When his mother bore him, his father was already having an affair. By then, his love had already fizzled out, so even if she finally 'laid eggs', it was already too late for them to recover feelings.
When she gave birth to Rigam, due to using a lot of fertility pills, her body had grown weak and sickly. She wasn't physically strong in the first place, so adding this debilitated her.
Jania, his father's mistress, was actually a healer. Healers and water users were famously healthier than others and were likelier to conceive, which was another reason the Lord loved her so much.
She was taken in to supposedly heal Rigam's mother, when in reality she was poisoning her, causing her illness and weak body to act up every so often. She just didn't dare do it so blatantly lest it put the Lord in a difficult position.
