The disease is associated with abnormal levels of norepinephrine and estradiol, hormones that are known to help regulate the immune system.

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The levels of estradiol from the patch are about 60 percent higher than in women taking the typical oral contraceptive pill, she says.

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The FDA's Dr. Florence Ho says the agency and Ortho McNeil began studying estrogen and a related chemical estradiol about a year and a half ago.

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These hormones include cortisol (which is related to stress), estradiol (the main female sex hormone) and prolactin (which, as its name suggests, triggers her breast tissue to develop the ability to secrete milk).

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The men in these couples, she discovered, exhibited significant changes in their levels of cortisol, testosterone (the principal male sex hormone, and thus in some sense the masculine equivalent of estradiol) and prolactin over the courses of their partners' pregnancies.

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