Without randomized controlled trials, which really aren’t possible here, we can’t know for sure what is causing many miscarriages not involving chromosomal abnormalities. We have a great deal of information about what is associated with them, but that is not the same.

A woman who has health problems in general is more likely to suffer early pregnancy loss than one who does not. Women with high blood pressure, diabetes and thyroid disease are at higher risk. So are those who have hormone problems, immune disorders or infections.

Circumstances at work can be associated with miscarriages. A 2013 systematic review found that working nights was a risk factor, as were things like working in a three-shift schedule, working 40 to 52 hours per week, and standing for six to eight hours per day.

Smoking has been associated with an increased risk of miscarriage, according to a meta-analysis that included 98 studies. Obesity has also been linked to recurrent miscarriage.

To be clear, there is no evidence that any of the factors I’ve mentioned causes a miscarriage. All of these data arise from observational studies that investigate associations, not causes. It’s easy to make an erroneous leap from one to the other. Smoking, obesity and night-shift work are each associated with being poorer and having fewer resources for health. This probably wouldn’t stop some people from quickly blaming women for their choices rather than considering their socioeconomic status.

Ask almost any medical professional what caused a miscarriage, especially one early in pregnancy, and — other than chromosomal abnormalities — they will say that “we do not know.” If medical professionals cannot make that determination, it’s hard to understand how someone in law enforcement might.

A bigger concern is that a fear of becoming part of an investigation may cause women to avoid medical care. Women who are bleeding or are heading toward septic shock may not come to the emergency room or doctor’s office. They could die. This would only increase America’s maternal mortality rate, which is already much higher than that of most other advanced nations.