You seem to be assuming that a baby was conceived in the same place as it was born. Mary Nolan may have gone away to work, become pregnant and returned (or gone to Portumna) to have her baby. Or she may have met her swain at a fair or on a trip to the seaside or while visiting relatives.
Going away to work and returning pregnant is a strong possibility. The Nolan family is my actual focus. I believe the witness Anne Nolan was my grt grandmother. The father Ned Nolan died in 1878. Mrs Dolphin of London evicted the family in 1879, my Ann then emigrated to the US. Ed (Ned) Jr. died in Portumna 1882, the mother Eliz died in the workhouse in 1894. I am following up on a hunch that the Andrew Nolan living with my grt grandmother in 1895 was the son of Andrew Briggs. I lost track of Mary Nolan and her sister Elizabeth. I was hoping if I could ascertain where Mary connected with Andrew Briggs, I might pick up her trail.