Asthma link to pregnancy stress
Women who are stressed in pregnancy may raise the risk of their child developing asthma or other allergies, research suggests.
Ref. https://news.bbc.co.uk/1/hi/health/7404391.stm
I think overly stressed pregnancies lead to many issues with baby and is why in days of old the rich pampered the pregnant. I do think there is truth to this and is why we need to be careful to exercise and eat right to help reduce the effect of negative stress.
Too much stress for the mother affects the baby through amniotic fluid. If the mother is stressed over a longer period of time during pregnancy, the concentration of stress hormones in amniotic fluid rises, as proven by an interdisciplinary team of researchers. Short-term stress situations, however, do not seem to have an unfavorable effect on the development of the fetus. Source 3z.