A recent survey of women found that myths about the causes of miscarriage are still firmly with us. See, the majority of miscarriages are the result of genetic or chromosonal abnormalities with the fetus, hormonal issues, or problems with the uterus or placenta. Of course alcohol and drugs are factors in some cases, but for the most part, we're talking about straight-up medical issues, beyond anyone's control. However, a good third-plus of the women surveyed thought that a pregnant woman's bad mood could negatively affect her baby. I'm living proof here that foul moods do not prevent mothers from carrying babies to term. 

Couple of other myths for you: "One in four of these women thought a pregnant woman's exposure to upsetting situations could hurt her unborn child, and one in five believed excessive exercise could cause a woman to miscarry." The tendency to believe in folkloric miscarriage stories was linked more to the respondent's education level than anything else, and luckily those who had experienced pregnancy loss were more likely to disbelieve the myths, indicating that they probably got some education on the issue through their experiences. While survey folks did not specifically assign blame to the moms in cases of miscarriage (Only "ten percent suggested pregnant women are responsible for their miscarriages, and 3 percent said mothers should be blamed for their babies' birth defects") there is something to the fact that people were willing to peg stress, upsetting situations, and bad moods as causes of pregnancy loss. Here, I'll say it loud, one more time: The miscarriage was not your fault.