Urinary tract infection; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 02-Jan-2020, concerning a 32-year-old female, pregnant subject of body weight 97 lbs, height 63 in and body mass index (BMI) 17.2, enrolled in a prospective observational safety study.  The subject's current medical history included the first occurrence of urinary tract infection and low BMI.   The subject's concomitant medications included: OB complete (pregnancy multivitamins and multiminerals) for healthy pregnancy and ampicillin for urinary tract infection.   The subject had two previous pregnancies which included one full term live birth and one spontaneous abortion. The subject had no history of offspring with major congenital malformation (MCM) and no maternal or paternal history with MCM. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.   The subject's last menstrual period (LMP) date was 22-May-2019. The subject's estimated date of delivery (EDD) was reported as 26-Feb-2020 and corrected EDD (CEDD) was not reported. The type of pregnancy was singleton.  On 21-Aug-2019, the subject underwent first trimester screen and cystic fibrosis mutation analysis and no MCM was noted.   On 09-Sep-2019, at approximately 15 weeks of gestation, the subject was administered Afluria QIV [influenza vaccine, batch number: P100110950, dose, expiration date, route of administration, anatomical location: not reported] (explicitly coded as 'Vaccine exposure during pregnancy') for influenza immunization. On the same day, the subject underwent second trimester screen and no MCM was noted.  On an unknown date in Dec-2019, the subject experienced the second occurence of urinary tract infection.  From 16-Dec-2019 to 23-Dec-2019, the subject was treated with ampicillin at dose of 500 mg, every day, orally.  At the time of initial reporting, the outcome for the second occurence of urinary tract infection was not reported.  The event of urinary tract infection was considered serious due to criterion of medical significance.  The causality assessment was not provided.  Company comment: A 32-year-old pregnant subject experienced urinary tract infection (UTI), associated with administration of Afluria QIV. The vaccine was administered at 15 weeks of gestation. Chronology is plausible. UTIs are common during pregnancy, because growing uterus makes pressure on the bladder and urinary tract. Although causality was highly confounded by subject's medical history of UTI, causal role of the suspect vaccine cannot be totally excluded and is assessed as unlikely related. Vaccine exposure during pregnancy assessed as unrelated per company's conventions.; Sender's Comments: A 32-year-old pregnant subject experienced urinary tract infection (UTI), associated with administration of Afluria QIV. The vaccine was administered at 15 weeks of gestation. Chronology is plausible. UTIs are common during pregnancy, because growing uterus makes pressure on the bladder and urinary tract. Although causality was highly confounded by subject's medical history of UTI, causal role of the suspect vaccine cannot be totally excluded and is assessed as unlikely related. Vaccine exposure during pregnancy assessed as unrelated per company's conventions.