This is a serious clinical study case, initially received on 08-Nov-2018, concerning a 30-year-old adult female pregnant subject of body mass index 21.1, weight 136.8 lbs and height 67.5 inches 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/paternal history with major congenital malformations. The subject had no previous pregnancies reported. The subject did not have a prior history of use of tobacco, alcohol or illicit drugs during pregnancy. The subject's last lab report which included thyroid antibody test was normal. It was reported that the subject underwent thyroid antibody test every four weeks. The subject's last menstrual period date was 21-May-2018. The gestational age of the subject was 24 weeks (second trimester). The subject's current condition included increased thyroid antibodies which started on 08-Jul-2018. The subject's concomitant medication included levothyroxine for increased thyroid antibodies and Prenatal vitamins for pregnancy. On 28-Jul-2018, the subject underwent fibrosis mutation analysis and haemoglobin electrophoresis test and no major congenital malformation was noted. On 14-Aug-2018, the subject underwent first trimester screening and no major congenital malformation was noted. On 30-Sep-2018, the subject again underwent anatomical scan and no major congenital malformation was noted. On 06-Nov-2018, at approximately 24 weeks gestation, the pregnant subject was administered Flu Vaccine Egg Split QIV CSL (batch number: YF41708, dose, route of administration, anatomical location and expiry date: not reported) (explicitly coded as vaccine exposure during pregnancy) for an unknown indication. On 20-Dec-2018, the subject underwent 1-hour glucose tolerance test and no major congenital malformation was noted. On 04-Jan-2019, the subject underwent thyroid-stimulating hormone (TSH) test and no major congenital malformation was noted. On 22-Feb-2019, the subject had undergone ultrasound scan and moderate reduced fluid, foetal weight was less than 2 percent, small for gestational age (SGA) were noted and umbilical doppler was normal. No major congenital malformation was noted. At approximately 36.6 weeks gestation (preterm delivery), the subject gave a live birth to a female neonate by caesarean method. The characteristics of the neonate included birth weight: 2265 grams, head circumference: 30.5 cm, length: 47 cm and APGAR (appearance, pulse, grimace, activity, and respiration) scores were 4 at one minute and 9 at five minutes). The pregnancy complications included placental disruption and urgent caesarean section for concern of placental abruption. Heart rate was in 60s which was stimulated and positive pressure ventilation (PPV) was initiated which led to slow increase in heart rate to 100 after 2 minutes. The subject's expected date of delivery (EDD) was reported as 19-Mar-2019. This case is linked to 201902986 (baby case). Follow up received from the other health care professional on 30-Jan-2019: The subject's prenatal tests (1 Hour Glucose Tolerance Test, TSH Test) were added in relevant test section of patient tab. The narrative was amended accordingly. Follow up received from the other health care professional on 10-Apr-2019: The pregnancy outcome details (date of outcome of pregnancy: outcome: live birth, delivery method: caesarean) and foetal characteristics (gender: female, birth weight: 2265 grams, head circumference: 30.5 cm, body length: 47 cm, APGAR score: 4 at one minute and 9 at 5 minutes) were added in the patient tab. The subject's prenatal test (ultrasound scan) was added in the patient tab. The events premature delivery, abruptio placentae and ultrasound scan abnormal were added in the event tab. Hence, the classification 'special case with no AE' was removed in the general tab. The case was upgraded from non-serious to serious. The linking sentence was added in the narrative. The narrative and case comment were amended accordingly. Reporter's Comments: A 30-year-old pregnant subject with current condition (increased thyroid antibodies and concomitant medication levothyroxine) experienced placental abruption, 3 months 17 days after administration of study vaccine at 24 weeks gestation (coded to Exposure during pregnancy). At approximately 36.6 weeks gestation (preterm delivery), the subject gave a live birth to a female neonate by caesarean method. Considering the implausible temporal relationship between vaccination and reported event and lack of evidence for a biological mechanism that could cause the event, the event of abruptio placentae was assessed as not related to the study vaccine. Considering the implausible temporal relationship between vaccination and reported event, the event of preterm delivery appears more likely related to reported concern of abruptio placentae and was assessed as not related to 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).