The context is rather clear to me, but let's clear up a couple of points. The word "beten" is translated as abdomen sometimes but in every other ten appearances that it makes in the Torah it means "womb". That is why "thought for thought" translations prefer "womb" to abdomen. And in the same way "thigh" is usually an euphemism for sexual organs, whether male or female.
Commentary on Numbers 5:11-31
By the way you should be following along. One of the sources that I provided earlier shows that the abortion interpretation goes back to at least 1913. It is not a new interpretation.