Prince Harry blamed a British tabloid for Meghan Markle's miscarriage. Here's what we know about the link between pregnancy loss and stress.

• Prince Harry said he believes The Mail on Sunday caused Meghan Markle's miscarriage due to stress.
• Stress is not a direct cause of miscarriage, but some studies find a link between the two.

In the sixth and final episode of the Netflix docuseries "Harry & Meghan," Prince Harry said he suspects Meghan Markle's 2020 miscarriage was caused by the stress of Meghan's lawsuit against the British tabloid The Mail on Sunday.

The privacy case, which Meghan eventually won, was about the publication of a letter to Markle's estranged father.

"I believe my wife suffered a miscarriage because of what The Mail did," Harry said in the episode.

"I watched the whole thing. Now, do we absolutely know that the miscarriage was created, caused by that? Course we don't," he said.

"But bearing in mind the stress that it caused, the lack of sleep and the timing of the pregnancy, how many weeks in she was, I can say from what I saw, that miscarriage was created by what they were trying to do to her," he added.

Stress is not a direct cause of miscarriage, which is most often the result of chromosomal abnormality that interferes with an embryo's development, according to the Mayo Clinic.

Often, there's nothing a pregnant person can do to prevent miscarriages, which occur in at least 20% of pregnancies.

There is some evidence suggesting an association between stress and miscarriage. One 2017 meta-analysis, for instance, found a 42% increase in miscarriage risk in women who'd experienced psychological stress like financial or marital problems, death, divorce, abuse, and work stress.

The findings held even when other related factors, like health behaviors, were accounted for.

The study authors say this link may be explained, at least in part, by how stress impacts hormones. An earlier study, for one, showed that stress triggers a hormone that's also involved in contractions.

But the authors also caution that studies on miscarriage and stress are faulty, usually relying on women's self-reports and unable to rule out all confounding factors.

Pregnant people with unstable housing, poor access to healthcare and little social support, for example, are likely to both feel stressed and have less healthy pregnancies.

What is clear is that unhealthy coping mechanisms to stress, like drugs, cigarettes, alcohol, or over- or under-eating, can increase the risk of miscarriage.