Bilateral renal dilatation/pyelectasis; Vaccine fetal exposure during pregnancy; This is spontaneous case, initially received on 24-Jan-2020, concerning a fetus patient of unknown gender, whose mother was 21-year-old.   The mother's medical history included nausea, vaginal discharge and she was RhD negative.  The mother's concomitant medication included: Prenatal vitamins (unspecified vitamins and minerals) as vitamin supplementation, Diclegis (doxylamine succinate, pyridoxine hydrochloride) for nausea, TDAP vaccine [diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid], Rhophylac (anti-D immunoglobulin) as the mother was RhD negative and terconazole for vaginal discharge.  The patient's mother had no previous pregnancies. The patient's mother had no paternal family history of major congenital malformation (MCM), but she had autistic cousin in maternal family history. The mother did not use alcohol or illicit drugs during pregnancy, but she consumed cigarettes.  The mother's last menstrual period (LMP) date was 14-May-2019. The type of pregnancy was singleton. The mother's estimated delivery date (EDD) and corrected estimated date of delivery (CEDD) were both 18-Feb-2020. The father's age was 19.  On 17-Jul-2019, the patient's mother underwent dating ultrasound scan and no MCM was noted.  On 16-Aug-2019, the patient's mother underwent first trimester screen and nuchal translucency. No MCM was noted.  On 09-Sep-2019, the patient's mother underwent second trimester screen and maternal serum alpha-fetoprotein (MSAFP/serum markers). No MCM was noted.  On 25-Sep-2019, the patient's mother underwent ultrasound that was incomplete, so the result was unknown.  On 23-Oct-2019, approximately at 23 weeks of gestation, the patient's mother was administered Flucelvax QIV [influenza vaccine, subunit influenza virus vaccine polyvalent; batch number: 261223, dose: 0.5 ml, route of administration: intramuscular, anatomical location and expiration date: not reported] (explicitly coded as 'Foetal exposure during pregnancy') for an unknown indication. On the same day, the patient's mother underwent ultrasound and bilateral renal dilatation/pyelectasis was noted.  On 20-Nov-2019, 27-Nov-2019, 04-Dec-2019 and 18-Dec-2019, the patient's mother underwent ultrasound and bilateral renal dilatation/pyelectasis was noted.  At the time of this report, the outcome of bilateral renal dilatation/pyelectasis was not resolved.  The event of bilateral renal dilatation/pyelectasis was considered serious due to the criterion of medical significance.  The reporter did not provide causality assessment to Flucelvax QIV.  This case is linked to case 202001126 (the corresponding mother case).  Company comment: A foetus patient of unknown gender developed pyelocaliectasis after his mother has been exposed to Flucelvax QIV during pregnancy for an unknown indication. Chronology seems unsuggestive. Reportedly, on the same day of vaccination, the patient's mother underwent ultrasound and bilateral renal dilatation/pyelectasis was noted. The mother's medical history included nausea, vaginal discharge and she was RhD negative. The mother's concomitant medication included: Prenatal vitamins (unspecified vitamins and minerals) as vitamin supplementation, Diclegis (doxylamine succinate, pyridoxine hydrochloride) for nausea, TDAP vaccine [diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid], Rhophylac (anti-D immunoglobulin) as the mother was RhD negative and terconazole for vaginal discharge. The patient's mother had no previous pregnancies. The patient's mother had no paternal family history of major congenital malformation (MCM), but she had autistic cousin in maternal family history. The mother did not use alcohol or illicit drugs during pregnancy, but she consumed cigarettes. With information presented, causality is assessed as not related for both events due to implausible temporal relationship, company conventions and reported confounders.; Sender's Comments: A foetus patient of unknown gender developed pyelocaliectasis after his mother has been exposed to Flucelvax QIV during pregnancy for an unknown indication. Chronology seems unsuggestive. Reportedly, on the same day of vaccination, the patient's mother underwent ultrasound and bilateral renal dilatation/pyelectasis was noted. The mother's medical history included nausea, vaginal discharge and she was RhD negative. The mother's concomitant medication included: Prenatal vitamins (unspecified vitamins and minerals) as vitamin supplementation, Diclegis (doxylamine succinate, pyridoxine hydrochloride) for nausea, TDAP vaccine [diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid], Rhophylac (anti-D immunoglobulin) as the mother was RhD negative and terconazole for vaginal discharge. The patient's mother had no previous pregnancies. The patient's mother had no paternal family history of major congenital malformation (MCM), but she had autistic cousin in maternal family history. The mother did not use alcohol or illicit drugs during pregnancy, but she consumed cigarettes. With information presented, causality is assessed as not related for both events due to implausible temporal relationship, company conventions and reported confounders.