Pregnancy can cause pruritus. There are major endocrine changes in women during pregnancy. Early in pregnancy the ovarian corpus luteum produces oestrogen, which changes to oestrogen synthesis by the placental unit after 10 weeks of gestation. By the end of pregnancy, the value of estriol can be 1,000 times higher than that of a non-pregnant woman, and the value of estradiol and estrone 100 times higher than that of a non-pregnant woman; at the same time, the progesterone in the blood of the pregnant mother also rises. These hormonal changes may lead to itchy skin at the base of the thighs.
In addition, increased oestrogen can cause cholestasis in the liver, resulting in pruritus of pregnancy, with jaundice in some patients, often at the end of pregnancy, but also in early pregnancy; in most patients the pruritus and jaundice may abate or heal on their own after delivery.