Intense pain could be a sign of early miscarriage or ectopic pregnancy.

强烈的疼痛可能是早期流产或宫外孕的征兆。

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But she kept the news secret because she feared a miscarriage in the early weeks of pregnancy, Jonsson wrote in her News of the World column.

BBC: Ulrika Jonsson and Lance Gerrard-Wright

There are also some findings showing that stress can increase the likelihood of miscarriage but because so many early miscarriages go undetected, they are more difficult to study and data is not easily available.

BBC: Earthquakes 'trigger early births'