This is a serious observational study case initially received on 31-Oct-2018, concerning a 27-year-old, pregnant female subject of body weight: 264 lbs and height: 63 inches and body mass index (BMI): 46.8, enrolled in a prospective observational safety study. The subject did not have any history of offspring with major congenital malformation. Also, the subject had no maternal or paternal history with major congenital malformations. The subject's obstetrical history included 4 previous pregnancies with 2 previous spontaneous abortions and 2 full term live births. The father did not receive any medications prior to conception. The subject did not have a prior history of use of tobacco, alcohol or illicit drugs during pregnancy. The subject's current conditions included severe pre-eclampsia, gestational hypertension and polycystic ovarian syndrome and the concomitant medications included Aspirin for severe pre-eclampsia. The subject's last menstrual period (LMP) date was 09-Mar-2018. The type of pregnancy was singleton. The gestational age of the subject was 32 weeks. On 13-Aug-2018, the subject underwent targeted ultrasound and no major congenital malformation was noted. On 18-Oct-2018, the pregnant subject was administered Flu Vaccine Egg Split QIV CSL (batch number: YF40208, dose, route of administration, expiry date and anatomical location: not reported) (explicitly coded as vaccine exposure during pregnancy) for an unknown indication. At 35.7-week gestational age, the subject gave birth to a female infant (reported as preterm delivery). The delivery method was caesarean. Infant body weight was 3884 grams and the appearance, pulse, grimace, activity, and respiration (Apgar) score: 8 at minute 1 and 9 at minute 5. The subject's estimated date of delivery (EDD) was reported as 29-Dec-2018. This case was linked to case: 201903006 (baby case). Follow-up received from other health professional on 10-Apr-2019: Details regarding pregnancy outcome was added in the patient tab. Details regarding the indication and regimen of the concomitant medication Aspirin was added in the product tab. The event pre-eclampsia, gestational hypertension and polycystic ovarian syndrome were deleted from the event tab and captured as current conditions under relevant history in the patient tab. The event premature delivery was added in the event tab. At 35.7-week gestational age, the subject gave birth to a female infant (reported as preterm delivery). The delivery method was caesarean. Infant weight was 3884 grams and the appearance, pulse, grimace, activity, and respiration (Apgar) score: 8 at minute 1 and 9 at minute 5. The narrative and case comment were amended accordingly.; Reporter's Comments: A 27-year-old female pregnant subject with gestational history (2 previous spontaneous abortions and 2 full term live births) was administered Flu Vaccine Egg Split QIV CSL at 32 weeks of gestation (explicitly considered as exposure during pregnancy). The pregnancy status of the subject was collected, and history of pre-eclampsia, gestational hypertension and polycystic ovarian syndrome were noted. At 35.7-week gestational age, the subject gave birth to a female infant (reported as preterm delivery) by caesarean section 1 month 11 days post vaccination. Considering the risk factors (gestational history, pre-eclampsia, gestational hypertension and polycystic ovarian syndrome) and no evidence for a biological mechanism that could cause the event, the event of premature delivery was assessed as not related to the study vaccine. The decision to administer a vaccine during pregnancy is related to medical decision making by the mother and her physician and is not related to any property of the medication. The event of exposure during pregnancy was assessed as not related considering the intended use of the vaccine. The company assessed the case as serious (medically significant).