This is a serious observational study case, initially received from other health professional on 26-Feb-2019, concerning a 32-year-old, adult female pregnant subject of body weight: 135 lbs, height: 65 inches and body mass index (BMI): 22.5 enrolled in a safety study on pregnancy outcomes in women immunized with seasonal cell culture influenza trivalent (TIVc) or quadrivalent (QIVc) vaccine during pregnancy. The subject had no maternal and paternal history of major congenital malformations. The subject had no history of offspring with major congenital malformations. The subject had 1 previous pregnancy which was a pre-term live birth with no birth defects reported. The subject did not use tobacco, alcohol or illicit drugs during pregnancy. The subject's last menstrual period (LMP) date was 01-Jun-2018. The type of pregnancy was singleton. The subject's current condition included panic attacks since an unspecified date. On 05-Jul-2018, the subject experienced spotting (Rh blood type) and was treated with Rhogam (immunoglobulin; stopped on the same day). On the same day, the subject had undergone cystic fibrosis mutation analysis and no major congenital malformation was noted. The subject was given Prenatal vitamins (minerals nos, vitamins nos) 1 tablet for pregnancy (from 05-Jul-2018 an was ongoing). On 12-Jul-2018, the subject experienced candidiasis and was treated with Diflucan 150 mg, oral (on 12-Jul-2018). The subject experienced nausea (from 12-Jul-2018 to 09-Nov-2018) and took promethazine 25 mg, oral for nausea (12-Jul-2018 to 09-Nov-2018). On 23-Jul-2018 and 23-Aug-2018, the subject had undergone ultrasound scan and subchorionic haemorrhage was noted. On 21-Sep-2018, the subject had undergone ultrasound scan again, maternal serum alpha-fetoprotein (MSAFP)/ serum markers analysis and quadruple screening and no major congenital malformation was noted. On 25-Oct-2018, at gestational age of 21 weeks, the subject was administered Flu Vaccine Cell Subunit QIV NVD (influenza vaccine, subunit influenza virus vaccine polyvalent, batch number: 252664, dose, route of administration, anatomical location and expiry date: not reported) (explicitly coded as vaccine exposure during pregnancy) for an unknown indication. On the same day after vaccination, the subject experienced preterm labor. The subject was treated with Makena of dose: 1.1 cc/ml, subcutaneously every week (qw) [from 25-Oct-2018 to 08-Feb-2018]. On 09-Nov-2018, nausea was resolved and the treatment drug promethazine for nausea was stopped. On 21-Nov-2018, 27 days after vaccination, the subject experienced anaemia and on the same day, the subject began to use ferrous sulfate of dose: 325 mg, once a day (qd) orally (from 21-Nov-2018 and was ongoing). On 19-Dec-2018, at the gestational age of 28.4 weeks, the subject was administered a concomitant vaccine TDAP (diphtheria vaccine toxoid, pertussis vaccine acellular, tetanus vaccine toxoid, dose: reported as 1, route of administration: intramuscular, frequency: once, anatomical location, batch number and expiry date: not reported) for immunization. On 17-Jan-2019 and on 07-Feb-2019, the subject had undergone ultrasound screening and no major congenital malformation was noted. The event preterm labor resolved on 08-Feb-2019, while event anaemia had not resolved. 3 months and 26 days after vaccination, at the gestational age of 37.4 weeks, the subject gave live birth to a female infant of body weight: 3160 grams, head circumference: 33.7 cm and body length: 50.8 cm by vaginal method. The APGAR score was 9 at one minute, 9 at five minutes and there was no data for 10 minutes. At the time of delivery, no pregnancy complications were reported and at the time of birth, no major congenital malformations were noted. The subject's estimated delivery date (EDD) was 10-Mar-2019. The outcome of the event anaemia was not recovered.; Reporter's Comments: A 32-year-old pregnant subject with a history of preterm live birth experienced preterm labor, on the same day after administration of study vaccine at 21 weeks of gestation (coded to Exposure during pregnancy).  The subject also experienced anaemia 27 days after vaccination. Considering the implausible temporal relationship between vaccination and reported event, no evidence for a biological mechanism that could cause the event, history of preterm live birth and presence of risk factors (spotting , Rh blood type - treated with Rhogam, candidiasis and was treated with Diflucan and subchorionic haemorrhage), the event of preterm labor was assessed as not related to the study vaccine. The co-administered drugs further confound this case. 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 drug exposure during pregnancy was assessed as not related considering the intended use of the vaccine. The event of anaemia was assessed as not related to study vaccine as the clinical course suggests that the reported conditions (spotting and subchorionic haemorrhage) and hemodynamic changes associated with pregnancy as a more plausible explanation for the event.The company assessed the event preterm labor as serious (medically significant).