Neonate's birth weight was 4791 grams/large for gestational age; Fetal exposure during pregnancy; This is a serious spontaneous case, initially received from other health professional on 31-May-2019, concerning a male neonate patient.   The patient's mother was 24-year-old with body weight: 180 lbs, height: 66 inches and body mass index (BMI): 29.0 and had no obstetrical history. The patient's mother had no history of offspring with major congenital malformations and maternal or paternal history with major congenital malformations. The patient's mother did not have a prior history of use of tobacco, alcohol or illicit drugs during pregnancy. The pregnancy status of patient's mother was collected, and no pregnancy complications were noted.  The patient's mother had no current conditions. The patient mother's concomitant medications included prenatal vitamins (minerals NOS, vitamins NOS) for pregnancy, ferrous sulphate for anemia and Colace (docusate sodium) as stool softener.  The patient's mother last menstrual period (LMP) date was 18-May-2018 and the type of pregnancy was singleton.  On 27-Jun-2018, the patient's mother underwent hemoglobinopathy evaluation (hemoglobinopathy eval), spinal muscular atrophy, cystic fibrosis and no major congenital malformations were noted.  On 09-Jul-2018 and 31-Aug-2018, the patient's mother underwent ultrasound and no major congenital malformations were noted.   On 28-Sep-2018, the patient's mother underwent ultrasound, quad screen and no major congenital malformations were noted.  On an unspecified date, the fetus was exposed to Flucelvax QIVc [influenza vaccine, subunit influenza virus vaccine polyvalent, cell-culture-derived, route of administration: transplacental, batch number: 252664, dose, anatomical location and expiry date: not reported] (explicitly coded as fetal exposure during pregnancy) for an unknown indication.  On 16-Feb-2019, at gestational age of 39.1 weeks, the patient's mother delivered a male neonate by caesarean method. The neonate's birth weight was 4791 grams (explicitly coded as large for gestational age (LGA)), head circumference was 36.2 cm and body length were 55.9 cm. The appearance, pulse, grimace, activity, and respiration (APGAR) scores were 8 (at one minute), 8 (at five minutes) and there was no data for 10 minutes. There was no major congenital malformation noted. At the time of delivery, no pregnancy complications were reported.   The outcome of the event was unknown.   This case is linked to 201903660 (mother case).; Reporter's Comments: A male neonate patient experienced large for gestational age diagnosed at birth, unspecified period after maternal receipt of Flucelvax QIVc (considered as foetal exposure during pregnancy). The event large for gestational age lack onset latency. The known aetiologies includes genetic, increased maternal weight gain during pregnancy and maternal gestational diabetes. Considering the lack of biological evidence associated with suspect vaccine, the event large for gestational age, causality assessed as not related. The maternal BMI 29.0 is considered as known risk factor. The event foetal exposure during pregnancy assessed as not related considering the intended use of the vaccine. The case will be further assessed upon receipt of follow-up information. The company assessed the case as serious (medically significant).