Pregnancies stop developing on their own, usually associated with a genetic (chromosomal) abnormality that none of us can do anything about, an extra or missing chromosome that the developing pregnancy inherited from the egg or sperm that created it.
And built into our contract as human beings is the stipulation that 12-15% of our pregnancies will stop their own development sometime between the missed period and the end of the first trimester, most often between 4 and 8 weeks of pregnancy (counting from the first day of the last period.)
And there is nothing magical about the time of the missed period. In many cycles the sperm will fertilize the egg and implant in the wall, but will stop development after a few days or a week. The lining, no longer getting the hormonal signals that result from HCG release, will slough off the way it always does.
If it‘s before the expected period we say there was no pregnancy. If it is a couple of weeks later we call it a miscarriage.
Nothing comes in and stops the pregnancy, not an argument or a fall or stress or an orgasm or not realizing that the cough syrup has alcohol in it.