Gestational diabetes; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 31-Oct-2019, concerning a 30-year-old, pregnant, female subject of body weight: 125 lbs, height: 64 inches and body mass index (BMI): 21.5, enrolled in, a prospective observational study.  The subject's past medical history included ventricular septal defect at birth. Ventricular septal defect repair was performed in 1989, while residual muscle mass was removed in 2010.   In Sep-2018 the subject underwent echocardiogram and results were normal.   The subject's concomitant medication included prenatal vitamin (unspecified minerals and vitamins) for pregnancy.   The subject's obstetrical history included no previous pregnancies. Also, the subject had no maternal or paternal history with major congenital malformations (MCMs). The subject did not use tobacco, alcohol or illicit drugs during pregnancy.  The subject's last menstrual period (LMP) date was 12-May-2019, the estimated delivery date (EDD) was 16-Feb-2019 and corrected estimated date of delivery (CEDD) was reported as 23-Feb-2020. The type of pregnancy was singleton.   On 13-Aug-2019, the subject underwent MaterniT21 prenatal test and no major MCM was noted.  On 07-Oct-2019, at gestational age of 21 weeks, the subject was administered Afluria Quadrivalent (Flu Vaccine Egg Split QIV CSL) [influenza vaccine; batch number: P100112488, dose, route of administration, anatomical location and expiry date: not reported] (explicitly coded as 'Vaccine exposure during pregnancy') for an influenza immunisation.   On the same date, the subject underwent targeted ultrasound scan and choroid plexus cyst, bilateral and small placental cyst were noted. No MCM was noted.  On 22-Nov-2019, the subject underwent repeated ultrasound and it was reported that choroid plexus cyst, bilateral was resolving, while small placental cyst was stable. No MCM was noted. Ultrasound would be repeated in four weeks.  On 10-Dec-2019, the subject developed pregnancy complication gestational diabetes.   At the time of follow up report, the outcome of the event gestational diabetes was not reported.   The event of gestational hypertension was assessed as serious due to the criterion of medical significance (IME event).   The reporter did not provide causality assessment to Afluria Quadrivalent.   This case is linked to 201905852, the corresponding baby case.  Follow up information received from other health professional on 12-Dec-2019: Subject's medial history and laboratory data updated. Dosage regimen details provided for prenatal vitamins. Narrative was amended accordingly.  Follow up information received from other health professional on 27-Jan-2019: Event of gestational diabetes added. Narrative was amended accordingly.  Company comment: A 30-year-old pregnant female subject developed gestational diabetes after vaccination with the suspect product Flu Vaccine Egg Split QIV CSL for an unknown indication. Chronology seems plausible. The subject's past medical history included ventricular septal defect at birth. Ventricular septal defect repair was performed in 1989, while residual muscle mass was removed in 2010. The subject's concomitant medication included prenatal vitamin (unspecified minerals and vitamins) for pregnancy. Reportedly, BMI of the subject was 21.5 (which is in normal, referent range). Gestational diabetes is caused by not enough insulin in the setting of insulin resistance. Risk factors include being overweight, previously having gestational diabetes, a family history of type 2 diabetes, and having polycystic ovarian syndrome. Additional risk factors include: maternal age  a woman's risk factor increases as she gets older (especially for women over 35 years of age), paternal age  one study found that a father's age over 55 years was associated with GD and ethnicity. With information presented causality for gestational diabetes is assessed as possibly related while for exposure during pregnancy is assessed as not related per company conventions.; Sender's Comments: A 30-year-old pregnant female subject developed gestational diabetes after vaccination with the suspect product Flu Vaccine Egg Split QIV CSL for an unknown indication. Chronology seems plausible. The subject's past medical history included ventricular septal defect at birth. Ventricular septal defect repair was performed in 1989, while residual muscle mass was removed in 2010. The subject's concomitant medication included prenatal vitamin (unspecified minerals and vitamins) for pregnancy. Reportedly, BMI of the subject was 21.5 (which is in normal, referent range). Gestational diabetes is caused by not enough insulin in the setting of insulin resistance. Risk factors include being overweight, previously having gestational diabetes, a family history of type 2 diabetes, and having polycystic ovarian syndrome. Additional risk factors include: maternal age  a woman's risk factor increases as she gets older (especially for women over 35 years of age), paternal age  one study found that a father's age over 55 years was associated with GD and ethnicity. With information presented causality for gestational diabetes is assessed as possibly related while for exposure during pregnancy is assessed as not related per company conventions.