It's found a line of relationship between your stress and the small chance of getting children. Even the percentage decreases to 40 percent if you experience stress.
You'll be easy to stress when knowing you're pregnant, especially if you're a career woman.
This study is psychological. It means it depends on how your psychology is. If you're not stressful and don't experience other psychological problems, you can see a doctor to consult because it could be a matter of your fertility.
So don't be discouraged if you've not been blessed with a child because all above is scientific. Just in case, try not to be too stressed.