Delivery at 35.6 weeks of gestation; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 03-Apr-2020, concerning a 32-year-old, pregnant, female subject (Ethnicity: Not reported) of body weight: 227 lbs, height: 62 inches and body mass index (BMI): 41.5,  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 medical history included BMI increased, herpes simplex virus 1 & 2, chlamydia and anemia.  The subject's concomitant medications included ferrous sulfate for anemia, Zithromax (azithromycin) for chlamydia and Prenatal vitamins (unspecified vitamins and minerals) for pregnancy.   The subject's obstetrical history included three previous pregnancies, two full term live births and one spontaneous abortion. The subject had no history of offspring with major congenital malformation (MCM) and no relevant maternal and paternal medical history. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.   The subject's last menstrual period (LMP) date was 04-Jul-2019. The type of pregnancy was singleton. The subject's estimated delivery date (EDD) and corrected estimated date of delivery (CEDD) were reported as 09-Apr-2020.   On 28-Avg-2019, the subject underwent cystic fibrosis mutation analysis and spinal muscular atrophy and no MCMs were noted.   On 16-Sep-2019, the subject underwent ultrasound and no MCMs were noted.   On 30-Sep-2019, the subject underwent panorama and no MCMs were noted.   On 25-Oct-2019, approximately at 16 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: 261218, dose: 0.5 ml, route of administration, anatomical location and expiration date: not reported] (explicitly coded as 'Vaccine exposure during pregnancy') for an influenza immunization.  On 22-Nov-2019, the subject underwent ultrasound and no MCMs were noted.   On 31-Jan-2020, the subject underwent ultrasound and no MCMs were noted.   On the same day, the pregnancy status was collected, and pregnancy was complicated with intrauterine growth restriction in fetus.  On 14-Feb-2020, the subject underwent ultrasound and no MCMs were noted.   On 28-Feb-20120 the subject underwent ultrasound and no MCMs were noted.   On 01-Mar-20120 the subject underwent ultrasound and no MCMs were noted.   On Mar-2020, at gestational age of 35.6 weeks (as reported), the subject delivered a preterm live birth, female neonate by vaginal method. The neonate's birth weight was 1824 grams. The neonate's head circumference were 30.5 cm and body length were 44.5 cm. The appearance, pulse, grimace, activity, and respiration (APGAR) scores were 8 at one minute and 9 at five minutes. APGAR score for 10 minutes was not reported. No MCMs were identified at the time of birth.  At the time of this report, the outcome of event premature delivery' was not reported.  The event of premature delivery' was considered serious due to criterion of medical significance, per company.  The reporter did not provide causality assessment.   This case is linked to 202002747 (the corresponding baby case).  Company comment: A pregnant subject experienced premature delivery, 4 months and 13 days after receiving Flucelvax QIV. Chronology is unsuggestive. The subject's medical history included BMI increased, herpes simplex virus 1 & 2, chlamydia and anemia. However, causal role of the suspect vaccine cannot be excluded and is assessed as unlikely related (defaults to "related" in the safety database for reporting purposes). Vaccine exposure during pregnancy assessed as not related per company's conventions.; Sender's Comments: A pregnant subject experienced premature delivery, 4 months and 13 days after receiving Flucelvax QIV. Chronology is unsuggestive. The subject's medical history included BMI increased, herpes simplex virus 1 & 2, chlamydia and anemia. However, causal role of the suspect vaccine cannot be excluded and is assessed as unlikely related (defaults to "related" in the safety database for reporting purposes). Vaccine exposure during pregnancy assessed as not related per company's conventions.