Subserous leiomyoma of uterus; Anxiety; Vaccine exposure during pregnancy; This is a serious observational study case initially received on 12-Jun-2019, concerning a 34-year-old adult female, pregnant subject  of body weight 154.5 lbs, height 63 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 obstetrical history noted that the subject had one previous pregnancy that included spontaneous abortion with no birth defects noted. The subject had no history of offspring with major congenital malformation. Also, the subject had no maternal or paternal history with major congenital malformations. The subject's historical condition included malignant tumor of thyroid which stopped on 01-Mar-2018. The subject's current conditions included migraine, Hashimoto's thyroiditis, hypertension and allergies. The subject's concomitant medications included Zyrtec (cetirizine hydrochloride) and Flonase (fluticasone propionate) for allergies, labetalol for hypertension, calcium plus vitamin D3 (calcium, colecalciferol) as supplement, Synthroid (levothyroxine sodium) for Hashimoto's thyroiditis, progesterone for hormonal treatment and prenatal vitamins (minerals nos, vitamins nos) as a vitamin.  The subject's last menstrual period (LMP) date was 04-Feb-2019. The subject did not have a prior history of use of tobacco, alcohol or illicit drugs during pregnancy. The type of pregnancy was singleton.     On 21-Mar-2019, the subject underwent ultrasound screening and no major congenital malformations were noted.  On 05-Apr-2019, at approximately 08 weeks of gestation, the subject was administered Flu Vaccine Egg Split QIV CSL (influenza vaccine, batch number: YF41608, 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, the subject experienced anxiety and was treated with clonazepam 0.5 mg tablet [frequency: daily (qd) as needed (prn), route of administration: oral and was ongoing]. On the same day, the subject underwent ultrasound screening and no major congenital malformations were noted. On an unspecified date after vaccination, the pregnancy status was collected and subserous leiomyoma of uterus was noted.  On 12-Apr-2019, the subject underwent non-invasive prenatal screening and no major congenital malformations were noted. On 30-May-2019, the subject underwent maternal serum alpha-fetoprotein (MSAFP) test/ serum markers and no major congenital malformations were noted. On 10-Jun-2019, the subject underwent ultrasound screening and no major congenital malformations were noted.  The outcome of the events subserous leiomyoma of uterus and anxiety were not reported.   The subject's corrected estimated date of delivery (CEDD) was 07-Nov-2019 and the estimated date of delivery (EDD) was reported as 11-Nov-2019.; Reporter's Comments: A 34-year-old female pregnant subject experienced anxiety, on the same day after receipt of Flu Vaccine Egg Split QIV at approximately 8 weeks of gestation (considered as vaccine exposure during pregnancy). The subject was also diagnosed with uterine leiomyoma (reported as pregnancy complication), unspecified period post vaccine. Considering the plausible temporal relationship, the event anxiety assessed as related to study vaccine. The concomitant medication levothyroxine considered as confounding factor. The event uterine leiomyoma assessed as not related considering lack of biological mechanism associated with study vaccine. However, the case will be further assessed upon receipt of follow-up information. The event vaccine exposure during pregnancy assessed as not related considering the intended use of study vaccine. The company assessed the event 'subserous leiomyoma of uterus' as serious (medically significant).