Occasionally, the muscles of the abdominal walls do not withstand the tension of the expanding pregnancy. As a result, rectus muscles separate in the midline, creating diastasis recti of varying extent. If severe, a considerable portion of the anterior uterine wall is covered by only a layer of skin, attenuated fascia, and peritoneum to form a ventral hernia.
This develops in up to 90 percent of women and is usually more accentuated in those with darker complexion (Ikino, 2015). Of speciic sites, the pigmented skin line in the midline of the anterior abdominal wall-the linea alba-takes on dark brownblack pigmentation to form the linea nigra. Occasionally, irregular brownish patches of varying size appear on the face and neck, giving rise to chloasma or melasma gravidarum-the mask of pregnancy. Pigmentation of the areolae and genital skin may also be accentuated. Mter delivery, these pigmentary changes usually disappear or at least regress considerably. Oral contraceptives may cause similar alterations (Handel, 2014).
he etiology of these pigmentary changes is incompletely understood, however, hormonal and genetic factors play a role. For example, levels of melanocyte-stimulating hormone, a polypeptide similar to corticotropin, are elevated remarkably throughout pregnancy, and estrogen and progesterone also are reported to have melanocyte-stimulating efects .
Angiomas, called vascular spiders, are particularly common on the face, neck, upper chest, and arms. These are minute, red skin papules with radicles branching out from a central lesion. he condition is often designated as nevus, angioma,
TABLE 4-1. Additional Energy Demands During Normal Pregnancya
Rates of Tissue Deposition
Energy Cost of Pregnancy Estimated from Basal Metabolic Rate and Energy Deposition aAssumes an average gestational weight gain of 12 kg.
bEfficiency of food energy utilization for protein and fat deposition estimated as 0.90. Adapted from the World Health Organization, 2004.
or telangiectasis. Palmar eythema is encountered during pregnancy. Both conditions lack clinical significance and disappear in most gravidas shortly after pregnancy. hey are likely the consequence ofhyperestrogenemia. In addition to these discrete lesions, increased cutaneous blood flow in pregnancy serves to dissipate excess heat generated by the augmented metabolism.
hroughout life, the human hair follicle undergoes a pattern of cyclic activity that includes periods of hair growth (anagen phase), apoptosis-driven involution (catagen phase), and a resting period (telogen phase). Based on a study of 116 healthy pregnant women, the anagen phase lengthens during pregnancy and the telogen rate increases postpartum (Gizlenti, 2014). Neither is exaggerated in most gravidas, but excessive hair loss in the puerperium is termed telogen fluvium.
In response to the greater demands of the rapidly growing fetus and placenta, the pregnant woman undergoes metabolic changes that are numerous and intense. By the third trimester, maternal basal metabolic rate rises by 20 percent compared with that of the nonpregnant state (Berggren, 2015). This rate grows by an additional 10 percent in women with a twin gestation (Shinagawa, 2005). Viewed another way, the additional total pregnancy energy demand associated with normal pregnancy approximates kcal (World Health Organization, 2004). This is stratified as 85, 285, and 475 kcal/d during the irst, second, and third trimester, respectively (Table 4-1). Of note, Abeysekera and coworkers (2016) reported that women accrue fat mass during pregnancy despite the increased total energy expenditure and without signiicant change in energy intake. This suggests more eicient energy storage.