It seems clear that the psychological state, not only of the future mother, but also of the couple, influence when conceiving a baby in a natural way, although perhaps in the case of fertilization treatments neither anxiety nor depression affect success of process.
This follows from a study conducted in Holland on more than 400 women under a first fertilization treatment. All answered a questionnaire to assess the level of anxiety and depression, and there was no difference in treatment success between women with high levels and others with "normal" data.
The study authors say they do not want to minimize the importance of psychological well-being in women treated with IVF, but that the conclusions are definitive: anxiety and depression do not affect the probability of becoming pregnant.
Although I believe that the data should be taken with caution, since the researchers themselves say that more extensive studies are needed, and also what should be grouped under the term "stress" should be qualified so that the data is more accurate.
In any case, it is possible that as soon as you know this information, many future moms face calmer a process that often generates anxiety, which is already good news.
