This shouldn't come as a big surprise, but losing your wife in childbirth can have a big impact on a person. Like Sadima and Micah's dad.
Before his wife dies, we see a man who is happy and playful. While telling Micah that he heard the baby's first cry: "His father lifted him and swung him in a circle, then embraced him" (3.34). He expresses love for his son, too, by saying: "You're a good boy, Micah. No father ever had a better son" (3.46). See? Warm and fuzzies all around.
But after the horrifying death of his wife in childbirth, he falls apart. He "dropped on his knees beside the bed, mouth open as he patted his wife's face, gripped her hands. Micah heard him whispering, pleading with her to waken" (3.55). He doesn't even notice Micah taking his baby sister away to keep her warm and safe. We can't really blame the dude for getting wrapped up in his own grief, but still.
According to Micah, he's a completely different person after his wife's death. He doesn't talk much, and he's sometimes abusive: "Papa rarely strung that many words together, and grim as they were, it was better than silence—or the flares of anger he had so often now" (5.6). Sadima suffers under his hand, and she has an outburst after he dies: "Our father hated himself and everything in this world" (13.15), she cries out. He is another example of a person broken by cruel events in the world.