New International Version
Adam made love to his wife Eve, and she became pregnant and gave birth to Cain. She said, "With the help of the LORD I have brought forth a man."
New Living Translation
Now Adam had sexual relations with his wife, Eve, and she became pregnant. When she gave birth to Cain, she said, "With the LORD's help, I have produced a man!"
English Standard Version
Now Adam knew Eve his wife, and she conceived and bore Cain, saying, “I have gotten a man with the help of the LORD.”
New American Standard Bible
Now the man had relations with his wife Eve, and she conceived and gave birth to Cain, and she said, "I have gotten a manchild with the help of the LORD."
King James Bible
And Adam knew Eve his wife; and she conceived, and bare Cain, and said, I have gotten a man from the LORD.
Holman Christian Standard Bible
Adam was intimate with his wife Eve, and she conceived and gave birth to Cain. She said, "I have had a male child with the LORD's help."
New World Translation 2013
Now Adam had sexual relations with his wife Eve, and she became pregnant.a When she gave birth to Cain,b she said: “I have produced* a male child with the help of Jehovah.”
It has been contended that adding "help" as NIV does is unwarranted because that adds to what the Hebrew text actually states. Compare YLT for example. However, is the addition of this word a deliberate mistranslation? Not in my estimation because part of translation involves making things clear for one's receptor audience: translating is going from the source language to the receptor language. Producing a stilted "literal" translation may actually be misleading. Note how many translations above use the word "help." The fact is that "help" is an understood/implicit element of the utterance.
Cambridge Bible offers this explanation for why "help" might be used:
I have gotten a man with the help of the Lord] Literally, “I acquired (or, have acquired) man, even Jahveh.” Eve’s four words in the Hebrew (ḳânîthi îsh eth-Yahveh) are as obscure as any oracle.
(i) The difficulty was felt at a very early time, and is reflected in the versions LXX διὰ τοῦ θεοῦ, Lat. per Deum, in which, as R.V., the particle êth is rendered as a preposition in the sense of “in conjunction with,” and so “with the help of,” “by the means of.”
König, who holds an eminent position both as a commentator and as a Hebrew grammarian and lexicographer, has recently strongly defended the rendering of êth as a preposition meaning “with,” in the sense here given by the English version “with the help of” (see Z.A.T.W. 1912, Pt i, pp. 22 ff.). The words will then express the thanksgiving of Eve on her safe deliverance of a child. It is a pledge of Divine favour. Child-birth has been “with the help of the Lord.”
(ii) The Targum of Onkelos reads mê-êth = “from” (instead of êth = “with”), and so gets rid of the difficulty: “I have gotten a man from Jehovah,” i.e. as a gift from the Lord. But this is so easy an alteration that it looks like a correction, and can scarcely be regarded as the original text. Praestat lectio difficilior.
From NET Bible:
tn Heb “with the Lord.” The particle אֶת־ (’et) is not the accusative/object sign, but the preposition “with” as the ancient versions attest. Some take the preposition in the sense of “with the help of” (see BDB 85 s.v. אֵת; cf. NEB, NIV, NRSV), while others prefer “along with” in the sense of “like, equally with, in common with” (see Lev 26:39; Isa 45:9; Jer 23:28). Either works well in this context; the latter is reflected in the present translation. Some understand אֶת־ as the accusative/object sign and translate, “I have acquired a man – the Lord.” They suggest that the woman thought (mistakenly) that she had given birth to the incarnate Lord, the Messiah who would bruise the Serpent’s head. This fanciful suggestion is based on a questionable allegorical interpretation of Gen 3:15 (see the note there on the word “heel”).