But Abram said to Sarai, “Behold, your servant is in your power; do to her as you please.” Then Sarai dealt harshly with her, and she fled from her.
Genesis 16:6
In God's economy, the slave-master relationship takes precedence over wife-husband. (Why? I don't know, exactly, but see Exodus 21:1-6.) This is why a handmaid's children belonged to her mistress as much as they belonged to her, and why Hagar would still be under Sarai's authority despite also being Abram's concubine.
#lekhlekha
In most agrarian cultures, including the ANE, barrenness was considered shameful. People thought it must be the woman's fault. (They weren't always wrong.) When Sarai's handmaid became pregnant, she believed herself to be morally superior and more divinely favored. This was a predictable and expected outcome.
Genesis 16:4
https://vimeo.com/877862826?share=copy
https://vimeo.com/877095670?share=copy