Psalm 127 is a Psalm of gratitude. The Psalmist praises God for the gift of children, who are “vessels” filled with His love (127:3-5).
The Psalmist describes children as “a heritage from the Lord”, because through them God perpetuates the world (127:3). Childbirth is also considered a blessing, because children are “happy”, not only to their parents but also to God (127:4).
Today Psalm 127 is used during childbirth. It has come to represent Psalm 128 in the Latin Rite of the Mass. Psalm 127 is recited or sung after the Liturgy of the Eucharist on Sundays outside Lent, and after Mass on Solemnities, Feasts, and Memorials of the Lord. Psalm 128 is recited or sung instead on weekdays during Lent, as Psalm 126 is used on Sundays outside Lent.
Though Psalm 127 has a place in modern Catholic liturgy as a prayer for children, it was originally a thanksgiving Psalm. In Psalm 128, the Psalmist prays for “sons”.
In Psalm 127, the Psalmist praises God for blessing him with “daughters”, not only sons. He compares his children to productive trees in a vineyard, where both supply food and shelter (127:3-5).