Preterm delivery at 34 weeks of gestation; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 14-Jul-2020, concerning a 40-year-old pregnant, female subject of body weight 172.5 lbs, height 66.5 inches and body mass index (BMI) 27.4,  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 medical history included high body mass index and advanced maternal age.  The subject's concomitant medications included vitamin D3 as health supplement and Prenate Pixie- 10 mg Iron-1 mg-200 mg (as reported) for pregnancy.  The subject's obstetrical history included three previous pregnancy, two with full term live births and one elective abortion. The subject had no history of offspring with major congenital malformation (MCM). The subject had no maternal and paternal history with MCMs. The subject did not consume tobacco, alcohol and illicit-drugs during pregnancy.  The subject's last menstrual period (LMP) date was 29-Oct-2019. Type of pregnancy was multiple. The subject's estimated date of delivery (EDD) and corrected estimated date of delivery (CEDD) were reported as 04-Aug-2020.   On 20-Dec-2019, at approximately 7 weeks of gestation (calculated pet LMP), the subject was administered Afluria QIV (Flu Vaccine Egg Split QIV CSL) [influenza Vaccine; batch number: P100126099; dose, route of administration, anatomical location and expiry date: not reported] (explicitly coded as Vaccine exposure during pregnancy') for influenza immunisation.    On the same day, the subject underwent ultrasound scan, no MCM was noted.  On 03-Jan-2020, 18-Feb-2020, 17-Mar-2020 and 14-Apr-2020, the subject underwent ultrasound scan, no MCM was noted.  At gestational age of 34 weeks (as reported), the subject vaginally delivered first live female neonate and the second live male neonate. The characteristics of the first neonate included: birth weight of 2149 grams, head circumference: 31 cm, length: 48 cm and appearance, pulse, grimace, activity, and respiration (APGAR) scores were at one minute: 8, at five minutes: 9 and at ten minutes: not reported. The characteristics of the second neonate included: birth weight of 2381 grams, head circumference: 33 cm, length: 48 cm and appearance, pulse, grimace, activity, and respiration (APGAR) scores were at one minute: 7, at five minutes: 9 and at ten minutes: not reported. No MCMs were identified at birth for both neonates.  At the time of this report, the outcome for the event 'premature delivery' was not reported.  The event of premature delivery' was assessed as serious due to medically significant per the company.  The reporter did not provide causality assessment.  This case is linked to cases 202003881 and 202003882 (the corresponding child cases).  Company Comment: A 40-year-old pregnant subject was administered Afluria QIV at gestational age of 7 weeks. The subject experienced premature delivery of twins, six months after vaccination. Chronology is unsuggestive. Early-onset labour is frequent in twin pregnancies, which highly confound causality. Subject's medical history of high body mass index and advanced maternal age may have contributed to development of the event as well. Therefore, causal role of the suspect vaccine is assessed as not related. Vaccine exposure during pregnancy is assessed as unrelated per company's conventions.; Sender's Comments: A 40-year-old pregnant subject was administered Afluria QIV at gestational age of 7 weeks. The subject experienced premature delivery of twins, six months after vaccination. Chronology is unsuggestive. Early-onset labour is frequent in twin pregnancies, which highly confound causality. Subject's medical history of high body mass index and advanced maternal age may have contributed to development of the event as well. Therefore, causal role of the suspect vaccine is assessed as not related. Vaccine exposure during pregnancy is assessed as unrelated per company's conventions.