This is a serious study case initially received on 26-Nov-2018, concerning a 28-year-old adult, female, pregnant subject of body weight 159 lbs, height 62.6 inches and body mass index (BMI) 28.5, a study on pregnancy outcomes in women immunized with seasonal cell culture influenza trivalent (TIVc) or quadrivalent (QIVc) vaccine during pregnancy. The subject did not have any obstetrical history. The subject had no history of offspring with major congenital malformation. Also, the subject had no maternal/paternal history with major congenital malformations. The subject didn't have a prior history of use of tobacco, alcohol or illicit drugs during pregnancy. The subject was allergic to drug (cephalothin). The subject's last menstrual period date was 20-Aug-2018. At the gestational age of 10 weeks the pregnancy subject's pregnancy was collected, and no complications were noted. The type of pregnancy was reported as singleton. On 03-Nov-2018, the subject was administered Flu Vaccine Cell Subunit QIV NVD (batch number: 252232, dose, route of administration, expiry date and anatomical location: not reported) for an unknown indication (explicitly considered as exposure during pregnancy). On an unspecified date, after vaccination, the subject's pregnancy complication was reported as oligohydramnios. On 10-Nov-2018, the subject's cystic fibrosis mutation analysis showed no any congenital malformation. On 14-Nov-2018, the subject's first trimester screening showed no congenital malformation. From 15-Nov-2018, the subject started using OB complete (300mg, orally, qid) for healthy pregnancy and the medication is ongoing. On 08-Dec-2018, the subject's second trimester screening showed no congenital malformation. The subject's estimated date of delivery was reported as 27-Nov-2019. The outcome of the event oligohydramnios was not reported. Follow-up received from other health professional on 13-Dec-2018: The reporter updated the details of OB-complete medication (dose, units, frequency, start date and status). The same was amended in the narrative. Follow-up received from other health professional on 03-Apr-2019: The case was updated from non-serious to serious as a new event Oligohydramnios was added. It was reported that, on 08-Dec-2018, the subject's second trimester screening showed no congenital malformation. The narrative was amended accordingly.; Reporter's Comments: A 28-year-old pregnant subject was administered Flu Vaccine Cell Subunit QIV at 10 weeks of gestational age (explicitly considered as vaccine exposure during pregnancy). The subject experienced oligohydramnios, unspecified period post vaccination. Considering the lack of information important for the causality assessment such as onset latency between the vaccination and reported event, more plausible causes/alternate aetiologies, the company assessed the causality of event oligohydramnios as unassessable. The causality of the event vaccine exposure during pregnancy assessed as not related to study vaccine, considering the intended use of the vaccine. The case will be further assessed upon receipt of follow up information. The company assessed the event oligohydramnios as serious (Medically significant).