The Adventist Health Study 2 found that very high soy consumption was correlated with changes in female fertility.
Here's a direct link to the abstract of the Adventist Health Study 2's findings on soy consumption and childbearing:
http://www.ncbi.nlm.nih.gov/pubmed/24741329
Quoting the Adventist Health Study 2:
"In women with high (≥40 mg/day) isoflavone intake (12% of this group of women), the adjusted lifetime probability of giving birth to a live child was reduced by approximately 3% (95% CI: 0, 7) compared to women with low (<10 mg/day) intake. No relationships were found between the isoflavone intake and parity or age at first delivery in parous women. A similar inverse relationship (P=0.03) was found between the isoflavone intake and the risk of nulligravidity with a 13% (95% CI: 2, 26) higher risk of never have been pregnant in women with high (≥40 mg/day) isoflavone intake. These relationships were found mainly in women who reported problems becoming pregnant."
So, in this study, women who consumed more than 40 mg/day of isoflavones were 3% less-likely to ever give birth to a live child, and 13% less-likely to ever give birth.
But wait though - how much isoflavones are actually found in the soy foods that we love? Here's the USDA's published data for the isoflavone content of dozens of foods, per 100 grams (3-1/2 ounces):
http://www.ars.usda.gov/SP2UserFiles/Place/80400525/Data/isoflav/Isoflav_R2.pdf .
Soy hot dog: 1.00 mg isoflavones per 100 grams (PDF page 26)
Morningstar meatless chicken patties: 4.40 mg isoflavones per 100 grams (PDF page 21)
Soy burger: 6.39 mg isoflavones per 100 grams (page 32)
Soy drink (soymilk): 7.85 mg isoflavones per 100 grams (page 25)
Soy cheese: 25.72 mg isoflavones per 100 grams (page 25)
Tofu: 13 - 35 mg isoflavones per 100 grams (depending on type)(pages 31-32)
Tofu, salted and fermented: 41.85 mg isoflavones per 100 grams (page 32)
Soy yogurt: 33.17 mg isoflavones per 100 grams (page 27)
Tempeh: 60.61 mg isoflavones per 100 grams (page 30)
Soy protein drink: 81.65 mg isoflavones per 100 grams (page 26)
You can eat certain soy products every day, and never come NEAR the 40 mg/day intake of isoflavones that the Adventist Health Study suggested caution towards.