This question has been raised by Pastors and other theologians through comments I heard via radio and video broadcasts. I too shared the interest in learning where this might be in the scriptures of truth, concerning the (Origin) of God setting this standard for a male child and a female child.
40 days for a male child after his birth,
80 days for a female child after her birth.
Ecclesiastes 12 KJV
There are no verses in the scripture where it speaks directly of (why) God set this standard.
 There are however verses where we can "read here a little, and there a little, and piece it together.
Back in 2009 God gave me these verses whereby I have used as my standard for ALL my studies, when I seek God's word in ALL things.
Isaiah 46:8-10 KJV
Remember THIS, and shew yourselves men (:) bring it AGAIN to mind, O ye transgressors. ( are we not all transgressors?) Yep.
9) REMEMBER THE FORMER THINGS OF OLD(:) for I am God, and there is none else(;) I am God, and there is none LIKE me(,)
10) Declaring the End from the Beginning, and from [ANCIENT TIMES] the THINGS THAT ARE NOT YET DONE, saying, My counsel shall STAND, and I will do ALL My Pleasure(:)
It has been my practice to go back to the beginning, even to the days of old and ancient times in order to (try) and learn what it is that God has declared from the beginning through to the end.
This is where I believe I have found the answer to this question.
I begin in Genesis:
Genesis 1:26 KJV
And God said, Let (us) make man in our image, after our likeness(:) and let (THEM) have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over EVERY creeping thing that creepeth upon the earth. 27) And God created man in his own image, in the image of God created he him; (Male and Female) created he (them.)

I believe that God created (them) on the same day, the Sixth day.

Genesis 2:1 KJV
Thus the Heavens and the earth were (finished,) and all the (hosts) of them.
THIS VERSE CONTRADICTS any teachings in a (gap) theory; just thought I might mention it.

IT IS THE (THREE) PERSONS OF GOD WHO ARE DOING ALL THESE THINGS. ( Father, Son/the Word, and the Holy Ghost/Spirit.)
The heavenly Angels were (hosts) of the HEAVENS and Man and woman, the (hosts) of earth.

The SIXTH day God Finished his work Verse 2) And on the SEVENTH day God ended his work which he (had) made; and he rested on the SEVENTH day from ALL his work which he had made.

So we can see clearly here by the Seventh day God rested, Adam and The Rib were made on the Sixth day.
Both male and female. OK, with this understanding we read on in the next passages.
Genesis 2:4 KJV
These are "The Generations" of "The Heavens" and of "The Earth" when THEY were created, IN (THE) DAY that the Lord God made "Earth" and  "The Heavens,"
NOW in verse 7) And the Lord God formed man of the dust of the ground, and breathed into his nostrils the breath of life(;) and man became a living soul.

We know that EVERY BIT of Gods work was Finished on the Sixth day. ( literal day) Therefore we must also know that the FEMALE was also created on the Sixth day.
Many of us are of the mind that The Female was an after thought of God once Adam saw after naming all the fish, beasts of the field, and fowls of the air, and creeping things in Genesis 2:19,20 that there was not a help meet found there for him.
BUT REMEMBER these are the "generations of the Heavens and the Earth.
Therefore God is breaking it down for us; All here, in the SECOND chapter of Genesis.
Understanding again that (the woman) had already been created on the Sixth day.
NOW in verses 8,15) of Genesis 2 we read:.....
And the Lord God planted A garden Eastward IN Eden(;) and there he PUT the man whom he had formed.
And God TOOK the man and PUT him in the Garden which God had planted in verse 8) which was EASTWARD in Eden. We can see CLEARLY that the man, and also the woman must have been created WESTWARD of Eden.
And God commanded HIM Adam the Man, to not eat of the tree of the knowledge of Good and Evil, ONLY to The Man, Adam, after God PUT him in the Garden of Eden.

Where was EVE the Woman?
What is the Time frame that God set for "The man" to PUT him into the Garden ?
I believe it was the same as in Leviticus 12: 2-5
  Male child =the Sabbath day +6 days after the Sabbath =7 days = 1 week
+ another 33 days = 40 days.

The time frame when God BROUGHT her to him in the garden.
Female child = the Sabbath + 13 days= 14 days= 2 weeks
 + three score and six days=20+20+20 + 6= 66 day
14 days + 66 days= 80 days.
 Leviticus 12:2-5

Adam and the Rib began their lives with the Sabbath Rest first.
The same is the case with the 1 year is as 1000 years for all, in the 7 thousandth year of man.
We are nearing the end of the Sixth thousandth year from mans creation.
The 7 thousandth year will begin after the time of Jacob's trouble in finished.


How do we know for sure that Eve the woman, was also created from the RIB of Adam on the Sixth day. And that she was also formed from the dust of the ground WESTWARD of Eden?
Let us read on in Chapter 5) of Genesis where God is telling us of " The BOOK of the generations of Adam."
Genesis 5:1 KJV
THIS is The Book of the generations of Adam(.) IN "THE DAY" THAT GOD CREATED MAN, in the likeness of God made he HIM(;) 2) Male and Female created he THEM(;) and blessed THEM, and called THEIR name Adam, IN (THE) DAY WHEN (THEY) WERE CREATED.
God is specifying THE DAY that (they) were created, therefore we can know for sure that it was the Sixth day, because we read in verse 1 of chapter 2, that the Heavens and the Earth were finished.

God is good, and everything we might have question about in his word, he gives us the answer; " here a little and there a little." IF we take him at his word, and call upon him, he WILL show us ( In HIS word) great and mighty things which we know not.

I believe that Adam and The Rib were created Westward of Eden on the Sixth day, and 40 days after Adam's creation, God PUT him in the Garden, which God had planted that he, Adam, would dress and keep it.
I believe it was another 40 days after God PUT Adam in the Garden of Eden, that the woman was (Brought) to him in the Garden.
Genesis 2:18 and in (19) God formed the animals and fish and fowls and creeping things.
40 days for a Male child.
80 days for a Female child.

Ecclesiastes 3:15 KJV
That which hath been is now(;) AND THAT WHICH IS TO BE HATH ALREADY BEEN(;) and God requireth that which is past.
God requires man to keep (his standard) for the male child born, and also for the Maid/female child born, to be brought before the Lord, in their atonement for sin.
We know that God knew that the woman would be the transgressor of what God actually said concerning the tree of the knowledge of good and evil, and that she would convince Adam to do the same.

We know that God requires the past which he has already told us in Isaiah 46:8-10 KJV that his counsel shall stand. He set the REQUIREMENTS for the male and the female, IN THE BEGINNING, and asked the children of Israel to do the same.
And I believe him.

God Bless You
KML