Failure to progress and arrest of dilatation; Influenza; Pain in pelvis; Vomiting; Nausea; Dyspnea; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 25-Mar-2020, concerning a 26-year-old, pregnant, female subject of body weight: 219 lbs, height: 65 inches and body mass index (BMI): 36.4, enrolled in, a prospective observational safety study.  The subject's medical history included hypothyroidism, obesity/BMI 36.4, anxiety, attention deficit hyperactivity disorder, RhD negative and the subject was group B Streptococcus positive.  The subject's concomitant medications included Tdap (diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid) as vaccine, levothyroxine for hypothyroidism, vitamin b12 nos as vitamin, Prenatal vitamins (minerals nos; vitamins nos) as vitamin and Rhophylac (anti-d immunoglobulin) for RhD negative.  The subject's obstetrical history included one previous pregnancies with one spontaneous abortion. The subject had no history of offspring with major congenital malformation (MCM) and no relevant maternal history. The subject's paternal history included cousin with autism. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.   The subject's last menstrual period (LMP) date was 24-Jun-2019. The type of pregnancy was singleton. The subject's estimated delivery date (EDD) and corrected estimated date of delivery (CEDD) were reported as 30-Mar-2020.   On 16-Sep-2019, the subject underwent nuchal translucency and first trimester screen and no MCM was noted.   On 03-Oct-2019, approximately at 14 weeks of gestation (calculated per LMP), the subject was administered Flucelvax QIV (Flu Vaccine Cell Subunit QIV NVD) [influenza vaccine, subunit influenza virus vaccine polyvalent, batch number: 259809, dose: 0.5 ml, route of administration, anatomical location and expiration date: not reported] for an influenza immunization (explicitly coded as 'Vaccine exposure during pregnancy').  On 17-Oct-2019, the subject underwent MSAFP / serum markers test and second trimester screen and no MCM was noted.  On 05-Nov-2019, the subject underwent anatomy ultrasound scan and no MCM was noted.  On 04-Dec-2019, two months and one day after vaccination, the subject experienced dyspnoea.   On 31-Dec-2019, the subject underwent follow up ultrasound scan and no MCM was noted.  On 15-Feb-2020, four months and 12 days after vaccination, the subject experienced nausea and vomiting, and was treated with ondansetron at dose of 8 milligrams, orally, as needed.  On 24-Feb-2020, the subject underwent ultrasound scan and no MCM was noted.  On 27-Feb-2020, four months and 24 days after vaccination, the subject developed influenza and experienced pain in pelvis. The subject was treated with Macrobid (clarithromycin) at dose of 100 mg, every 12 hours, orally for pelvic pain and with Tamiflu (oseltamivir phosphate) at dose of one tablet orally, every day, for influenza.  On 06-Mar-2020, the subject finished her treatment with Macrobid (clarithromycin).  On 09-Mar-2020, the subject recovered from influenza and the treatment with Tamiflu (oseltamivir phosphate) was ended.    On 17-Mar-2020, five months 14 days after vaccination, delivery was complicated with arrest of dilation and failure to progress.   On the same day, at gestational age of 38.1 weeks (as reported), the subject gave birth via caesarean method to live, male neonate of birth weight 3997 grams. The neonate's head circumference and body length were not reported. The appearance, pulse, grimace, activity, and respiration (APGAR) score for one, five and ten minutes was not reported.   At the time of this report, the outcome of events pelvic pain, dyspnoea, vomiting and nausea was not resolved.   The outcome of arrested labour was not reported.   The events of arrested labour and influenza were considered serious due to the criterion of medical significance.   The reporter did not provide causality assessment.  Company comment: A pregnant subject was administered Flucelvax QIV and experienced influenza and pelvic pain 4 months 24 days after vaccination. The patient also developed arrested labour 5 months 14 days post vaccination, nausea and vomiting 4 months 12 days and dyspnoea 2 months 1 day. Chronology is unsuggestive for all events. The subject's medical history included hypothyroidism and obesity/BMI 36.4. Causality is highly confounded for dyspnoea, nausea and vomiting, since the patient was pregnant. However, causal role of vaccine is not excluded and is assessed as unlikely related for dyspnoea, nausea, vomiting and arrested labour (defaults to related for reporting purposes). Causality is possibly related for influenza and not related for pelvic pain. Vaccine exposure during pregnancy was assessed as not related per company's conventions.; Sender's Comments: A pregnant subject was administered Flucelvax QIV and experienced influenza and pelvic pain 4 months 24 days after vaccination. The patient also developed arrested labour 5 months 14 days post vaccination, nausea and vomiting 4 months 12 days and dyspnoea 2 months 1 day. Chronology is unsuggestive for all events. The subject's medical history included hypothyroidism and obesity/BMI 36.4. Causality is highly confounded for dyspnoea, nausea and vomiting, since the patient was pregnant. However, causal role of vaccine is not excluded and is assessed as unlikely related for dyspnoea, nausea, vomiting and arrested labour (defaults to related for reporting purposes). Causality is possibly related for influenza and not related for pelvic pain. Vaccine exposure during pregnancy was assessed as not related per company's conventions.