Premature delivery; Vaccine exposure during pregnancy; This is a serious observational study case initially received on 01-Oct-2019, concerning a 19-year-old adult female, pregnant subject of body weight 157 lbs, height 67 inches and body mass index (BMI) 24.6, enrolled in a prospective observational safety study.  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 (MCM). The subject did not use tobacco, alcohol or illicit drugs during pregnancy.   The subject's last menstrual period (LMP) date was 21-Apr-2018. The subject's estimated date of delivery (EDD) and corrected estimated date of delivery (CEDD) were reported as 26-Jan-2019. The type of pregnancy was singleton.   The subject's historical medical conditions included chlamydia, bacterial vaginosis and yeast. The subject's current medical condition included anaemia. The subject's historical drugs included Zithromax (azithromycin) for chlamydia, Flagyl (metronidazole) for bacterial vaginosis and Terazol (terconazole) for yeast. The subject's concomitant medication included prenatal vitamins (minerals nos, vitamins nos) for pregnancy and ferrous sulphate for anaemia.  On 11-May-2018, the subject underwent cystic fibrosis mutation analysis and spinal muscular atrophy. No MCM was noted.  On 04-Jun-2018, the subject underwent ultrasound scan and no MCM was noted.   On 16-Jul-2018, the subject underwent Quad screen and ultrasound scan. No MCM was noted.  On 08-Oct-2018, at approximately 24 weeks of gestation, the subject was administered Flu Vaccine Cell Subunit QIV NVD [influenza vaccine, subunit influenza virus vaccine polyvalent, dose: 0.5 mL, batch number: 252664, route of administration, anatomical location and expiration date: not reported] (explicitly coded as vaccine exposure during pregnancy) for an influenza immunisation.  On 15-Oct-2018, ultrasound was performed, and no MCM was noted.  On 24-Oct-2018, the subject underwent non-stress test and no MCM was noted.  On 15-Nov-2018, the subject underwent ultrasound scan and no MCM was noted.  At gestational age of 35.9 weeks, the subject vaginally delivered a live birth, female neonate. The characteristics of the neonate included birth weight: 2977 grams, head circumference: 33.7 cm and length: 48.9 cm. Appearance, pulse, grimace, activity, and respiration (APGAR) scores were 8 (one minute) and 9 (five minutes). There was no APGAR score data for 10 minutes. No pregnancy complications were noted and no MCMs were identified at birth.  This case is linked to case number 201904967 (corresponding child case).; Sender's Comments: The subject experienced premature delivery after vaccination with the suspect product Flu Vaccine Cell Subunit QIV NVD. Reportedly, vaccination occurred during pregnancy. Chronology is plausible. Medical history of anaemia and concomitant medication ferrous sulphate may have contributed to development of the event. Causal relationship between the suspect product and exposure during pregnancy is assessed as not related per company conventions. Considering all the above mentioned, causal relationship between the suspect product and the events is assessed as unlikely related.