STRESS has often been blamed for miscarriages in early pregnancy, despite a lack of good data. Now a study of women in rural Guatemala has provided the first evidence that high levels of the stress hormone cortisol do indeed cause early miscarriage.
Pablo Nepomnaschy at the National Institute of Environmental Health Sciences in Triangle Park, North Carolina, and his colleagues followed 61 women for a year. Most of the women were in their early 20s and all had had at least one infant who they were still breastfeeding. The mothers were poor, did not get enough to eat and were often sick.
Three times a week the women collected samples of their urine which were analysed for evidence of pregnancy and for cortisol levels. During the study, there were 22 pregnancies, nine of which were carried to term.
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The researchers found that women whose cortisol levels significantly increased over their baseline were 2.7 times as likely as other women to miscarry. Nine out of 10 pregnancies in women with elevated cortisol levels ended in miscarriage, compared with only four out of 12 in women with more stable cortisol levels (Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.0511183103).
