I think there is a difference, but there is no limit to the amount of research and hypotheses about what affects pregnancy. A pregnancy typically lasts long enough to gain some seasonal exposure at some point. If you were concerned about having immunodeficiencies due to a long winter, you should ingest locally sourced honey. Since they gather pollen from neighboring flowers, you’re inoculated to allergen-causing plants (as is the baby, theoretically).

More moxie, a refined taste for pizza, knowledgeable on driving aggressively or defensively, heightened tolerance for crowds and smells.

Biodiversity is fairly simple to achieve in suburbia. Most subdivisions have vegetated stormwater infrastructure, like roadside ditches. Having flowering groundcover like clover in the planting plan, allowing native plants to propagate and act like a “meadow,” using various practices (Integrated Pest Management) to control invasive plants, and avoiding mowing during the peak blooms all make a huge difference.

Note too that stormwater systems are generally the connected spaces which allow for animals like frogs and invertebrates to travel. There’s some threat of these ponds turning into ecological traps, but if you build it, they will come. Imperfect habitat is better than no habitat.

Edit: I’ll add that one of the best ways to make a difference is to keep a native wildflower seed blend on-hand (I use spice jars on my belt) and sprinkle/smush onto dirt patches in urban areas. If your plants are native and appropriate for the exposure, you’ve created a little gas station for migrating pollinators.