>>1965
As far as I know, the story was first collected in a volume called "胎児異変わたしの赤ちゃん" (Unusual Fetus - My Baby), published by Hibari Shobo in January 1975. It's most likely appeared in several collections since then. I scanned it out of this "Best of" volume that is actually titled after it - the Japanese title of the story is "赤い花", literally "Red Flower(s)". Interestingly, the cover gives its own, alternate English translation.