I have been looking for the source of this information but I will have to keep looking. After looking on the National Institute Of Health web site I could not find your statement. I did find it all over the web of those who promote abortion. I wonder why they like this since it really has nothing to do with when life starts. I have wondered about how they came up with the percentage which seem ridiculous to me. How in the world would they come up with this? How would they know? But it besides the point. The indication of your question is because there is spontaneous abortions then it follows they couldn’t have souls.
However:
Conception = life
Life=soul
I can’t tell you why God created people He knew would go to hell. I can’t tell you why anyone dies including those who die shortly after birth.

It is makes more sense to me that He would create souls that would spend eternity with Him who never sinned against Him. Although it is not known what happens to these souls, I believe that they are enjoying perfect bliss./QUOT
My apology for using the

logo. Would have preferred to use an irritation logo, but couldn’t find one. The info below might help. but if you would prefer to read the entire article, please Google: IMPLICATIONS OF DEFINING WHEN A WOMAN IS PREGNANT.
When Is a Woman Pregnant?
To be sure, not every act of intercourse results in a pregnancy. First, ovulation (i.e., the monthly release of a woman’s egg) must occur. Then, the egg must be fertilized. Fertilization describes the process by which a single sperm gradually penetrates the layers of an egg to form a new cell (“zygote”). This usually occurs in the fallopian tubes and can take up to 24 hours. There is only a short window during which an egg can be fertilized. If fertilization does not occur during that time, the egg dissolves and then hormonal changes trigger menstruation; however, if fertilization does occur, the zygote divides and differentiates into a “preembryo” while being carried down the fallopian tube toward the uterus. Implantation of the preembryo in the uterine lining begins about five days after fertilization. Implantation can be completed as early as eight days or as late as 18 days after fertilization, but usually takes about 14 days. Between one-third and one-half of all fertilized eggs never fully implant. A pregnancy is considered to be established only after implantation is complete.
Source: American College of Obstetricans and Gynecologists.