I have actually met two women who didn’t know they were pregnant AND carried to term. It’s not that uncommon. One found out when she started having leg pain and the doppler US confirmed she had a large clot in her leg and - surprise - an 8 month pregnancy. The other one just blussfully didn’t know until she went into labour and delivered a 9lb baby at home by herself, her 2nd child. Both were obese and in denial I think.