Premature delivery at gestation age of 34.1 weeks; Anxiety; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 13-Jun-2019, concerning a 20-year-old, female pregnant subject of body weight: 172 lbs, height: 62 inches and body mass index (BMI) 31.5, enrolled in, a prospective observational safety study on pregnancy outcomes in women immunized with seasonal cell culture influenza trivalent (TIVc) or quadrivalent (QIVc) vaccine during pregnancy.  The subject's current conditions included nausea, high body mass index and polycystic ovarian syndrome (PCOS).  The subject's concomitant medications included Metformin ER (metformin hydrochloride) for polycystic ovarian syndrome (PCOS), Bonjesta (doxylamine succinate, pyridoxine hydrochloride) for nausea, TDAP vaccine (diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid) for vaccination and Prenatal vitamins (unspecified minerals and vitamins) as vitamins.  The subject's obstetrical history noted that the subject had no previous pregnancies. The subject had no maternal or paternal history with major congenital malformations. The subject did not have a prior history of use of tobacco, alcohol or illicit drugs during pregnancy.   The subject's last menstrual period (LMP) date was on 01-Nov-2018. The type of pregnancy was singleton. The subject's estimated delivery date (EDD) and corrected estimated delivery date (CEDD), were both reported as 08-Aug-2019.   On 27-Dec-2018, the subject underwent ultrasound screening and no major congenital malformations were noted.  On 31-Dec-2018, at approximately eight weeks of gestation (calculated per LMP), the subject was administered Flucelvax QIVc (Flu Vaccine Cell Subunit QIV NVD) [influenza vaccine, subunit influenza virus vaccine polyvalent, batch number: 252678, dose: 0.5 ml, route of administration, anatomical location and expiry date: not reported] (explicitly coded as Vaccine exposure during pregnancy') for influenza immunisation.  On 31-Jan-2019, the subject underwent on first trimester screen and nuchal translucency, and no major congenital malformations were noted.  On 28-Feb-2019, the subject underwent second trimester alpha 1 feto-protein and no major congenital malformations were noted.   On 13-Mar-2019, the subject underwent anatomy ultrasound screening and no major congenital malformations were noted.  On 03-May-2019, four months and three days after vaccination, the subject developed anxiety and started treatment with Lexapro (escitalopram oxalate), at a dose of 10 mg once a day, orally.  On, at 34.1 weeks of gestation (as reported), the subject delivered a live, female neonate by caesarean method. The neonate's birth weight was 2495 grams, while head circumference and body length were not reported. The appearance, pulse, grimace, activity, and respiration (APGAR) scores were 7 at one minute, 7 at five minutes and 9 for 10 minutes. There was no major congenital malformation identified at birth.   At the time of this report, the outcome of the event anxiety was not resolved (reported as ongoing).  The event of 'premature delivery' was considered serious due to criterion of medical significance, per company.   The reporter did not provide the causality assessment to Flucelvax QIV.  This case is linked to 201904503, the corresponding child report.  Follow up received on 23-Aug-2019 and process together on 31-Aug-2019 from other healthcare professional included: Pregnancy outcome was provided and accordingly, event of preterm delivery was added. Ultrasound on 27-Dec-2018 was added in patient tab. Indication and dose for vaccine were added. Case was linked with child case 201904503. Narrative was amended accordingly.  Follow up received from other health professional on 18-May-2020 included: The event premature delivery' was upgraded from non-serious to serious. The outcome of event anxiety' was confirmed to be not resolved (ongoing). Foetal outcome was changed from normal to perinatal complication. Narrative amended accordingly.   Company Comment: The subject experienced anxiety and premature delivery approximately five months after vaccination with the suspect product Flu Vaccine Cell Subunit QIV NVD (influenza vaccine). Chronology is unsuggestive. Causality was confounded by medical history of polycystic ovarian syndrome (PCOS) and therapy with concomitant medications Metformin ER (metformin hydrochloride), Bonjesta (doxylamine succinate, pyridoxine hydrochloride) and TDAP vaccine (diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid). Considering all the above mentioned, causal relationship between the suspect product and the events anxiety and premature delivery is assessed as unlikely related. (defaults to "related" in the safety database for reporting purposes) Vaccine exposure during pregnancy assessed as unrelated per company's conventions.; Sender's Comments: The subject experienced anxiety and premature delivery approximately five months after vaccination with the suspect product Flu Vaccine Cell Subunit QIV NVD (influenza vaccine). Chronology is unsuggestive. Causality was confounded by medical history of polycystic ovarian syndrome (PCOS) and therapy with concomitant medications Metformin ER (metformin hydrochloride), Bonjesta (doxylamine succinate, pyridoxine hydrochloride) and TDAP vaccine (diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid). Considering all the above mentioned, causal relationship between the suspect product and the events anxiety and premature delivery is assessed as unlikely related. (defaults to "related" in the safety database for reporting purposes) Vaccine exposure during pregnancy assessed as unrelated per company's conventions.