Maternal physiologic adaptations

Physiologic changes in the skin and its appendages during pregnancy and the postpartum period include alterations in pigmentation; connective and cutaneous tissue; integumentary vascular system; hair, nails, and secretory glands; and pruritus. Some integumentary alterations regress completely during the postpartum period; others recede but never completely disappear. Most of these alterations are secondary to the hormonal changes of pregnancy.

Antepartum period

The basis for changes in the skin, hair, and secretory glands during pregnancy are thought to be hormonal—especially the effects of estrogens and adrenocortical steroids. Similar alterations are often seen in women using oral contraceptives. There is a familial tendency or genetic predisposition for some of the cutaneous and vascular changes.^77,118

Alterations in pigmentation

Alterations in pigmentation are common during pregnancy and include hyperpigmentation of specific areas of the body and melasma (chloasma). In early pregnancy, hyperpigmentation is thought to be due to the effects of estrogens and progesterone on melanocytes. This finding is also consistent with reports of alterations in pigmentation associated with use of oral contraceptives.³¹ Progression is also thought to be related to the effects of placental corticosteroid-releasing hormone and of pro-opiomelanocortin peptides such as adrenocorticotropic hormone (ACTH), melanocyte-stimulating hormone (MSH), β-endorphin (see Chapter 19), and possibly placental lipid stimulation of tyrosinase (enzyme involved in production of melanin).^{77,85,90,93,96}

Hyperpigmentation.

Hyperpigmentation is the most frequent integumentary alteration during pregnancy. Changes in pigmentation are seen in up to 91% of pregnant women, tend to be more frequent in women with dark hair or complexions, and are progressive throughout pregnancy.⁶² Most women experience a mild, generalized increase in pigmentation that is especially prominent in areas of the body that tend to be naturally more intensely pigmented. These areas include the areolae, genital skin, axillae, inner aspects of the thighs, and linea alba.^{23,28,61,77,93}

The linea alba is a tendinous median line that extends along the anterior of the abdomen from the umbilicus to the symphysis pubis and occasionally superiorly to the xiphoid process. Hyperpigmentation during pregnancy causes the linea alba to darken and become the linea nigra. Up to one third of women on oral contraceptives also develop a linea nigra. Pigmentary changes tend to fade during the postpartum period in fair-skinned women, but some pigmentary changes may remain in women with darker skin and hair. Hyperpigmentation may be exacerbated by sun exposure.^28,61,93,96

Freckles, nevi, and recent scars may darken during pregnancy, perhaps due to an up-regulation of receptors for estrogens and progesterone on the nevus cell surface.²⁷ Existing melanocytic nevi may increase in size or new nevi may develop during pregnancy, although some have reported that existing melanocytic nevi do not change significantly during pregnancy.⁵⁷ Increased malignant degeneration of nevi is not seen during pregnancy.^57,85 Prophylactic removal of nevi following pregnancy may be considered. Any nevi showing signs suggestive of malignancy should be excised.^28,61,93,96

Although rare, some women may develop pigmentary demarcation lines, which are areas of hypopigmentation that follow the distribution of peripheral cutaneous nerves, and disappear after delivery. The lines are thought to be due to prolonged uterine compression of these nerves, particularly at S1-S2, leading to a sharp demarcation between pigmented and hypopigmented areas.^2,89,93

Melasma.

Melasma (also known as chloasma or the “mask of pregnancy”) is a common occurrence in pregnant women.^{5,15,77,93,96} Melasma is characterized by irregular, blotchy areas of pigmentation on the face, usually bilateral and symmetrical and seen most commonly on the cheeks, chin, and nose.⁷⁷ The areas of altered pigmentation are not elevated and can range in color from light to dark brown. Three distribution patterns have been described: centrofacial (63%), involving the cheeks, forehead, upper lip, nose, and chin; malar (21%), over the cheeks and nose; and mandibular (16%), over the ramus of the mandible.⁵ Three histological patterns have also been identified: epidermal (increased deposition of melanin in the melanocytes of the basal and suprabasal layers), which is seen in 70% of women; dermal (macrophages with large amounts of melanin can be found in both the papillary and reticular layers of the dermis), which is seen in 10% to 15%; and a mixed form, which is seen in 2%.^5,61 Although these pigmentary changes tend to fade completely within 1 year following pregnancy, they may persist (especially in dark-haired individuals).^63,93,96

Melasma is associated with increased expression of α-melanocyte stimulating hormone in the involved skin area.⁹³ There is a genetic predisposition toward development of melasma.^5,100 Melasma is seen most frequently in women with dark hair and complexions, is exacerbated by the sun, and tends to recur (often with increased intensity) in subsequent pregnancies or with use of oral contraceptives.¹⁰ Melasma has also been reported occasionally in nonpregnant individuals who are not on oral contraceptives or other hormonal medications.^54,93,96,118

Avoidance of sun tanning during pregnancy, use of hats to avoid facial exposure to sun, and use of sunscreens with sun protective ratings greater than 15 may reduce the severity of melasma (Table 14-1). Because melasma often fades spontaneously following pregnancy, treatment is generally limited to the less than 10% of individuals with persistent pigmentation postpartum.⁷⁷ Various depigmenting formulas have been developed to treat persistent melasma, with varying success. These formulas tend to be relatively effective on epidermal-type melasma but have little effect on the dermal type. Treatment may need to be continued for 5 to 7 weeks before satisfactory results are achieved. Topical 2% to 5% hydroquinone with or without retinoic acid and corticosteroids has also been used postpartum, again with varying success. This treatment can result in complications such as hypopigmentation, hyperpigmentation, and contact dermatitis.^{5,10,93,96,118}

Table 14-1

Nursing Management for Common Problems during Pregnancy Related to the Integumentary System

ALTERATION	INTERVENTION
All alterations	Provide anticipatory teaching regarding appearance of alteration. Counsel regarding basis for alteration and course. Evaluate effect on body image and relationship with partner and provide counseling.

Hyperpigmentation

Avoid suntanning during pregnancy and use broad-spectrum (protective factor greater than 15) sunscreen.

Use nonallergenic cover-ups.

Melasma

Avoid suntanning during pregnancy or when using oral contraceptives.

Use broad-spectrum sunscreen (rating of 15 or greater).

Use nonallergenic cover-ups.

Counsel regarding the risk of similar changes with oral contraceptives.

Counsel regarding alternative methods of birth control.

Counsel regarding use of sunscreen and protection from sun with sunscreen use following pregnancy.

Striae gravidarum

Use topical emollients or antipruritics as required.

Use supportive garments for breasts and abdomen.

Spider nevi Nonpitting edema Varicosities Increased eccrine gland activity Pruritus

Changes in connective tissue

Striae gravidarum (also called linear striae, striae distensae, or linear stretch marks) are linear tears in dermal collagen that are commonly seen during pregnancy. These markings initially appear as irregular, pink or purple, wrinkled linear streaks that gradually become white. Striae are most prominent by 6 to 7 months and occur in 50% to 80% of pregnant women.⁹³ They appear initially over the abdomen oriented in opposition to skin tension lines and later on the breasts, thighs, and inguinal area. Striae are seen more frequently in younger women with greater total weight gain during pregnancy, obese women, and women with larger birth weight infants.¹² In addition, there appears to be a familial tendency.^{5,77,86,93,111,118}

Striae gravidarum usually fade following pregnancy but never completely disappear, remaining as depressed, irregular white bands. Some women report striae itching, although because both pruritus and striae formation are prominent over the abdominal area during pregnancy, these two phenomena may not be related. There is no effective treatment to prevent striae formation. Topical emollients and antipruritics may be used (see Table 14-1). However, the effectiveness of topical agents such as cocoa butter, vitamin E, tretinoin, and olive oil and of massage to prevent striae formation has not been substantiated in controlled studies.^{77,96,102,120} Two recent studies found that cocoa butter did not prevent striae gravidarum or reduce its severity.^12,87

Striae gravidarum are believed to arise from hormonal alterations—especially of estrogens, relaxin, and adrenocorticoids—along with alterations in the dermal support matrix with stretching.⁸⁷ The increased levels of estrogens, corticosteroids, and relaxin relax the adhesiveness between collagen fibers and foster formation of mucopolysaccharide ground substance, which causes separation of the fibers and striae formation. The increased glucocorticosteroids during pregnancy may decrease dermal fibroblasts and collagen synthesis. Mast cells, which contain hormonal receptors for estradiol, also increase. Mast cells release enzymes to lyse collagen.^{5,61,96,102,118}

Vascular and hematologic changes

Vascular changes during pregnancy related to the integumentary system include development of spider nevi or angiomas, palmar erythema, nonpitting edema, cutis marmorata, purpura, hemangiomas, and varicosities. Purpura and scattered petechiae may be seen on the legs of some women and are due to decreased capillary integrity with increased hydrostatic pressure.⁵ These usually resolve postpartum. Vascular changes are a result of distention, instability, and proliferation of blood vessels mediated by changes in pituitary, adrenal, and placental hormones with increased release of angiogenic growth factors.^61,63,96 Other alterations in the vascular and hematologic systems are described in Chapters 8 and 9.

Vasomotor instability.

Vasomotor instability during pregnancy may result in flushing, feelings of hot or cold, and cutis marmorata.^5,44,89 Cutis marmorata is a transient bluish mottling of the legs that is exaggerated on exposure to cold. It arises from vasomotor instability secondary to elevated estrogens. Persistence postpartum is abnormal and may suggest underlying pathology such as collagen vascular disorder, systemic lupus erythematosus, or vasculitis. Other changes due to vasomotor instability during pregnancy include pallor, facial flushing, and heat and cold sensations. Purpura secondary to increased capillary fragility and permeability occurs during the last months of pregnancy in many women.^96,118

Spider nevi.

Spider nevi (also called spider angiomas, spider telangiectases, or nevus araneus) are found in 10% to 15% of normal adults, in individuals with liver dysfunction, and in up to two thirds of pregnant women. These nevi are more common in white pregnant women (60% to 70% by term) than African-American pregnant women (10% by term).⁴⁴ Spider nevi consist of a central dilated arteriole that is flat or slightly raised with extensive radiating capillary branches. They are most prominent in areas of the skin drained by the superior vena cava (i.e., around the eyes, neck, throat, and arms). The basis for formation has been related to increased estrogen, because these structures are seen more frequently both during pregnancy and with use of oral contraceptives. However, many individuals with spider nevi associated with liver disorders do not have elevated estrogen levels.^61,118

Spider nevi generally appear between 2 and 5 months of pregnancy and may increase in size and number as pregnancy progresses. These structures tend to regress spontaneously and fade within the first 7 weeks to 3 months following delivery, although they rarely completely disappear. They may recur or enlarge during subsequent pregnancies. Unresolved spider nevi can be treated by pulse-dye laser or electrodesiccation therapy.⁹³

Palmar erythema.

palmar erythema is seen with pregnancy, liver disease, estrogen therapy and collagen vascular diseases.⁹³ Two patterns of palmar erythema are seen during pregnancy: erythema of hypothenar and thenar eminences, palms, and fleshy portions of the fingertips; and diffuse mottling of the entire palm. The latter form is more common and similar to changes seen with hyperthyroidism and cirrhosis. Palmar erythema generally appears during the first two trimesters and disappears by 1 week after delivery. This phenomenon has a familial tendency and is seen in approximately two thirds of white pregnant women and one third of African-American pregnant women. Spider nevi and palmar erythema often occur together, suggesting a common etiology generally believed to be elevated estrogen levels with increased skin blood flow.^{5,28,44,61,90,93,118} No treatment is needed. Palmar erythema resolves after delivery.

Nonpitting edema.

Increased vascular permeability and sodium retention due to the effects of estrogens and corticosteroids result in transient nonpitting edema of the face, hands, and feet during late pregnancy.^44,89 In the lower extremities, this is aggravated by pressure from the growing uterus. Nonpitting edema occurs in the face, especially the eyelids in approximately 50% of women, and in the lower extremities in 70% and is not associated with preeclampsia.^96,118 Although most pronounced in the morning, it usually improves during the day. Interventions for non-pitting edema during pregnancy are listed in Table 14-1. Vulvar edema may also be seen.

Capillary hemangiomas.

Pre existing capillary hemangiomas may increase in size during pregnancy.^5,96 In up to one third of pregnant women, new hemangiomas appear by the end of the first trimester, with slight, slow enlargement during the remaining trimesters.^44,118 New hemangiomas usually appear on the head and neck and are unusual elsewhere.⁹⁶ Enlarged existing hemangiomas and new hemangiomas regress postpartum but may not completely disappear. Hemangioma development in pregnancy is related to elevated estrogen.¹¹⁸

Varicosities.

^{5,61,65,89,93,96,118} Varicosities develop in approximately 40% of pregnant women. Varicosities occur most commonly in the legs but may also appear in the pelvic vessels, vulva, and anal area with hemorrhoid formation. Varicosities arise from estrogen-induced elastic tissue fragility, vascular distension, relaxin-weakened collagen and elastin, increased venous pressure in the lower extremities and pelvis from pressure of the gravid uterus, and familial tendency for valvular incompetence. Varicosities generally regress postpartum but do not completely disappear. Thrombi are rare with leg varicosities but are more frequent with hemorrhoids. Hemorrhoids are discussed in Chapter 12.

Alterations in cutaneous tissue and mucous membranes

The most common mucous membrane alterations are changes in the vagina and cervix, which are seen in all pregnant women, and gingivitis, which is seen in many women. A less common oral finding is a cutaneous lesion of the gums known as angiogranuloma, or epulis. Epulis and gingivitis are discussed in Chapter 12. Increased flow to the nasal mucosa leads to rhinitis in up to one third of women.³⁷ Jacquemier-Chadwick and Goodell signs are vascular changes that are early signs of pregnancy. Jacquemier-Chadwick sign is characterized by erythema of the vestibule and vagina; Goodell sign is characterized by increased vascularity of the cervix.^61,63,96

Another cutaneous change during pregnancy is the development of or increase in the number of existing skin tags called molluscum fibrosum gravidarum (also called acrochordons or, if large, fibroepithelial polyps).^5,77,90,96 These are soft, skin-colored or hyperpigmented skin tags, which are small (usually 1 to 5 mm), pedunculated fibromas that appear during the second half of pregnancy, primarily on the lateral aspects of the face and neck, upper axillae, groin, and between and underneath the breasts. The cause of fibromata molle is unknown but is thought to be hormonal. These skin tags are more common in the second half of pregnancy, when they may increase in size and number. These growths may regress or clear spontaneously following delivery, although many remain. Remaining skin tags can be excised.^{61,63,77,90,93,96,118}

Alterations in secretory glands

Activity of the sebaceous, apocrine, and eccrine glands of the skin is altered during pregnancy. Sebaceous gland activity is generally reported to increase during pregnancy.^5,90,118 Many pregnant women report that their skin, especially on the face, feels “greasy.” Some women may develop acne, often for the first time, although women with existing acne may or may not experience worsening of the acne.^5,61 These changes are due to increased ovarian and placental androgens.^61,93 Montgomery tubercles (small sebaceous glands on the areola) enlarge, beginning as early as 6 weeks’ gestation. Changes in Montgomery tubercles and the breasts are described in Chapter 5.

Apocrine sweat gland activity decreases during pregnancy, possibly as a result of hormonal changes.^5,118 Eccrine sweat gland activity increases gradually during pregnancy, possibly because of increased thyroid activity along with increased body weight and metabolic activity.^89,90,118 Because eccrine glands are important (along with the cutaneous blood vessels) in thermoregulation at the skin surface (see Chapter 20), their increased activity reflects dissipation of excess heat produced by the increased metabolic activity of the pregnant woman and her fetus. Increased eccrine activity during pregnancy can lead to miliaria (prickly heat) or dyshidrotic eczema.^5,61,118 Palmar sweating is decreased in pregnancy, even though this is an area where eccrine glands are highly concentrated. The basis for this is unclear but may be related to increased thyroid or adrenocortical activity.^5,28,61 Interventions are listed in Table 14-1.

Alterations in hair growth

Estrogen increases the length of the anagen (growth) phase of hair follicles during pregnancy (see the Hair Loss section under Postpartum Period). This results in increased hair loss postpartum. The diameter of the hair shaft also thickens by late pregnancy in most women.^5,31,83 A mild hirsutism may develop, usually beginning around 20 weeks, with increased growth of hair on the upper lip, chin, and cheeks and in the suprapubic midline. Fine new hairs usually disappear by 6 weeks postpartum, but the coarser hairs usually remain.^{13,61,77,93,96,113,118}

During late pregnancy and the early postpartum period, some women develop hair loss with frontoparietal recession of the hairline similar to changes seen in male-pattern baldness. This loss is rare and is usually associated with complete regrowth and not with later development of female-pattern alopecia.^61,96

Alterations in the nails

Changes in fingernails and toenails during pregnancy are uncommon and of unknown pathogenesis. Nail changes occur as early as 6 weeks and include transverse grooves, increased brittleness, distal separation of the nail bed (onycholysis), whitish discoloration (leukonychia), and subungual keratosis. These changes regress after delivery.^{5,61,77,90,93,118} A faster toenail growth rate has been reported by some women during pregnancy, possibly due to increased peripheral blood flow due to estrogens, along with coarsening of the nail texture.⁸⁹

Pruritus

Pruritus is the most common cutaneous symptom during pregnancy.⁵ The itching may be localized, especially over the abdomen during the third trimester, or generalized. Abdominal pruritus at the end of the first trimester may be an isolated finding or an early sign of intrahepatic cholestasis of pregnancy with or without associated jaundice or one of the other specific dermatoses of pregnancy (Table 14-2). Pregnancy-associated pruritus always clears after delivery but may recur in subsequent pregnancies or with use of oral contraceptives.⁹³ Pregnant women with pruritus should also be assessed for other skin disorders, including pregnancy dermatoses, contact dermatitis, and drug reactions.^5,93,118

Generalized, intense pruritus and erythematous urticarial plaques initially, followed by crops of fluid-filled vesicles and/or tense serum-filled bullae Initially around umbilicus, then spreads over abdomen to chest, back, extremities, palms and soles; rarely involves face Severe forms have been associated with increased incidence of stillbirth, preterm birth, small-for-gestational-age (SGA) infants, and transient neonatal skin lesions; ncreased risks of SGA and preterm infants, probably due to placental insufficiency Impetigo herpetiformis (93, 96, 98) Very rare Small (1-2 mm), sterile, white pustules on irregular erythematous plaques; central pustules become crusted as new pustules develop in periphery of plaque Often appears initially in femoral or perineal areas; spreads to lower abdomen, to medial aspects of the thighs, and around the umbilicus; occasionally involves hands, feet, under nails, and tongue Variable pruritus, associated with hypocalcemia, fever, lethargy, nausea, vomiting, and diarrhea Increased incidence of abortion and stillbirth and possible placental insufficiency Atopic eruption of pregnancy/Prurigo of pregnancy (11, 93, 96, 97, 98) 1/300 Severe pruritus with small erythematous papules that are skin-colored; primary papules may be destroyed by scratching, leaving excoriated crusts as initial presentation Trunk (usually initial presentation) and/or extremities Intense itching None Pruritic urticarial papules and plaques of pregnancy (PUPPP), or polymorphic eruption of pregnancy (PEP) (11, 72, 93, 96, 97, 98) 0.6% of pregnant women (more common in primiparas) Erythematous papules and urticarial plaques with excoriation usually absent Usually appear initially in abdomen, often in striae, then spread across abdomen to thighs, arms, and buttocks; rarely found above midthorax May have mild pruritus None; twice as likely with male fetus or multiple pregnancy Intrahepatic cholestasis of pregnancy (11, 73, 81, 93, 97, 98) 0.02%-2.4% of pregnant women Severe generalized pruritus without any skin lesions, especially on palms and soles, although excoriation may result from scratching; worse at night; 50% have darker urine and stools Pruritus usually begins on abdomen, then spreads to other areas

Postpartum period

Some of the changes in the integumentary system and its associated structures clear spontaneously following delivery; other alterations may regress or fade but do not disappear completely (see previous section for specific skin changes). Hyperpigmentation fades in many women; however, these changes may remain, especially in women with darker skin and hair. In addition melasma may persist for months postpartum in up to 30% of women.⁹³ After delivery, striae gravidarum and spider nevi fade and capillary hemangiomas, varicosities, and skin tags regress. However, these changes may not completely disappear.^61,93,96 Increased body and facial hair usually regresses by 6 months postpartum; thinning or regression of the hairline may not reverse completely.⁷⁷ Alterations in hair growth during pregnancy result in an increased hair loss during the postpartum period in many women.

Hair loss

The scalp contains approximately 100,000 hair follicles. Hair fibers in each follicle independently cycle through three stages: anagen, catagen, and telogen. The anagen or growth stage lasts for 3 to 4 years and is characterized by intense metabolic activity. In this stage, hair grows an average of 0.34 mm/day.⁹³ Catagen is a transitional stage that lasts several weeks. During this stage, metabolic activity and growth slow as the hair bulb is retracted upward into the follicle. Growth of the hair fiber stops during telogen (resting stage). Eventually a new hair bulb begins growing, which ejects the previous hair.⁹³ Normally about 80% of hair follicles are in the anagen stage and 15% to 20% of hair fibers are in the telogen stage, with about 100 to 150 hairs shed per day.⁹⁶

Under the influence of estrogen during pregnancy, the rate of hair growth slows and the anagen stage is prolonged. This results in an increased number of anagen hairs and a decrease in telogen hairs to less than 10% during the second and third trimesters. During the postpartum period, with the decline in estrogens, these anagen hairs enter catagen and then telogen and are shed. Since there are more anagen hairs (and thus eventually telogen hairs) than usual, most postpartum women experience an increased hair loss, beginning 4 to 20 weeks after delivery. During this time, 30% to 35% of the hairs may enter telogen. Generally, complete regrowth occurs by 4 to 6 months in two thirds of women and by 15 months in the remainder, although the hair may be less abundant than before pregnancy.^13,93,96,113 Telogen effluvium is the term used to describe the rapid transition of hair follicles into the telogen stage following delivery, surgery, or severe emotional or physical stress.^93,96,118

Clinical implications for the pregnant woman and her fetus

The physiologic changes in the integumentary system during pregnancy and after delivery are common experiences for many women. These changes seldom significantly alter the function or structure of the integumentary system and are considered by some to be minor nuisances.⁹⁶ However, these changes may have significant psychological and cosmetic implications for the pregnant woman and can contribute to alterations in body image. General interventions include anticipatory counseling, education, and reassurance (see Table 14-1).

Dermatoses associated with pregnancy

In addition to the normal physiologic skin changes associated with pregnancy, there are several integumentary disorders that are unique to pregnancy. Specific dermatoses seen only during pregnancy include pemphigoid gestationis, impetigo herpetiformis, atopic eruptions of pregnancy/prurigo of pregnancy, pruritic urticarial papules and plaques of pregnancy (PUPPP) or polymorphic eruption of pregnancy (PEP), and intrahepatic cholestasis of pregnancy.^61,93,96 Several of these disorders have been associated with increased fetal morbidity and mortality (see Table 14-2). Most of these disorders resolve spontaneously within a few weeks after delivery, but can recur with subsequent pregnancies.⁹³

The etiology of some of these disorders is unclear, although others have a hormonal or immunologic basis. For example, pemphigoid gestationis is an autoimmune disorder with production of anti–human leukocyte antigen (HLA) autoantibody against basal membranes that hold the epidermis and dermis together (see Table 14-2).^20,40,97 There has sometimes been confusion in classifying some of the rarer dermatoses, in that much of the literature regarding these disorders involves reports of small numbers of women, which may represent different variations of the same disorder. Treatment involves use of topical emollients, antipruritics, cold compresses, oatmeal baths (for relief of itching), and topical steroids. In women with moderate to severe eruptions, systemic steroids and antihistamines may be used. Cautions must be used in prescribing these and other dermatologic agents during pregnancy as some, such as retinoic acid, are teratogenic (see Chapter 7) and thus are contraindicated in pregnancy. There are limited data for most other agents on their use in pregnancy. Thus risk-benefit must be carefully evaluated.^17,93

Effects of pregnancy on pre existing skin disorders

The effects of pregnancy on pre existing skin disorders varies from no effect to marked improvement or worsening.^28,93,96,118 With disorders such as psoriasis, eczema, contact dermatitis, and acne vulgaris, this range of effects during pregnancy has been described within the same disease in different women.⁹³ Neurofibromas increase in size during pregnancy and new tumors may appear.⁹³ The effect of pregnancy on malignant melanoma is also variable.^22,93 No significant effect on survival in women with a diagnosis of localized melanoma (stage I or II) during pregnancy was found in an analysis of six case controlled studies.²⁷ Decreased survival or shorter disease-free survival for pregnant women with recurrent melanoma is reported in some studies.^22,27 Effects of pregnancy on other integumentary disorders are reviewed in the literature.^93,96

Summary

The effects of pregnancy on the integumentary system include physiologic changes in the skin and its appendages that are experienced by most pregnant women, skin disorders that are unique to pregnancy, and possible changes in pre existing skin disorders. Nursing management of the pregnant woman in relation to these effects includes preparation for the physiologic changes and their sequelae, and reassurance and support, as well as assessment for the specific dermatoses of pregnancy that are associated with maternal systemic symptoms and, if severe and untreated, with increased fetal mortality and morbidity. Clinical recommendations related to changes in the integumentary system during pregnancy are summarized in Table 14-3.

Development of the integumentary system in the fetus

Anatomic development

The basic structure of the skin develops during the first 60 days of gestation. Around the time of transition from embryo to fetus, the skin undergoes a series of rapid morphologic changes, including keratinization of the epidermal appendages (around 15 weeks) and interfollicular epithelium (around 22 to 24 weeks).¹⁹ By the third trimester, the structure of the skin is similar to that of the adult. However, its barrier properties are still immature, especially in the infant born before term.¹⁹ Further maturation of the skin occurs within the first weeks after birth and during infancy.^9,82,106,114

The skin consists of the epidermis and dermis with an underlying subcutaneous layer (Figure 14-1). The epidermis consists of an outer stratum corneum, stratum granulosum, and the stratum germinativum, which consists of the stratum spinosum, and stratum basale (adjacent to the epidermal-dermal junction). The basal layer contaikns melanocytes (pigment-producing cells) and keratinocytes. Keratinocytes, the major cell of the epidermis, develop from stem cells in the basal layer and migrate outward to cornify the outer layer.³⁵ The stratum corneum is the barrier layer and consists of keratinocytes linked by lipids. Underneath the epidermis lies the dermis, formed from fibrous protein, collagen, and elastin fibers woven together. The dermis contains the nerves and blood vessels that nourish the skin cells and carry sensations from the skin to the brain (see Figure 14-1). Mechanical properties of the dermis include tensile strength, compressibility, resilience, and elasticity.¹⁹ The subcutaneous layer is composed of fatty connective tissue that provides insulation and caloric storage.⁷¹ The epidermis and dermis, along with their vascular and neural networks, develop concurrently.

Epidermis

Development of the epidermis “is characterized by coordinated establishment of increasing numbers of cell layers concomitant with expansion of skin surface area and cellular (keratinocyte) differentiation.”¹⁹ The epidermis develops from undifferentiated ectoderm at 5 to 8 weeks.⁴⁹ It initially consists of a single layer of cuboidal cells that develop from the outer germinal stratum (surface ectoderm) and can be identified during the third week of gestation (Figure 14-2, A). By 30 to 40 days, two layers are seen: the inner basal layer and the outer periderm (see Figure 14-2, B).^35,66 The definitive epidermis develops from the basal layer.

The periderm is a transient embryonic layer that disappears in the second half of gestation.^19,66

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