Can stress cause preterm birth when your pregnant?

Stress. There is some evidence that stress can contribute to preterm labor but as a single cause this would be unlikely. 1 in 10 pregnancies are preterm and the exact cause is not known. Hope this helps.
Absolutely! There is no question that sustained and/or severe maternal stress can trigger preterm labor and birth - and we now know of the actual biochemical pathway involved in these cases (crh, maternal-fetal hypothalamic-pituitary-adrenal axis activation and placental production of excess estrogen with decrease in progesterone). That is why pregnant women should try to maintain their cool and optimism!