So this was not the true birth of Jesus Christ .. the true birthday was in Autumn .. the time of cutting the date-clusters in Palestine .. In Iraq, the cutting of the date bunches is usually in November .. when the date is ripen, and before the season of the rain falling .. when the rain falls, the date fruit will corrupt and will be useless.
Quran 19: 22-33, which mean:
(22. "So she conceived [Jesus], and withdrew with him to a remote place [away from people, in order to give birth of him .]
23. And the labor pains drove her to the trunk of a palm-tree [to recline on it in the delivery]; she said [then]: "Would that I had died before this [incident]; would that I had been something forgotten."
24. And [when she gave birth to him, Jesus] called to her from below her: "Grieve not; your Lord has made beneath you[r feet] a flowing [water] stream."
25. "Shake the trunk of the palm-tree k toward you, and it will let fall on you culled l fresh dates."
26. "Eat, therefore, [of the fresh date], drink [of the stream water], and be comforted [and don’t fear of disgrace.]
But should you see any mortal [who may ask you about me], say [to him by signals]: "I have vowed to [God] Most Gracious a fast [of silence from speaking]; I will, therefore, not speak this day to any human being")
25 k Which is at your side.
25 l Because it was Autumn, and it was the time of cutting the date-clusters; so when they culled its date, some dates fell on that hut, and when she shook the trunk, some dates which were on the hut fell which Mary took and ate.
More explanation is in the link: