Foetal exposure during pregnancy; Pre-term birth at 36.7 weeks of gestation; This is an observational study case, initially received on 25-Feb-2021 from other health professional and concerned a female neonate, whose mother was a 33-year-old, female, pregnant subject of body weight: 148 lbs, height: 62 inches and body mass index (BMI): 27.1, enrolled in, a prospective observational study.  The maternal concurrent condition included BMI high. The maternal past medical history included bacterial vaginosis. The maternal concomitant medications included OB complete one (fish oil, doconexent, icosapent, calcium ascorbate, cholecalciferol, alpha-tocopherol acetate, D-thiamine mononitrate, riboflavin, niacinamide, pyridoxine hydrochloride, folic acid, cyanocobalamin, biotin, calcium threonate, calcium malate, calcium carbonate, iron, ferrous asparto glycinate, potassium iodide, magnesium oxide, zinc oxide, and cupric sulfate capsule, liquid filled) for healthy pregnancy and terconazole used for bacterial vaginosis.  The maternal past medications included Metrogel (metronidazole) used for bacterial vaginosis.  The maternal obstetrical history included two previous pregnancies with one full term live birth, and one spontaneous abortion. The neonate's mother had no history of offspring with major congenital malformation (MCM). The neonate's mother had no relevant maternal and paternal medical history with MCM. The neonate's mother did not use tobacco, alcohol or illicit drugs during pregnancy.  The maternal last menstrual period (LMP) date was on 13-Apr-2020, the estimated delivery date (EDD) was reported as 18-Jan-2021 and corrected estimated date of delivery (CEDD) was not reported. The type of pregnancy was singleton.  On 06-Jul-2020, first trimester screen revealed no MCMs.  On 27-Jul-2020, second trimester screen revealed increased risk of Down syndrome, but no MCM was noted.   On 06-Aug-2020, amniocentesis revealed no MCMs.  On 07-Aug-2020, amniocentesis revealed no MCMs. The whole genome chromosome single-nucleotide polymorphism (SNP) microarray analysis was normal. No significant deoxyribonucleic acid (DNA) copy number changes or copy neutral regions within the 2.695 million region specific SNP.  On 04-Sep-2020, approximately at 20 weeks of gestation (calculated per LMP), the neonate's mother was vaccinated with Afluria Quadrivalent  (Flu Vaccine Egg Split QIV) (influenza vaccine; dose, route of administration and anatomical location: not reported) (explicitly coded as 'Foetal exposure during pregnancy') for influenza immunisation. The batch number reported was P100239705.  On an unknown date in 2020, an unknown amount of time after receiving Afluria Quadrivalent, the neonate's mother developed bacterial vaginosis.  On 02-Oct-2020, the neonate's mother started therapy with Metrogel 0.75 % cream (metronidazole), once at night, vaginally for bacterial vaginosis.  On 07-Oct-2020, the neonate's mother stopped treatment with Metrogel.  At 36.7 weeks of gestation (as reported), the mother delivered live birth, female neonate via vaginal method of delivery. The neonate's birth weight was 2745 g, body length was reported as 47.6 cm, head circumference was reported as 33.5 cm. Appearance, pulse, grimace, activity and respiration (APGAR) scores at one minute was 9, at five minutes was 9 and at ten minutes was not reported. There were no MCMs identified at birth.  The outcome of event 'premature birth' was not reported.   The reporter did not provide a causality assessment.  The event 'premature birth' was considered to be medically significant by a Physician within Seqirus's Pharmacovigilance and Risk Management Department.   The case is linked to 202007444, the corresponding mother case.  Company comment: A female neonate was exposed to the suspect product, Afluria Quadrivalent. The neonate's mother was vaccinated with Afluria Quadrivalent at approximately 20 weeks of gestation. The neonate experienced premature birth at 36.7 weeks of gestation (3 months and 22 days after vaccination). The maternal concurrent condition included BMI high. The maternal past medical history included bacterial vaginosis. The maternal obstetrical history included two previous pregnancies with one full term live birth, and one spontaneous abortion. Causal role of the suspect vaccine is assessed as not related. Foetal exposure during pregnancy is assessed as not related per company's conventions.; Sender's Comments: A female neonate was exposed to the suspect product, Afluria Quadrivalent. The neonate's mother was vaccinated with Afluria Quadrivalent at approximately 20 weeks of gestation. The neonate experienced premature birth at 36.7 weeks of gestation (3 months and 22 days after vaccination). The maternal concurrent condition included BMI high. The maternal past medical history included bacterial vaginosis. The maternal obstetrical history included two previous pregnancies with one full term live birth, and one spontaneous abortion. Causal role of the suspect vaccine is assessed as not related. Foetal exposure during pregnancy is assessed as not related per company's conventions.