Progesterone, in contrast to estrogens, is mildly catabolic in humans, and tends to increase appetite. Progesterone also elevates basal body temperature. This is not a consequence of increased anabolism or stimulation of the thyroid but appears to involve a direct action on the areas of the hypothalamus concerned with thermoregulation. This rise in temperature occurs only after ovulation and thus is only useful as a basis for establishing the regularity of a woman's cycle if the rhythm method of contraception is contemplated. Progesterone also shows some affinity for aldosterone receptors in the kidney. However, after binding by progesterone, the receptor is not activated and natriuresis ensues. This results in a compensatory rise in aldosterone output to restore sodium retention. Sodium retention may also be enhanced in the luteal phase of women by a direct stimulatory effect of luteal estrogen on angiotensinogen production. As a consequence of these events in some women there may be a net retention of sodium and water (i.e., weight gain) toward the end of the luteal phase, which contribute to some symptoms characteristic of the premenstrual period, for example, heavy, tender breasts.