Preterm delivery at 36.9 weeks of gestation; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 11-Feb-2020, concerning a 20-year-old, pregnant, female subject of height 63 inches, weight and body mass index (BMI): not reported, enrolled in a prospective observational safety study.  The subject's relevant medical history was not reported.  The subject's concomitant medications included Prenatal vitamins (unspecified vitamins and minerals) for pregnancy.  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 (MCMs). The subject had no history of offspring with MCMs. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.  The subject's last menstrual period (LMP) date was 26-Mar-2019, the estimated delivery date (EDD) was reported as 31-Dec-2019, while the corrected delivery date (CEDD) was not reported. The type of pregnancy was multiple (twin pregnancy).  On 06-Nov-2019, 13-Nov-2019 and 20-Nov-2019, the subject underwent non-stress test and no MCMs were noted.  On 27-Nov-2019, the subject underwent ultrasound and no MCMs were noted.  On 04-Dec-2019, the subject underwent ultrasound and non-stress test. No MCMs were noted.  On 21-Oct-2019, at gestational age at 29 weeks, the subject was administered Flucelvax QIV (Flu Vaccine Cell Subunit QIV NVD) [influenza vaccine; batch number: 261218, dose: 0,5 ml, anatomical location, route of administration and expiration date: not reported] (explicitly coded as Vaccine exposure during pregnancy') for influenza immunisation.   At approximately 36,9 weeks of gestation, the subject delivered two premature live female and male neonates by caesarean method. The characteristics of the female neonate included birth weight: 2750 g, head circumference: 34.3 cm and length: 48.3 cm. The appearance, pulse, grimace, activity, and respiration (APGAR) scores were 8 (one minute) and 9 (five minutes). The characteristics of the male neonate included: birth weight: 2885 g, head circumference: 34.3 cm and length: 48.3 cm. APGAR scores were 8 (one minute) and 9 (five minutes). The APGAR score for ten minutes was not reported for both neonates. No major congenital malformations (MCMs) were identified at the time of birth, and no pregnancy complications were noted.  At the time of this report, the outcome of the event 'premature delivery' was not reported.  The event of 'premature delivery' was assessed as serious due to criteria of medically significant, per company.   The reporter did not provide causality assessment.  This case is linked to cases 202001704 and 202001705, the corresponding child cases.  Company comment: Reportedly, premature delivery was associated with Flucelvax QIVc. Vaccine was administered at 29 weeks of gestation. Temporal relationship is plausible. More information regarding medical history is needed. With information available, 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 is assessed as unrelated per company's conventions.; Sender's Comments: Reportedly, premature delivery was associated with Flucelvax QIVc. Vaccine was administered at 29 weeks of gestation. Temporal relationship is plausible. More information regarding medical history is needed. With information available, 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 is assessed as unrelated per company's conventions.