This is a serious observational study case, initially received on 07-Nov-2018, concerning a 33-year-old, pregnant female, subject of body weight: 115 lbs and height: 62 inches and Body mass index (BMI): 21, enrolled in a prospective observational safety study on pregnancy outcomes in women immunized with AFLURIA QIV, a seasonal quadrivalent vaccine, during pregnancy. The subject had 4 previous pregnancies out of which 2 were of full-term live births, 1 elective abortion and one spontaneous abortion. There were no birth defects reported. This was the subject's fifth pregnancy. The subject did not have any paternal or maternal history with major congenital malformation. The subject didn't have a prior history of use of tobacco, alcohol or illicit drugs during pregnancy. The subject's last menstrual period (LMP) date was 10-Apr-2018. The type of pregnancy was singleton. The gestational age of the subject was 29 weeks (third trimester). The subject's concurrent conditions included Hashimoto's disease, migraine and nausea. The subject's concomitant medication included Prenatal vitamins [minerals nos, vitamins nos, dose: 1 tablet, frequency: once daily (qd), route: oral, started prior to conception] for pregnancy, Levothyroxine [dose: 75 mcg, frequency: once daily (qd), route: oral, started prior to conception] for Hashimoto's disease. On 20-Jul-2018, the subject underwent preterm normal birth weight (PNBW) test and no major congenital malformation was noted. On 27-Jul-2018, the patient started treatment of Zofran [ondansetron, dose: 4 mg, frequency: as needed (prn), route: oral, gestational age: 15.4 weeks] for nausea. On 22-Aug-2018, the subject underwent cystic fibrosis mutation analysis and no major congenital malformation was noted. On 25-Aug-2018, the subject underwent anatomic scan and no major congenital malformation was noted. On 30-Oct-2018, the subject underwent 1 hr glucose tolerance test (1 HR GTT)/haemoglobin electrophoresis test and no major congenital malformation was noted. On 31-Oct-2018, the pregnant subject was administered Flu Vaccine Egg Split QIV CSL (batch number: YF44009, dose, route of administration, anatomical location and expiry date: not reported) (explicitly considered as exposure during pregnancy) for an unknown indication. On 18-Nov-2018, the subject started Cyclobenzaprine HCL (10 mg, prn, oral) for an unknown indication.  On an unknown date, after administration of suspect vaccine, the subject's pregnancy status was collected, and nausea was noted. On 19-Dec-2018, the subject underwent group B streptococcus (GBS) culture test, and the result was positive, but no major congenital malformation was noted. On 03-Jan-2019, the subject's ultrasound showed oligohydramnios, foetal weight: 13 percent and no major congenital malformation was noted. On 07-Jan-2019, the subject's ultrasound showed severe oligohydramnios (plan induction) and no major congenital malformation was noted. On 08-Jan-2019, the subject (gestation age: 39 weeks) gave a live birth to a male infant, vaginally. It was an oligohydramnios induced labour. No major congenital malformation was noted in the infant. The weight of the infant was 3229 grams and the APGAR score were 8 in minute one and 9 in minute five. The subject's estimated delivery date (EDD) was reported as 15-Jan-2019. The outcome of the events was not reported. Follow-up received from the pregnancy registry on 30-Jan-2019: Details about the pregnancy outcome were added in the patient tab under pregnancy information. Historical condition, multigravida, elective abortion and spontaneous abortion were added under other relevant history in the patient tab. Lab tests and relevant tests were added in the patient tab. Concomitant medication: Cyclobenzaprine HCL was added in the product tab. Event: Oligohydramnios, streptococcus test positive and ultrasound scan abnormal were added in the event tab. The narrative was amended accordingly.; Reporter's Comments: A 33-year-old multigravida pregnant subject at the gestational age of 29 weeks, was administered Flu Vaccine Egg Split QIV CSL (coded as vaccine exposure during pregnancy). On an unspecified date after vaccination, the patient experienced nausea. The patient was diagnosed with streptococcal test positive, 1 month 19 days post vaccination and ultrasound abdomen detected oligohydramnios, more than 2 months post vaccination which progressed over a week to severe oligohydramnios requiring induction of labor. The company assessed the causality of the event nausea with the study vaccine as unassessable due to the lack of information regarding the onset latency of the event. The event streptococcal test positive causality assessed as not related considering the bacterial aetiology. The event oligohydramnios lacks known biological evidence associated with the vaccine. Hence, assessed as not related to study vaccine. Advanced maternal age and multigravida are considered as known risk factors for oligohydramnios. Concomitant medications represent a confounding factor. The company assessed the case as serious (medically significant).