A2 gestational diabetes mellitus; Allergies; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 30-Jan-2020, concerning a 31-year-old pregnant, female subject of body weight 196 lbs, height 63 inches and body mass index (BMI) 34.7,  enrolled in, a prospective observational safety study.   The subject's medical history included history of gestational hypertension and gestational diabetes mellitus and high BMI.  The subject's concomitant medications included Prenatal vitamins (unspecified vitamins and minerals) for pregnancy.  The subject's obstetrical history noted four previous pregnancies which included one full term live birth and three spontaneous abortions. The subject did not have offspring with major congenital malformation (MCM), nor relevant maternal/paternal history with MCM.  The subject's last menstrual period (LMP) date was 03-Apr-2019. The type of pregnancy was singleton. The subject's estimated delivery date (EDD) was 08-Jan-2020 and corrected estimated delivery date (CEDD) was 13-Jan -2020. The subject did not consume alcohol, tobacco and illicit drugs during pregnancy.  On 02-Jul-2019, the subject underwent first sequential and nuchal translucency and no MCM was noted.  On 30-Jul-2019, the subject underwent second sequential and no MCM was noted.  On 29-Aug-2019, the subject underwent targeted ultrasound and no MCM was noted.  On 24-Oct-2019, the subject underwent growth on biophysical profile (BPP) ultrasound and no MCM was noted.  On 08-Nov-2019, at gestational age of 31 weeks, the subject was administered Afluria QIV (Flu Vaccine Egg Split QIV CSL) [influenza vaccine, batch number: P100112488, dose, route of administration, anatomical location and expiration date: not reported] for influenza immunisation (explicitly coded as 'Vaccine exposure during pregnancy').  On an unknown date, unknown amount of time after vaccination, the subject developed A2 (insulin requiring) gestational diabetes mellitus and allergies. Gestational diabetes mellitus was treated with glyburide at a dose of 2.5 mg every day via oral route of administration and with metformin at a dose of 1000 mg every day via oral route of administration. Allergies were treated with Claritin (loratadine) at a dose of 10 mg every day via oral route of administration. It was also reported that pregnancy status was collected and polyhydramnios was noted in fetus.  At the time of initial report, the outcome of A2 gestational diabetes mellitus and allergies was not reported.  The event of A2 gestational diabetes mellitus was considered serious due to the criterion of medical significance.  This reporter did not provide the causality assessment to Afluria QIV.  This case is linked to case 202001581 (the corresponding child case).  Company comment: The subject experienced gestational diabetes and hypersensitivity associated with the suspect product, Afluria QIV. Reportedly, vaccination occurred during pregnancy at gestational age of 31 weeks. Chronology is very unclear. Pregnant state may provide alternative aetiology for the events. Medical history of obesity (body mass index 34.7) and previous gestational hypertension and gestational diabetes mellitus may have contributed to development of the events. Vaccine exposure during pregnancy is assessed as not related per company's conventions. Limited and unclear reported information concerning the events gestational diabetes and hypersensitivity precludes thorough causality assessment, therefore causality for the events is unassessable.; Sender's Comments: The subject experienced gestational diabetes and hypersensitivity associated with the suspect product, Afluria QIV. Reportedly, vaccination occurred during pregnancy at gestational age of 31 weeks. Chronology is very unclear. Pregnant state may provide alternative aetiology for the events. Medical history of obesity (body mass index 34.7) and previous gestational hypertension and gestational diabetes mellitus may have contributed to development of the events. Vaccine exposure during pregnancy is assessed as not related per company's conventions. Limited and unclear reported information concerning the events gestational diabetes and hypersensitivity precludes thorough causality assessment, therefore causality for the events is unassessable.