Sep-2019, the ultrasound scan revealed no MCM.  On 29-Oct-2019, non-invasive prenatal test and nuchal translucency revealed no MCMs.  On 26-Nov-2019, maternal serum alpha-fetoprotein screening (MSAFP), serum markers revealed no MCMs.  On 07-Jan-2020, at approximately 23 weeks of gestation (calculated per LMP), the neonate's mother was administered Afluria QIV (Flu Vaccine Egg Split QIV CSL) (influenza vaccine; dose, anatomical location and route of administration: not reported) (explicitly coded as 'Foetal exposure during pregnancy') for influenza immunisation. The batch number reported was P100112488.  On the same day, 20-week anatomy ultrasound scan revealed no MCM.  At gestational age of 37 weeks (as reported), the mother delivered vaginally a live birth, male neonate. The neonate birth weight was 2438 grams, head circumference and length were not reported. The appearance, pulse, grimace, activity, and respiration (APGAR) scores at one, five and 10 minutes were not provided. No MCM was identified at birth.  The outcome of the event was not reported.   The reporter did not provide a causality assessment.  The event of 'low birth weight baby' was considered to be medically significant by a Physician within Seqirus's Pharmacovigilance and Risk Management Department.  This case is linked with the case 202002354, the corresponding mother case.  Company comment: A male neonate patient experienced low birth weight, approximately 14 weeks after maternal receipt of Afluria QIV. Chronology is plausible. As reported, the maternal obstetrical history noted that the neonate's mother had no previous pregnancies. The mother had no maternal or paternal history with major congenital malformations (MCMs). The neonate's mother did not use tobacco, alcohol or illicit drugs during pregnancy. The ultrasound scan revealed no MCM. With currently available information, causality for the event low birth weight is unassessable. The event foetal exposure during pregnancy was assessed as not related considering the intended use of the vaccine.      .; Sender's Comments: A male neonate patient experienced low birth weight, approximately 14 weeks after maternal receipt of Afluria QIV. Chronology is plausible. As reported, the maternal obstetrical history noted that the neonate's mother had no previous pregnancies. The mother had no maternal or paternal history with major congenital malformations (MCMs). The neonate's mother did not use tobacco, alcohol or illicit drugs during pregnancy. The ultrasound scan revealed no MCM. With currently available information, causality for the event low birth weight is unassessable. The event foetal exposure during pregnancy was assessed as not related considering the intended use of the vaccine.