Proper structure will give your appreciation letter steady pace and flow. These may not seem like things that matter in an appreciation letter, but they make a difference in terms of readability and the impact your letter has. Just like with letters for after an interview, you need the time to craft this letter carefully.
This includes women who have suffered miscarriages. Losing a child is losing a child, it is no different. And anyone who would judge you or disagree is a soulless individual. If you have never experienced it, there is no room for your opinion.