Premature delivery; Vaccine exposure during pregnancy; This is a spontaneous case, initially received on 20-Nov-2019 from other health care professional, concerning a 25-year-old female, pregnant patient, of body weight 259.2 lbs, height 61 inches and body mass index (BMI) 41.8.   The patient's current medical history included pregnancy induced hypertension and high BMI.  The patient's concomitant medications included labetalol for pregnancy induced hypertension and included prenatal vitamins (unspecified vitamins and minerals) for neonatal care (as reported).  The patient's obstetrical history included one previous pregnancy with no birth defects. The patient had no history of offspring with major congenital malformation (MCM). Also, the patient had no maternal or paternal history with MCM. The patient did not use tobacco, alcohol or illicit drugs during pregnancy.   The patient's last menstrual period (LMP) date was 18-Jan-2019. The patient's estimated date of delivery (EDD) was reported as 25-Oct-2019 and corrected estimated date of delivery (CEDD) was reported as 29-Oct-2019. Type of pregnancy was multiple.  On 14-Mar-2019, the patient underwent ultrasound and no MCM was noted.  On 02-Apr-2019, the patient underwent first trimester screening and no MCM was noted.  On 17-Jun-2019, the patient underwent ultrasound and no MCM was noted.  At approximately 35 weeks of gestation, the patient was administered Flucelvax QIV [Influenza vaccine, subunit influenza virus vaccine polyvalent; batch number: 261207, dose, route of administration, anatomical location and expiration date: not reported] (explicitly coded as 'Vaccine exposure during pregnancy') for an unknown indication.  At gestational age of 36.1 weeks, the patient vaginally delivered the first premature live female neonate and with vacuum assistance the second live female neonate. The characteristics of the first neonate included: birth weight 2345 grams, head circumference: not reported, length: 45.7 cm and appearance, pulse, grimace, activity, and respiration (APGAR) scores were 8 (one minute) and 9 (five minutes). The characteristics of the second neonate included: birth weight 2905 grams, head circumference: not reported, length: 50.80 cm and appearance, pulse, grimace, activity, and respiration (APGAR) scores were 7 (one minute) and 9 (five minutes). There was no APGAR score data for 10 minutes reported for both neonates. No MCMs were identified at birth.  The case was assessed as serious (medically significant).  The reporter did not provide causality assessment.  This case is linked to cases 201906224 and 201906225 (the corresponding child cases).  Company Comment: The patient experienced premature delivery after vaccination with the suspect product, Flucelvax QIV. Reportedly, vaccination occurred during pregnancy at 35 weeks of gestation. Chronology is possible. Medical history of obesity (body mass index 41.8) and twin pregnancy may provide more plausible alternative aetiology for the event premature delivery. Pregnancy induced hypertension and concomitant medication, labetalol may have also contributed to development of the event. Vaccine exposure during pregnancy is assessed as not related per company's conventions. For the event premature delivery, causal role of the suspect product cannot be totally excluded and is assessed as unlikely related.; Sender's Comments: The patient experienced premature delivery after vaccination with the suspect product, Flucelvax QIV. Reportedly, vaccination occurred during pregnancy at 35 weeks of gestation. Chronology is possible. Medical history of obesity (body mass index 41.8) and twin pregnancy may provide more plausible alternative aetiology for the event premature delivery. Pregnancy induced hypertension and concomitant medication, labetalol may have also contributed to development of the event. Vaccine exposure during pregnancy is assessed as not related per company's conventions. For the event premature delivery, causal role of the suspect product cannot be totally excluded and is assessed as unlikely related.