Passage 2.22.6
πλησίον δὲ τῶν Ἀνάκτων Εἰληθυίας ἐστὶν ἱερὸν ἀνάθημα Ἑλένης, ὅτε σὺν Πειρίθῳ Θησέως ἀπελθόντος ἐς Θεσπρωτοὺς Ἄφιδνά τε ὑπὸ Διοσκούρων ἑάλω καὶ ἤγετο ἐς Λακεδαίμονα Ἑλένη. ἔχειν μὲν γὰρ αὐτὴν λέγουσιν ἐν γαστρί, τεκοῦσαν δὲ ἐν Ἄργει καὶ τῆς Εἰληθυίας ἱδρυσαμένην τὸ ἱερὸν τὴν μὲν παῖδα ἣν ἔτεκε Κλυταιμνήστρᾳ δοῦναι---συνοικεῖν γὰρ ἤδη Κλυταιμνήστραν Ἀγαμέμνονι---, αὐτὴν δὲ ὕστερον τούτων Μενελάῳ γήμασθαι.
Near the shrine of the Anakes is a sanctuary of Eileithyia, dedicated by Helen. This occurred when Theseus had departed with Peirithous for the Thesprotians, and Aphidna was captured by the Dioskouroi, and Helen was taken back to Lacedaemon. For they say she was pregnant at the time, and that when she gave birth in Argos, she erected a sanctuary for Eileithyia. The child whom she bore she gave to Clytemnestra—since Clytemnestra was already married to Agamemnon—while Helen herself afterward married Menelaus.