Increased risk of trisomy 21/Risk of trisomy 21/ Trisomy 21 noted on 1st trimester screen; Risk of trisomy 21 associated with 1st trimester screen; Vaccine exposure during pregnancy; This is a serious spontaneous case, initially received on 13-Jun-2019, concerning a 26-year-old, adult, female pregnant patient, body weight: 139 lbs, height 52 inches and body mass index (BMI): 25.4.   The patient was non-immune to rubella (reported as rebella non-immune). The patient had one previous pregnancy that was full term live birth and no birth defects were reported. The patient had no maternal or paternal history with major congenital malformations. The patient had no history of offspring with major congenital malformations.  The concurrent medical condition of the patient during this pregnancy included nausea. The concomitant medications of the patient included Diclegis (doxylamine succinate, pyridoxine hydrochloride) for nausea, Prenatal vitamins (minerals nos, vitamins nos) as vitamins and TDAP (diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid) as vaccination.  The patient's last menstrual period (LMP) date was on an unknown date in 2018. The type of pregnancy was singleton. The patient did not use tobacco, alcohol or illicit drugs during current pregnancy.   On an unknown date, the pregnancy status of the patient was collected, and no pregnancy complications were noted during current pregnancy.  On 06-Nov-2018, the patient was administered Flucelvax QIVc [influenza vaccine, subunit influenza virus vaccine polyvalent, cell cultured derived, dose, 0.5 ml (reported as 0.5 mg), frequency: 1, route of administration: intramuscular, batch number: 252226, anatomical location and expiry date: not reported] (explicitly coded as vaccine exposure during pregnancy) as vaccination.  On the same day, the subject underwent initial ultrasound and no major congenital malformation was noted.  On 11-Dec-2018, 1 month and 5 days after vaccination, the subject underwent 1st trimester screening that showed increased risk of Trisomy 21 (prenatal screening test abnormal) and no major congenital malformation was noted. On the same day, the subject also underwent Nuchal translucency (NT) ultrasound and no major congenital malformation was noted.  On 17-Dec-2018, the subject underwent Maternit 21 (as reported) with no major congenital malformation noted and there was no increased risk of Trisomy 21.  On 11-Jan-2019, the subject underwent second trimester screening, alphafoetoprotein (AFP) test and no major congenital malformation was noted.   The outcome of the event risk of trisomy 21 was recovered on 17-Dec-2018.  The patient's estimated date of delivery (EDD) and corrected estimated date of delivery (CEDD), both were reported as 24-Jun-2019.; Reporter's Comments: A 26-year-old pregnant patient was found to have increased risk for trisomy 21 on ultrasound, more than one month after vaccination with Flucelvax QIVc. Considering genetic aetiology of the event, the causality was assessed as not related to suspect vaccine due to biological implausibility. The event vaccine exposure during pregnancy was assessed as not related to suspect vaccine due to intended use of the product.  The company assessed this case as serious (medically significant).