Soya or soy is a common protein substitute, particularly for vegetarians or vegans. Most people have it in the form of soy granules, soybean oil, soya flour or soy milk. There’s been conflicting research on soy’s impact on male and female fertility.
Why are some experts worried? It’s because phytoestrogens (the plant form of estrogens) are naturally found in soybeans and are similar to the female hormone estrogen. This additional estrogen activity can create an estrogen-progesterone imbalance that could impair hormone function, egg production, and ovulation. Soy may lower sperm count in men.
In India, the US & many countries, soyabean is a GM food or genetically modified. GM foods can affect sperm motility & morphology, and in women, an increased inability to get pregnant.
Until definitive conclusions can be reached, I’d recommend avoiding soy-based foods when you’re trying to get pregnant. If you must have soy, then fermented soy like miso or tempeh is fine. A little amount of soy sauce to flavor food occasionally is also ok.