Its a metaphor for the sudden deliverance of Israel after the time of Jacobs trouble. The slow long waiting culminating in sudden sharp pains and then deliverance is the metaphor being used.
See:
Isaiah 66:7-9
7 “Before she goes into labor,
she gives birth;
before the pains come upon her,
she delivers a son.
8 Who has ever heard of such things?
Who has ever seen things like this?
Can a country be born in a day
or a nation be brought forth in a moment?
Yet no sooner is Zion in labor
than she gives birth to her children.
9 Do I bring to the moment of birth
and not give delivery?” says the Lord.
“Do I close up the womb
when I bring to delivery?” says your God.
A couple commentaries on this :
Jamieson-Fausset-Brown Bible Commentary
and : Gills exposition of the bible
See:
Isaiah 66:7-9
7 “Before she goes into labor,
she gives birth;
before the pains come upon her,
she delivers a son.
8 Who has ever heard of such things?
Who has ever seen things like this?
Can a country be born in a day
or a nation be brought forth in a moment?
Yet no sooner is Zion in labor
than she gives birth to her children.
9 Do I bring to the moment of birth
and not give delivery?” says the Lord.
“Do I close up the womb
when I bring to delivery?” says your God.
A couple commentaries on this :
Jamieson-Fausset-Brown Bible Commentary
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Jeremiah 30:6
Ask ye now, and see whether a man doth travail with child? wherefore do I see every man with his hands on his loins, as a woman in travail, and all faces are turned into paleness?
6. Ask—Consult all the authorities, men or books, you can, you will not find an instance. Yet in that coming day men will be seen with their hands pressed on their loins, as women do to repress their pangs. God will drive men through pain to gestures more fitting a woman than a man (Jer 4:31; 6:24). The metaphor is often used to express the previous pain followed by the sudden deliverance of Israel, as in the case of a woman in childbirth (Isa 66:7-9).
paleness—properly the color of herbs blasted and fading: the green paleness of one in jaundice: the sickly paleness of terror.
and : Gills exposition of the bible
Jeremiah 30:6 Ask ye now, and see whether a man doth travail with child?
&c.] Look into the histories of former times, inquire of those most versed in them, whether ever there was such a thing in the world as that a man should travail with child; ask one and, another you see in distress, whether that is their case or not, which looks so much like it; and since there never was such an instance, nor is it possible that there should: wherefore do I see every man with his hands his loins, as a woman in
travail;
the usual posture of women in such a condition, trying hereby to abate their pain, and ease themselves. This metaphor is made use of, both to express the sharpness and shortness of this distress; as the pains of a woman in travail are very sharp, yet short, and, when over, quickly forgotten; and so it wilt be at this time; it will be a sharp trial of the church and people of God; but it will last but for a short time; and the joy and happy times that will follow will soon cause it to be forgotten: and all faces are turned into paleness
at the departure of the blood, through fear and trembling. The Septuagint and Vulgate Latin versions render it "the yellow jaundice"; their faces were of the colour of such persons that have that disease upon them; or, as others, the green sickness.