Focus on what's happening to the person giving birth. What are they feeling as giving birth is the ultimate strain emotionally and physically. It can be orgasmic depending on the story but is often painful and fully drains a character of their energy and typically makes it where they can't move freely anymore. Focus what's happening on their body while in labor. The belly contracting and squeezing against their will. If they have a vagina, how their cervix opens up during labor and how their vagina slightly spreads open as they get closer to birth. If the character has a penis, depending if it's penial or anal birth describe that. If it's a penis birth how the tip of their dick opens and expands and how their shaft bulges as the life travels down their shaft before giving birth. And how the character can feel every bit of it.