I'd say it was incredibly incredibly unlikely, though not impossible. Some years ago I did some researchj looking at the influence of maternal and paternal age in England and Wales on the occurrence of a particular disease. In 1961 (the earliest year I looked at) there were 811281 live births in England and Wales in total. Of these 21 had a maternal age >50, so even for any age over 50 it would be less than one in 40,000 births. Since the decrease is exponential, age 52 would be as rare as hen's teeth, though remotely possible (maybe one case every decade or so in a small country like, for example, Lithuania). Misattributed mothers (due to underage pregnancies where an adult takes the role) would outnumber these cases hundreds of fold. The table for 1961 for England is below.
I had a second cousin, the fifth child in his family, who was born when his mother was 52. His siblings were 24-, 23-, 19- and 13-years older than him.
