Delivery at 32.6 weeks of gestation; Prolonged premature rupture of membranes; Vaccine exposure during pregnancy; This observational study case, initially received on 07-Dec-2020 from other health professional and concerned a 31-year-old pregnant, female subject of body weight 146 lbs, height 63 inches and body mass index (BMI) 25.9,  enrolled in, a prospective observational safety study on pregnancy outcomes in women immunized with Afluria QIV, a seasonal quadrivalent vaccine, during pregnancy.   The subject's concurrent conditions included increased BMI. The subject's concomitant medications included Niferex (polysaccharide-iron complex) and Prenatal vitamins (unspecified minerals and vitamins) both used for pregnancy.  The subject's obstetrical history included no previous pregnancies. The subject had no history of offspring with major congenital malformation (MCM). Also, the subject had no maternal or paternal history with MCM. The subject did not use tobacco, alcohol or illicit drugs during pregnancy.  The subject's last menstrual period (LMP) date was reported as 07-Apr-2020. The subject's estimated delivery date (EDD) was not reported and corrected estimated date of delivery (CEDD) was reported as 12-Jan-2021. The type of pregnancy was singleton.   On 08-Jun-2020, the ultrasound revealed no MCM.  On 30-Jun-2020, ultrasound revealed no MCM, but first trimester screen revealed increased risk for Down's syndrome and no MCM.   On 12-Aug-2020, the ultrasound revealed no MCM.   On 27-Oct-2020, at approximately 29 weeks of gestation (calculated per LMP), the subject was vaccinated with Afluria QIV (Flu Vaccine Egg Split QIV CSL) (influenza vaccine, route of administration, anatomical location: not reported) (explicitly coded as 'Vaccine exposure during pregnancy') for an influenza immunisation. The batch number reported was P100265371.  On 11-Nov-2020, 15 days after receiving Afluria QIV, the subject developed prolonged premature rupture of membranes.  At gestational age of 32.6 weeks (as reported), the subject vaginally delivered a live birth, female neonate. The characteristics of the neonate included birth weight of 1984 grams, head circumference: 30 cm and length: 44.5 cm. Appearance, pulse, grimace, activity, and respiration (APGAR) scores were 8 (one minute) and 9 (five minutes). No data for APGAR score at 10 minutes was provided. No MCM was identified at birth.  On the same day, the subject recovered from prolonged premature rupture of membranes.   The outcome of 'premature delivery' was not reported.  The events of 'premature delivery' and 'premature rupture of membranes' were considered to be medically significant by a Physician within Seqirus' Pharmacovigilance and Risk Management Department.  The reporter did not provide causality assessment.  This case is linked to the case 202007591 (the corresponding baby case).  Company comment: A 31-year-old pregnant subject developed preterm premature rupture of membranes 15 days after vaccination with the suspect product, Afluria QIV. Reportedly, the event of premature delivery emerged 26 days post vaccination, at gestational age of 32.6 weeks. Chronology is unsuggestive. Underlying condition of body mass index high confounds causality for the events. With information presented, causality for both events is assessed as not related due to biological implausibility and presented confounder. Vaccine exposure during pregnancy is assessed as not related per company's conventions.; Sender's Comments: A 31-year-old pregnant subject developed preterm premature rupture of membranes 15 days after vaccination with the suspect product, Afluria QIV. Reportedly, the event of premature delivery emerged 26 days post vaccination, at gestational age of 32.6 weeks. Chronology is unsuggestive. Underlying condition of body mass index high confounds causality for the events. With information presented, causality for both events is assessed as not related due to biological implausibility and presented confounder. Vaccine exposure during pregnancy is assessed as not related per company's conventions.