The Church bears children: Psalm 126 v4

The Body of the Dead Christ in the Tomb Öffentliche Kunstsammlung, Basel

4	V	Cum déderit diléctis suis somnum: * ecce heréditas Dómini fílii : merces, fructus ventris.
	NV	quia dabit dilectis suis somnum.Ecce hereditas Domini filii, merces fructus ventris.
	JH	sic dabit diligentibus se somnum.  Ecce hereditas Domini filii : merces fructus uentris.
		ὅταν δῷ τοῖς ἀγαπητοῖς αὐτοῦ ὕπνον ἰδοὺ ἡ κληρονομία κυρίου υἱοί ὁ μισθὸς τοῦ καρποῦ τῆς γαστρός

Cum (When) déderit (he will give) diléctis (the beloved) suis (his) somnum (sleep): * ecce (behold) heréditas (the inheritance) Dómini (the Lord) fílii (sons): merces (the reward), fructus (fruit) ventris (of the womb)

do, dedi, datum, are, to give,

diligo, lexi, lectum, ere 3  to love; to flatter, make pretence of loving.

somnus, i, m.  during sleep. ecce, adv.  lol see! Behold

hereditas, atis, /. an inheritance, possession; In a fig. sense, the chosen people, the Israelites, the Church,

filius, ii, m. a son.

merces, edis,  a reward

fructus, us, m.  fruit, produce; the fruit of the soil, trees; a reward; the fruit of the womb, children, posterity

venter, tris, m. lit., the belly, the body, the bowels, the breast, heart. womb

DR	When he shall give sleep to his beloved, behold the inheritance of the Lord are children: the reward, the fruit of the womb.
Brenton	While he gives sleep to his beloved.  Behold, the inheritance of the Lord, children, the reward of the fruit of the womb.
MD	For to His loved ones He giveth it in sleep.  Behold children are a gift from the Lord, the fruit of the womb a reward.
RSV	For he gives to his beloved sleep. Lo, sons are a heritage from the LORD, the fruit of the womb a reward.
Cover	For so he giveth his beloved sleep. Lo, children, and the fruit of the womb, are an heritage and gift that cometh of the Lord.
Knox	Is it not in the hours of sleep that he blesses the men he loves? Fatherhood itself is the Lord’s gift, the fruitful womb is a reward that comes from him.
Grail	When he pours gifts on his beloved while they slumber. Truly sons are a gift from the Lord, a blessing, the fruit of the womb.

St Augustine interprets this verse as a reference to Christ on the cross, a sense that fits well with the placement of the psalm at None:

But where did He sleep? On the Cross.

And the children referred to are therefore the sons and daughters of Christ made possible by the creation of the Church:

When He slept on the Cross, He bore a sign, yea, He fulfilled what had been signified in Adam: for when Adam was asleep, a rib was drawn from him and Eve was created; so also while the Lord slept on the Cross, His side was transfixed with a spear, and the Sacraments flowed forth, whence the Church was born. For the Church the Lord's Bride was created from His side, as Eve was created from the side of Adam. But as she was made from his side no otherwise than while sleeping, so the Church was created from His side no otherwise than while dying...

The Church bears children, the Bride of Christ; and if she bears them, she travails of them. In figure of her, Eve was called also the Mother of all living. He who said, My little children, of whom I travail in birth again, until Christ be formed in you, was among the members of her who travails. But she travailed not in vain, nor brought forth in vain: there will be a holy seed at the resurrection of the dead: the righteous who are at present scattered over the whole world shall abound. The Church groans for them, the Church travails of them; but in that resurrection of the dead, the offspring of the Church shall appear, pain and groaning shall pass away....

For each of us individually, the message is that death is not something to be feared, as Cassiodorus explains:

The next words explain when those people earlier ordered to sit are to rise, namely at the time when the faithful are welcomed into rest; for them death is sleep and untroubled intermission. God's beloved are those who seek Him with zealous love. One can infer from this passage the great gifts bestowed on them, since they have received such a title, for one addressed as God's beloved is undoubtedly adorned with eternal blessedness....

The reward though, are the sons and daughters born through baptism, according to Cassiodorus:

The fruit of this womb, the offspring born of the Virgin, the reward is the Lord's entire inheritance, which on rising again is sent to possess heaven, and will rejoice with the Lord in eternal blessedness. The reward is said to have been rendered to humankind; of it Psalm 2 says: Ask of me, and I will give thee Gentiles for thy inheritance." 

Psalm 126: Nisi Dominus 

Vulgate	Douay-Rheims
Canticum graduum Salomonis.	A gradual canticle of Solomon.
1.  Nisi Dominus aedificaverit domum:*  in vanum laboraverunt qui aedificant eam.	Unless the Lord build the house, they labour in vain that build it.
2.  Nisi Dominus custodierit civitatem:* frustra vigilat qui custodit eam.	Unless the Lord keep the city, he watches in vain that keeps it.
3.  Vanum est vobis ante lucem surgere:* surgite, postquam sederitis, qui manducatis panem doloris.	2 It is vain for you to rise before light, rise after you have sitten, you that eat the bread of sorrow.
4.  Cum dederit dilectis suis somnum:* ecce hereditas Domini, filii merces, fructus ventris.	When he shall give sleep to his beloved, 3 behold the inheritance of the Lord are children: the reward, the fruit of the womb.
5.  Sicut sagittae in manu potentis:* ita filii excussorum.	4 As arrows in the hand of the mighty, so the children of them that have been shaken.
6.  Beatus vir, qui implevit desiderium suum ex ipsis:* non confundetur cum loquetur inimicis suis in porta.	5 Blessed is the man that has filled the desire with them; he shall not be confounded when he shall speak to his enemies in the gate

And continue on to the next part in this series, notes on verse 5 of Psalm 126.