Palpitations; Product administration interrupted; Product availability issue; Vaccine exposure during pregnancy; This spontaneous prospective pregnancy case was reported by a consumer and describes the occurrence of PALPITATIONS (Palpitations), PRODUCT ADMINISTRATION INTERRUPTED (Product administration interrupted), INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (Product availability issue) and EXPOSURE DURING PREGNANCY (Vaccine exposure during pregnancy) in a 35-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 040C21A) for COVID-19 vaccination.     No Medical History information was reported.    On 16-Aug-2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. Last menstrual period and estimated date of delivery were not provided. On an unknown date, the patient experienced PALPITATIONS (Palpitations), PRODUCT ADMINISTRATION INTERRUPTED (Product administration interrupted), INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (Product availability issue) and EXPOSURE DURING PREGNANCY (Vaccine exposure during pregnancy). At the time of the report, PALPITATIONS (Palpitations), PRODUCT ADMINISTRATION INTERRUPTED (Product administration interrupted), INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (Product availability issue) and EXPOSURE DURING PREGNANCY (Vaccine exposure during pregnancy) outcome was unknown.            It was reported that Patient started experiencing palpitations on Thursday 29-JUL-2021. She drank some water and went to sleep but the palpitations continued and then she went to the emergency room  where she was diagnosed and was advised not to take the second dose of Moderna until she meet a primary care doctor. She had to return to the emergency room the Saturday because the palpitations continued, they repeated the test, but couldn't find what was cause. patient herself did some research and bought a bottle of 250mg Magnesium and within a fewhours she felt it less. Day and half later iit was gone. After seeing her primary care doctor, she got her second dose the same day. Just a few day ago, she  noticed the palpitations but not that frequent.  This case concerns a 35 year old female who is reportedly pregnant with an unknow gestational age, no relevant history and a history the event of palpitations after the first dose of mRNA-1273 who experienced the non-serious unlisted event of Maternal exposure during pregnancy the day of and the unlisted non-serious event of Palpitations several days after the second dose of mRNA-1273. Re-challenge of the first dose is positive for Palpitations as the event recurred with the second dose and not applicable for the second dose as no further dosing is expected. Benefit-risk relationship of mRNA-1273 is not affected by this report.   This case was linked to MOD-2021-271913 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 01-Oct-2021: Followup received on 04-Oct-2021 which contains no newinformation.; Sender's Comments: This case concerns a 35 year old female who is reportedly pregnant with an unknow gestational age, no relevant history and a history the event of palpitations after the first dose of mRNA-1273 who experienced the non-serious unlisted event of Maternal exposure during pregnancy the day of and the unlisted non-serious event of Palpitations several days after the second dose of mRNA-1273. Re-challenge of the first dose is positive for Palpitations as the event recurred with the second dose and not applicable for the second dose as no further dosing is expected. Benefit-risk relationship of mRNA-1273 is not affected by this report.