What is the secret behind choosing the word "wahn" (weakness) in Surah Luqman, verse 14, and the word "kurhan" (aversion/dislike) in Surah Al-Ahqaf, verse 15, to describe pregnancy?

The two verses illustrate two different states of the mother during pregnancy. The Almighty's saying, "His mother carried him, in weakness upon weakness," refers to the mother's increasing weakness due to pregnancy. And the Almighty's saying, "His mother carried him with hardship and gave birth to him with hardship," refers to the difficulty of pregnancy and childbirth and the pains accompanying them.