Parashas Eikev · Passuk 7:13
[God] will favor you and bless you and multiply you—blessing your issue from the womb and your produce from the soil, your new grain and wine and oil, the calving of your herd and the lambing of your flock, in the land sworn to your fatherscfathers See note at 1.35. to be assigned to you.
Torah Temimah points to Berachos 51b.
TT lemma: וברך פרי בטנך (unit 1 of 2).
English: R’ Natan says: Whence that a woman’s fruit of the womb is blessed through the man’s fruit of the womb? As it is said, “He will bless the fruit of your womb” — it does not say “her womb” but “your (masc.) womb.”
Custom (linguistic inference on “your womb”)
The blessing of offspring for the wife is included in the blessing given to the husband.