To make a short story long, Vina was probably incapable of bearing children by the time Pike was returned to Talos IV in "Menagerie".
In "Menagerie" Spock says:
Since precise Spock says thirteen years ago, it must have been between 13.0 and 14.0 years before Spock takes Pike back to Talos IV in "Menagerie".
If precise Spock said eighteen years it would have been between 18.0 and 19.0. But since Spock said approximately eighteen years it may have been between 17.0 and 20.0 years.
Thus Spock took Pike back to Talos IV about 30 to 34.0 years after the
Columbia crashed on Talos IV.
In "The Cage" and "Menagerie", Vina may look about the same age as her actor Susan Oliver, who was born February 13, 1932 and thus was almost 33 when her scenes were filmed on 27 November to 18 December 1934. But she may look much younger:
This implies that Vina looked only about 18.
Number one's attitude certainly indicates that Vina was recorded to be much older at the time of the crash than Yeoman Tina "Lizard girl" Lawton or Yeoman Colt (played by 22-year-old Laurel Goodwin).
In medieval times Princess Agnes (1072/73-1143) of the Holy Roman Empire had at least 22 children born between 1088 and about 1118, about a 30 year period up to about age 45. Duke Leopold III of Austria (1351-1386) was born when his mother Joanna of Pfirt (c. 1300-1351) was reportedly 51.
The ability of a woman to bear children tends to decrease greatly years before menopause. Woman usually reach menopause and loose the ability to bear children between ages 49 and 52. The oldest known mother to conceive naturally was Dawn Brooke at the age of 59, while the oldest known woman to give birth was 66 years and 358 days.
https://en.wikipedia.org/wiki/Pregnancy_over_age_50
http://memory-alpha.wikia.com/wiki/Keiko_O'Brien
It is not known if theTalosians had equivalent assisted reproductive medicine for Humans available.
If Vina was aged 30.0 to 60.0 at the time of the crash she would be aged about 47.0 to 79.0 in "The Cage" and about 60.0 to 94.0 in "Menagerie".
When the Talosians showed Pike Vina's "true form" she had white hair and looked like she was already too old to have much chance to reproduce, let alone 13 more years later in "Menagerie".
Of course that is assuming that Vina was still capable of reproducing after the crash in the first place.
There are an almost infinite possible speculative reasons for the return of Pike to Talos IV.