Oligohydramnios; Premature delivery; Vaccine exposure during pregnancy; This is an observational study case, initially received from other health professional on 06-Aug-2019, concerning a 24-year-old, female, pregnant subject of body weight: 221 lbs, height: 60 inches and body mass index (BMI): 43.2, enrolled in a prospective observational safety study.  The subject had 3 previous pregnancies which included 2 live birth, and one spontaneous abortion. 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 medical history included nausea. The subject's concomitant medications included Prenatal vitamins (minerals NOS, vitamins NOS) as supplement and promethazine for nausea.   The subject's last menstrual period (LMP) was 15-Jun-2018. The type of pregnancy was singleton. The estimated delivery date (EDD) was 22-Mar-2019 and corrected estimated date of delivery (CEDD) was 05-Mar-2019. The subject did not have a prior history of use of tobacco, alcohol or illicit drugs during pregnancy. The pregnancy status of the subject was collected and there were no complications noted.  On 01-Nov-2018, at gestation age of 19 weeks, the subject was administered Flu Vaccine Cell Subunit QIV NVD [influenza vaccine, subunit influenza virus vaccine polyvalent, batch number: 252664, expiration date, route of administration and anatomical location: not reported] for immunization to influenza virus.  On an unspecified date, unknown amount of time after vaccination, the subject experienced oligohydramnios.  At gestational age of 36.4 weeks, the subject delivered live birth, female neonate by caesarean delivery. The neonate's birth weight was 1928 g, head circumference and body length were not reported. The appearance, pulse, grimace, activity and respiration (APGAR) scores were 8 (one minute) and 8 (five minutes). It was reported that there were no major congenital malformations (MCM) identified at birth.  At the time of initial reporting, the outcome of the event oligohydramnios was not reported.  This case is linked to 201904356, the corresponding child report.  Company comment: The patient was administered Flu Vaccine Cell Subunit QIV NVD at gestation age of 19 weeks (coded as vaccine exposure during pregnancy). On an unknown date after vaccination, the subject experienced oligohydramnios. Chronology needs more clarification. The event of premature delivery was also reported (at gestational age of 36.4 weeks). The patient's medical history of previous spontaneous abortion confounds causality. However, causal role of the suspect vaccine can not be totally excluded and is assessed as related. The event of exposure during pregnancy was assessed as not related considering the intended use of the vaccine.; Reporter's Comments: The patient was administered Flu Vaccine Cell Subunit QIV NVD at gestation age of 19 weeks (coded as vaccine exposure during pregnancy). On an unknown date after vaccination, the subject experienced oligohydramnios. Chronology needs more clarification. The event of premature delivery was also reported (at gestational age of 36.4 weeks). The patient's medical history of previous spontaneous abortion confounds causality. However, causal role of the suspect vaccine can not be totally excluded and is assessed as related. The event of exposure during pregnancy was assessed as not related considering the intended use of the vaccine.