The reduction in androgen and increase in estrogen will result in a skin that is overall thinner and more translucent ("lighter", see through effect) due to loss in dermal (deeper layer of skin) thickness. But, estrogen as opposed to androgen, make the epidermis, the upper layer of the skin, thicker.
Also from
Volume 64, Number 1
OBSTETRICAL AND GYNECOLOGICAL SURVEY
Copyright © 2009
by Lippincott Williams & Wilkins
Physiological Changes Associated with the Menstrual Cycle
A Review
"The effects of estrogen on pigmentation were first implied by observed changes in pigmentation characteristic of pregnancy: patches of increased pigmentation on the face known as chloasma, as well as darkening of the skin of the areolae, the perineum, and the skin over the linea alba, which fade shortly after delivery (29). Application of estrogen-containing ointment to children results in hyperpigmentation, when applied to the genital area as well as the nipples and linea alba (33). Hyperpigmentation is also observed in some patients with use of oral contraceptives (20)"
"The increase in pigmentation was reported to be most noticeable under the eye (29)."
This is why you may notice freckles where before there was none and dark patches in some areas of the body, especially after exposure to the sun.