Some skin changes during pregnancy are not necessarily skin conditions, but rather physiological changes that do not require treatment

Pregnancy can cause a range of physiological changes in the skin, hair, and appendages such as nails, and it is important to recognize these changes to avoid confusion with true skin conditions. These physiological changes can be divided into the following categories (tables).

Physiological changes in episkin, hair, and nails

Hyperpigmentation

Changes in hair and nails

Melanoma

Changes in blood vessels

Expansion lines

Activity of the acroplasmic/exocrine glands

Gestational pruritus

Immune skin changes

1, Pigment adhesion

About 90% of pregnant women develop local or generalized pigmentation, and the darkening of skin tone is more significant than that of light-skinned pregnant women. The most common part is a darkening of the lower abdomen and the mid-abdomen line; This is listed in obstetric textbooks as an early change in pregnancy. However, this may not be noticeable in the first few months of pregnancy, especially in the first pregnancy. The blackened midline extends from the pubic symphysis to the umbilicus and may extend upward to the xiphoid process. Recurrence occurs earlier than in first-time pregnancies.

Pigmentation also occurs in the nipples and areolas, as well as in the external genitalia and armpits. Some women have a darkening of the neck, which bothers them a lot, but like other changes in pigmentation during pregnancy, these pigments gradually fade after delivery. Stretch marks ("stretch marks") are common, and in sensitive individuals, stretch marks, like other scars, moles and spots, become darker and fade after childbirth. Vulvar melanosis can also occur during pregnancy, and increased melanin production is thought to be due to elevated levels of a- and B-melanocyte-stimulating hormone (MSH), -1.

Some darker-skinned people (both men and women) have a pigmentation line (also known as a Voigt or Futcher line) on the outside of their upper arms and/or the back of their legs, a phenomenon that is often not detected during pregnancy when pigmentation throughout the body makes it more pronounced.

2. Black spot disease

Melasma (formerly known as melasma or "pregnancy spots") is symmetrical patchy hyperpigmentation on the face.

Depending on the distribution of pigmentation, it can appear in three forms: in the center of the face, on both sides of the cheeks, or in the mandible. Although buccal melanolakia is the most typical, most patients are affected throughout the face, including the forehead, Chen, upper lip, nose, and jaw. Three-quarters of pregnant women develop melanoma in the second trimester, and one-third of these women have taken oral contraceptive pills (OCP). Meloplakia is thought to be caused by hormonal changes that can be exacerbated by sun exposure and often resolve after pregnancy or one year after stopping oral contraceptives. Histologically, excessive melanin deposition may be seen in epidermal or dermal macrophages.

Lesions persist in about 30% of patients, whether caused by pregnancy or the use of estrogen-containing oral contraceptives. Postpartum, epidermal pigment (which can be made visible by the Wood lamp test) is best treated with topical hydroquinone ointment and tretinoin. Treatment during pregnancy should include using a sunscreen with a high SPF and avoiding ultraviolet rays.

3. Swelling lines

Almost all pregnant women develop stretch marks, also known as stretch marks, in the second and third trimesters of pregnancy. Striae distense are linear, pink-colored atrophic streaks that appear on the abdomen, breasts, buttocks, thighs, and groin perpendicular to the skin tension line. The same striae can also be seen in Cushing syndrome, steroid therapy, and rapid weight changes. Stretch marks are rare in black and Asian women and may run in families. The typical red streaks gradually change to a complexion or grayish-white over time (with or without various ointments), and although the postpartum atrophic lines may become thinner, they do not disappear completely. The efficacy of topical tretinoin ointment 0.1% or 0.025% is controversial, and conclusions have been reported in the literature. Retinoids are contraindicated during pregnancy and their use may also cause irritation.

4. Changes in hair and nails

Body hair overgrowth is visible in most pregnant women, and this is more pronounced in women with darker skin tones and/or more body hair. This phenomenon is thought to be due to an increase in androgen production by the ovaries during pregnancy. The numerous short soft hairs give the skin a "hairy" appearance, which disappears after childbirth with the onset of resting effluvium. If significant hirsutism persists postpartum, polycystic ovary syndrome and androgen-secreting ovarian tumors should be considered. Treatment is done to reassure the patient that cosmetic hair removal treatments (such as hair removal creams, electrolysis or ruby laser treatments) can be performed postpartum if necessary.

Resting phase hair loss can lead to hair loss about 1~5 months after childbirth, and it can last for 1 year or more before new hair regrowth. The best explanation for this phenomenon is that pregnancy affects the normal hair loss cycle, keeping more hair in the anagen phase during pregnancy. Until childbirth, the hair grows thicker because the amount of hair that enters the resting (shedding) phase decreases. After childbirth, hair follicles quickly return to their normal hair loss cycle, resulting in excessive hair loss. In most patients, this hair loss is uniform, but a few can occur only in the parietal forehead, which resembles male alopecia, but the patient does not develop baldness.

Nail changes usually begin in the first trimester and can be seen as brittle, soft, and growing faster. Transverse and longitudinal grooves and distal nail detachment of the nail may also be seen during pregnancy, but the mechanism of these changes is unknown. In addition, there have been reports of longitudinal black nails.

5. Vascular changes

During pregnancy, a woman's vascular system undergoes noticeable changes to adapt to the fetus and its growth. Maternal blood volume, vasodilatory, capillary permeability, and neovascularization were significantly increased. Purulent flesh may occur at the site of the mucosa or on the fingers (toes).

Bud swelling. Nearly half of pregnant women develop varicose veins, especially in the perianal area (hemorrhoids) and legs, and edema of the legs and ankles is common, with swelling of the hands and eyelids. Varicose veins and swelling in the legs can be relieved by elevating the lower extremities and wearing compression stockings. Patients should also try to avoid standing or sitting for long periods of time.

Spider hemangiomas (spider angiomas) are common in the first and second trimesters and can appear in the upper part of the trunk with erythema in the center with radial branches, which are easily identifiable and can be seen in two-thirds of pregnant white women. Anthurium is also more common and can occur in the same proportion of patients, mostly in large or small thenars. The mechanism of their occurrence is unclear and is thought to be related to estrogen or angiopoietic factors. These changes usually disappear after childbirth. Unilateral nevus telangiectasia syndrome is a collection of epidermal spider angiomata, mostly on the face and neck, and can occur during pregnancy, alcoholic liver disease, and oral contraceptive therapy.

6. Exocrine gland/parietal secretory gland activity

Increased activity of exocrine glands during pregnancy, which can lead to increased hyperhidrosis and dyshidine eczema; However, the activity of the acrosoma secretory glands is reduced, so Fox-Fordyce disease (prurigo rash of apocrine glands) and hidradenitis suppurativa are often resolved. The activity of the sebaceous glands is also enhanced, especially in the third trimester, which can lead to acne development and exacerbation. The rate of sebum secretion increases during pregnancy and returns to normal postpartum. In the first trimester, 30%~50% of pregnant women can see brown papules on the areola, namely Montessori nodules, which are caused by sebaceous gland hyperplasia and disappear after childbirth.

7. Changes in the immune system

During pregnancy, the mother's immune system will undergo some important changes in order for the fetus to survive. These changes are also responsible for the effects of pregnancy on the skin and the increased susceptibility of pregnant women to certain skin diseases during pregnancy.

Th2 (CD4+ cell subtype) cytokines are associated with antibody responses, suggesting that Th2 cytokines dominate the regulation of maternal immune responses. A variety of interleukins (IL-3, IL-4, IL-5, IL-10, and IL-13) are Th2 cytokines. Animal studies have shown that these cytokines are detectable in placental tissue throughout pregnancy. IL-10 inhibits Th1-mediated cellular immunity. Intraplacental conversion from Th1 to Th2 cytokines allows the fetus to tolerate and survive. There is also negative feedback so that Th2 cytokines can inhibit Th1 cytokine production.

Thus, the immune response during pregnancy is primarily the production of antibodies rather than cell-mediated immune responses, which allows the fetus (allograft) to survive and avoid rejection. This may be the reason for the marked increase in the incidence of autoimmune skin diseases and skin infections during pregnancy. Improvements in psoriasis (Th17-mediated) and atopic eczema (Th2-mediated) exacerbations that are common during pregnancy also stem from these changes in the immune system.

Sources:

Obstetrics and Gynecology Dermatology.