A beautiful piece. My heart aches for you, and those around you, but most especially for your baby.
Nitpicking, I would either switch the title to "Sadness of a Soul Unborn" or switch the words in the last line of each stanza to match the title now. Personally, I like the latter better, as it has better flow. The third line in the first stanza, 'lul' is spelled 'lull', and in the second line of the fourth stanza, 'trow' should be 'throw'
The last stanza is my favorite, as I have thought this myself, about my past and when others make that choice. You worded this beautifully, and it not only speaks but sings. You have grown as a writer already, I think. This is a wonderful way to remember what almost was, and something that you will never forget.
I hope that whereever your baby is, they have found peace, and will know the love you didn't get to show them.