Pre-term labor at 28.3 weeks of gestation resulting in birth; Syphilis; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 24-Mar-2020, concerning a 28-year-old, female pregnant subject of body weight: 132 lbs, height: 67 inches and body mass index (BMI): 20.7  enrolled in a prospective observational safety study. The subject's medical history was not provided.  The subject's concomitant medications included Prenatal vitamins (minerals not otherwise specified (nos); vitamins nos) for pregnancy.  The subject's obstetrical history noted that subject had four previous pregnancies with one full term live birth, one elective abortion and two spontaneous abortions. The subject had no history of offspring with major congenital malformation (MCM). The subject had no relevant maternal and paternal medical history. The subject did not use tobacco, illicit drug or alcohol during pregnancy.  The subject's last menstrual period (LMP) date was reported as 15-Apr-2019. The subject's estimated delivery date (EDD) and corrected estimated date of delivery (CEDD) were reported as 04-Feb-2020. The type of pregnancy was singleton.   On 18-Jun-2019, the subject underwent cystic fibrosis mutation analysis and spinal muscular atrophy test and no MCM was noted.  On 21-Aug-2019, the subject underwent panorama test and no MCM was noted.  On 19-Sep-2019, the subject underwent ultrasound and no MCM was noted.  On 17-Oct-2019, at approximately 26 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; dose: 0.5 ml, batch number: 262218, anatomical location, route of administration and expiration date: not reported] (explicitly coded as Vaccine exposure during pregnancy') for influenza immunisation.   At gestational age of 28.3 weeks (reported as), the subject delivered live birth, female neonate via caesarean method of delivery. The neonate's birth weight was reported as 97 g, her head circumference and length were not provided. The appearance, pulse, grimace, activity, and respiration (APGAR) scores were 1 (one minute), 4 (five minutes) and 7 (ten minutes). No MCM was noted on delivery. On the same day, the subject underwent ultrasound and no MCM was noted.   On the same day, the subject developed syphilis and was treated with penicillin, 1 g, intramuscularly, administered once. On the same day, the subject recovered from the event syphilis.  At the time of this report, the outcome of the event premature labor' was not reported.  The events of syphilis and preterm labour were assessed as serious, due to criterion of medical significance, per company.   The reporter did not provide causality assessment.  The case is linked to 202002612, the corresponding child case.  Company comment: A pregnant subject developed premature labour 28 days after vaccination with the suspect product Flucelvax QIVc. On date of delivery, the patient was diagnosed with syphilis and was treated with penicillin. Reportedly, on the same day, the subject recovered from the event syphilis. Chronology is plausible for premature labour. With information presented, for the event of syphilis causality is assessed as not related to the product due to pathophysiological implausibility. Premature labour is assessed as unlikely related (defaults to related for reporting purposes). Vaccine exposure during pregnancy is considered not related per company conventions.; Sender's Comments: A pregnant subject developed premature labour 28 days after vaccination with the suspect product Flucelvax QIVc. On date of delivery, the patient was diagnosed with syphilis and was treated with penicillin. Reportedly, on the same day, the subject recovered from the event syphilis. Chronology is plausible for premature labour. With information presented, for the event of syphilis causality is assessed as not related to the product due to pathophysiological implausibility. Premature labour is assessed as unlikely related (defaults to related for reporting purposes). Vaccine exposure during pregnancy is considered not related per company conventions.