Some Bible translations interpret these verses in such a way as to indicate that pre-destination is being taught here. Others render it instead with the thought that Jehovah has "written down" the pattern (DNA code?) of the developing embryo.

Literal word-for-word renderings from Hebrew interlinears:

  • A: Ps 139:15, 16 - "not he-was-hidden frame-of-me from-you when I-was-made in-the-secret-place I-was-woven-together in-depths-of earth [16] body-of-me they-saw eyes-of-you and-in book-of-you all-of-them they-were-written days they-were-ordained [yatsar] and-not one of-them." - The NIV Interlinear Hebrew-English Old Testament, Zondervan, 1982.
  • B: [15] "Not-was-concealed my-bone from-thee; when I-was-made in-the-hiding-place, I-was-embroidered in-the-lowest-parts-of the-earth. [16] My-unformed-substance saw thy-eyes; and-upon thy-book all-of-them were-written, [as-to]-the-days [when]-they-were-fashioned [yatsar]; and-[there-was]-not one amongst-them." - The Interlineary Hebrew and English Psalter, Zondervan, 1979 printing.
  • C: [15] "Not-were-hidden my-bones from-you when I-was-made in-secret; when-I-was-woven in-the-depths-of the-earth. [16] My-embryo saw your-eyes; and-on Your-book all-of-them were-written; The-days they-were-formed [yatsar] and-(was)-not one among-them." - The Interlinear Bible, Baker Book House, 1982. 


A Concise Hebrew and Aramaic Lexicon of the Old Testament tells us about yatsar, the ancient Hebrew word in question here:
"form, shape (as a potter) - 1. subj. men: form, fashion: .... 2. subj. God: create, form (older, concrete synonym of bara) .... be formed Ps. 139:16." - p. 141, Eerdmans, 1988.
 
Some Bible translations of Ps. 139:15, 16:
 
  • 1. [15] "My frame was not concealed from you when I was shaped in a hidden place, knit together in the recesses of the earth. [16] Your eyes saw my unformed limbs; they were all recorded in your book; in due time they were formed [yatsar], to the very last one of them." - Tanakh, Jewish Publication Society, 1985.
  • 2. [16] "Your eyes saw my embryo; and in Your book all (my members) were written; the days they were formed [yatsar], and none (was) among them." - King James II Version (the accompanying text found in C. above).
  • 3. [15] "my body is no mystery to thee, how I was secretly kneaded into shape and patterned in the depths of the earth. [16] Thou didst see my limbs unformed in the womb, and in thy book they are all recorded; day by day they were fashioned [yatsar], not one of them was late in growing" - New English Bible, Cambridge University Press, 1971.
  • 4. Footnote for Ps. 139:13-16: "God formed him in the womb (poetically called the depths of the earth) and knew his character from his conception." - The New Oxford Annotated Bible, Oxford University Press, 1977.
  • 5. Footnotes: Ps 139:15 - "The depths of the earth: figurative language for 'the womb'; stressing not so much the darkness of the place as the hidden, mysterious nature of the operations which occur there." Ps 139:16ff. - "The text of these three verses is obscure in several places." - The New American Bible, St. Joseph edition, 1970.
Ps. 139:16 - "Mine unformed substance Thine eyes saw, And on Thy book all of them are written, The days they were formed--And not one among them." -Young's
Ps. 139:16 - "Thine eyes did see my unformed substance, and in thy book all my members were written; during many days were they fashioned, when as yet there was none of them." - BBE
Ps. 139:16 "Thy eyes saw my substance, not yet formed; and in thy book all my members were written, which in continuance were fashioned, when as yet there was none of them." - Webster's

The wording of verse 16 is a little obscure. Coupled with that is the possible ambiguity for the Hebrew word yatsar. The New American Exhaustive Concordance of the Bible, Holman Bible Publishers, 1981, tells us yatsar literally means "to form, fashion," but it has been rendered in the New American Standard Bible in the following ways: Creator (1), devises (1), earthenware (1), fashion (1), fashioned (1), fashioning (2), fashions (1), formed (20), forming (2), forms (2), made (1), Maker (4), maker (2), ordained (1), planned (4), potter (9), potter's (7), potters (1).

Obviously, the majority of renderings (56) mean "form or create" (including "potter"), but in 5 instances the NASB translators have rendered it as "planned" or "ordained." It is this possible meaning that probably has allowed some translators to interpret the somewhat obscure Hebrew phrasing as intending "pre-destination" or something similar.
Young's Concordance, however, shows that the KJV translators rendered yatsar only once as "purpose" and all others (60) with the meanings synonymous with "form, fashion, make," etc. That single instance is found at Is. 46:11 -
"I have spoken it, I will bring it to pass;

I have purposed it, I will also do it." - KJV.

Since this is the only time yatsar is interpreted as "purposed" (at least in the KJV), it seems more likely that it also should have been rendered as "formed." This is even more proper when we see that the above-quoted part of Is. 46:11 is a parallelism. That is, the first half is close in meaning to the second half. (Poetic repetition for emphasis and effect.)
Since the second half of the first statement ("I will bring it to pass") is obviously parallel (and equal) to the second half of the second statement ("I will also do it"), we might expect the first half of the first statement ("I have spoken it") to be parallel (and equal) to the first half of the second statement. In that case "I have spoken it" might better be paralleled by "I have formed (yatsar) it [the word or words spoken]."
* This not only fits the parallel better, but makes the translation of yatsar consistent throughout the KJV.
The ancient Greek translation of the Old Testament (which is frequently quoted in the New Testament), the Septuagint, translates yatsar as "created" (ktizo) in the Is. 46:11 passage examined above. More importantly it translates the last part of Ps. 139:16 itself as "of-day they-shall-be-formed [plasthesontai] and nothing among them." The Hebrew word yatsar, then, was translated here by the ancient Greek word plasthesontai which, again, means "formed or molded," not "purposed" or "ordained" (see Thayer, #4111 and Septuagint).
The following translations render yatsar at Ps. 139:16 as "formed," "made," "fashioned," etc. (not "ordained" or "planned"): KJV; NKJV; RSV; NRSV; NEB; REB; AT; BBE; NAB (1991); LITV; MKJV; Tanakh; Young's; JPS 1917; Byington; Rotherham; Darby; and Webster's; etc.
But even if yatsar could be honestly rendered as "purposed" or even "ordained," it is obviously a rare occurrence, and we would be safer in assuming it means "formed," "fashioned," etc. unless context demanded otherwise.
It seems more likely to me that, given the probable meaning of yatsar and the literal wording of the actual Hebrew (and Greek of the Septuagint), pre-destination is not being taught in these verses. ----- See Insight book article on "Foreknowledge, Foreordination".
.................................................................
NOTE
* Young's Literal Translation of the Holy Bible; KJIIV (and MKJV); ETRV ("made"); Septuagint ("created").