A child born into winter will experience summer soon enough unless something bad happens. I’m certainly not an expert on babies and their development, but I’d think it matters little. A more interesting topic might be the pregnancy - fetal development sets the course for the next few years or even decades, I’m thinking about epigenetic imprinting. That would certainly have an influence, but since we do not have mating seasons (well, spring and december maybe) I’d wager the impact is comparably low.
How is mainstream media?