Historical Accuracy of Beloved

Beloved by Toni Morrison discusses the history and experiences of slaves in America, and how these experiences haunt those who have escaped from or been freed from slavery. Morrison mentions specific years and ages of her characters in the novel and alludes to connections between the events in the book and historical events in the American South. However, when matching up these dates to the history of slavery in America, they don't fit together quite right.

The book is set in 1873, 8 years after the Civil War. In 1855, Sethe gives birth to Denver. According to Denver's telling of the story, Sethe is 19 when she gives birth to Denver, meaning she would have been born in 1836.

Stick with me, this is where it gets tricky. According to Nan, both she and Sethe's mother were "taken up by" crewmen on the boat they took to an unspecified island. Sethe's mother gets pregnant by someone on the boat's crew and gets rid of the child on the island. This means that at least a year was spent traveling to and staying on the island. If we set the minimum age for surviving a pregnancy at 13, this means that Sethe's mother was at least 14 by the time she reached the states, if not older.

International slave trade was outlawed in America (though people could still trade slaves within America) in 1808, and a very small number of slaves were illegally smuggled into the country after 1808 due to high penalties for not only smuggling but buying smuggled slaves. Assuming Sethe's mother entered the country right at the end of America's international slave trade, she would have been 14 in 1808 making her born in 1797. And if Sethe's mother was born in 1794, that would make her at least 42 if not older at the time of Sethe's birth.

While having a baby at 42 might not seem unreasonable by today's standards, it would have been pretty much impossible for an enslaved woman. For starters, nowadays it is difficult for women at that age to conceive children and deliver them healthily through a traditional birth. On top of that, enslaved women were often forced to work through their pregnancies at the same rate as healthy men, were not provided with extra food, and had no access to prenatal care. Finally, slaves had an average life expectancy of 21-22 in the antebellum South, nowhere near the minimum age of 42 that Sethe's mother would be at the time of Sethe's birth.

In order for the story to match the timeline of American history, Sethe's mother would have to be 42 years old if not older at the time of her daughter's birth, and getting up and continuing to work on the plantation 2-3 weeks later. So what explanantion is there for this impossible feat? Am I missing another piece of evidence in the story that explains this timeline error? And if it truly is an oversight on behalf of the author, why did she include specific ages and years in the story if they don't work? What purpose does that serve? And am I digging too deep into this plot hole?

(Sidenote: I understand that the historical accuracy of the timeline does not have an impact on the message and information conveyed in the book, it just bothers me.)