Neonatal SVT; Vaccinated twice during pregnancy/third trimester; This is a spontaneous report received from contactable reporter(s) (Consumer or other non HCP). The reporter is the parent.  A fetus male patient was exposed to bnt162b2, bnt162b2 omi ba.4-5 (BNT162B2, BNT162B2 OMI BA.4-5), transplacental, administration details for the mother: on 17Nov2022 at 18:00 as dose 5 (booster), single (Lot number: GJ6739), in left arm for covid-19 immunisation. The mother of the patient was 31 years old at the time of vaccination. The mother's relevant medical history included: "Hashimotos" (unspecified if ongoing). Date of last menstrual period of the mother: 01Apr2022. The mother was 32 weeks pregnant at the time of exposure to bnt162b2, bnt162b2 omi ba.4-5. The mother was 33 weeks pregnant at the event onset. The mother is expected to deliver a baby(s) on 06Jan2023. Concomitant medication(s) included: TDAP taken for immunisation, on 21Oct2022 as dose 1, single; LEVOTHYROXINE; BABY ASPIRIN; PRENATAL VITAMINS [MINERALS NOS;VITAMINS NOS]. The mother's vaccination history included: moderna (Dose 4 (Booster), Single, Prev dose lot number=051B22A, Prev dose vaccine location=Left arm), administration date: 06Aug2022, for COVID-19 immunization; moderna (Dose 3 (Booster), Single, Prev dose lot number=058H21A, Prev dose vaccine location=Left arm), administration date: 22Nov2021, for COVID-19 immunization; bnt162b2 (Dose 2, Single, Prev dose lot number=EW0173, Prev dose vaccine location=Left arm), administration date: 30Apr2021, for COVID-19 immunization; bnt162b2 (Dose 1, Single, Prev dose lot number=EW0158, Prev dose vaccine location=Left arm), administration date: 09Apr2021, for COVID-19 immunization. The following information was reported: MATERNAL EXPOSURE DURING PREGNANCY (hospitalization, congenital anomaly, life threatening) with onset 17Nov2022 at 18:00, outcome "recovering", described as "Vaccinated twice during pregnancy/third trimester"; SUPRAVENTRICULAR TACHYCARDIA (hospitalization, congenital anomaly, life threatening) with onset 14Jan2023 at 13:00, outcome "recovering", described as "Neonatal SVT". The patient was hospitalized for maternal exposure during pregnancy, supraventricular tachycardia (hospitalization duration: 3 day(s)). It was also reported that Event results in Prolongation of existing hospitalization (vaccine received during existing hospitalization, as reported). The events "vaccinated twice during pregnancy/third trimester" and "neonatal svt" required physician office visit and emergency room visit. Therapeutic measures were taken as a result of supraventricular tachycardia, treatment included Adenosine, propranolol.  Clinical courses: Vaccinated twice during pregnancy including: Pfizer bivalent. Son experienced SVT minutesnafter delivery with no past  family  history of arrhythmia and no SVT documents: during pregnancy NSTs. Neonatal SVT occurred with a rate of about 300 bpm, converted with adenosine, immediately after birth on (withheld) and then again a few weeks later at home. Son was placed on propranolol and was well controlled. Medicine was tapered and stopped around 6-7 months of age. Son is 9 months, and his SVT is believed to be in remission at this time. Risk may be vastly: outweighed by benefits. The reporter is not an anti-vaxxer, but does wonder if her vaccination during pregnancy whether based on fact of vaccination or timing of its administration: during third trimester, contributed to neonatal SVT of her son. She hopes this will be looked into given known incidence of cardiac impacts of COVID-19 and known incidence of myocarditis, particularly in males. myocarditis, particularly in males.; Sender's Comments: Linked Report(s) : US-PFIZER INC-202300351826 same reporter, different patient and AE(baby/mother);US-PFIZER INC-202300351759 same reporter, different patient and AE(baby/mother);