Neurologic, muscular, and sensory systems
Maternal physiologic adaptations
During pregnancy the neurologic, muscular, and sensory systems are influenced by the altered hormonal milieu and by alterations in other systems. The effects of these changes on the muscular and sensory systems are well documented. Many of the hormones of pregnancy also have CNS activity, although their specific effects on neurologic function are not as well understood as their effects on other body systems. As a result, there is little known about specific changes in the function of the neurologic system during pregnancy, other than effects on endocrine glands (see Chapter 19). During the intrapartum period, maternal physiologic and psychologic responses are altered by the discomfort and pain of labor. These responses can have a significant impact on fetal homeostasis in addition to having important implications for management of the woman in labor.
Antepartum period
Ocular changes
The eyes of the pregnant woman undergo several alterations during pregnancy that result from physiologic and hormonal adaptations. The pregnant woman develops a mild corneal edema, particularly during the third trimester. The cornea becomes slightly thicker, which (along with the fluid retention) changes its topography and may slightly alter the refractory power of the eye. Corneal hyposensitivity may sometimes also develops during this period, probably because of the increased thickness and fluid retention.172,182,217,238 A few women experience an increase in corneal epithelial pigmentation (known as Krukenberg spindles), possibly secondary to increases in estrogens, progesterone, adrenocorticotropic hormone (ACTH), and melanocyte-stimulating hormone.45,182 The composition of tears changes slightly with an increase in secretion of lysozyme.172 Disruption of lacrimal acinar cells can lead to dry eyes.182
Most studies report that intraocular pressure falls about 10%, especially during the second half of gestation (after 28 weeks), although variations are seen among women in the degree of change.45,54,77,182,196,217 This change is believed to be due to the effects of progesterone, relaxin, and human chorionic gonadotropin combined with an increase in aqueous outflow and decreased episcleral pressure.45,224,238 Similar findings have been reported for women on oral contraceptives. The decrease in intraocular pressure is greater in multiparas than primiparas.196 Changes in intraocular pressure are independent of changes in systemic blood pressure.77 An increase in intraocular pressure has been reported in women with preeclampsia. This increase is not correlated with blood pressure, but may be due to increased extracellular fluid volume and decreased aqueous humor outflow in the preeclamptic woman.77
Ptosis, usually unilateral, occasionally develops for unknown reasons, but may be related to changes in the levator aponeurosis due to hormonal and fluid changes or stress.172,182,238 Ptosis may also occur as a complication of lumbar anesthesia, either as an isolated finding or as part of Horner syndrome. Horner syndrome is characterized by ptosis, miosis, and anhidrosis secondary to interruption of sympathetic innervation.238 Some women experience an increased pigmentation of the face and eyelids known as melasma (see Chapter 14).
During pregnancy there is a progressive decrease in blood flow to the conjunctiva, which is sensitive to estrogen. This change is most marked in women with preeclampsia as a result of spasm and ischemia.11 In these women, changes in the conjunctival vessels may occur earlier than in the retinal vessels. Subconjunctival hemorrhages may occur spontaneously during pregnancy or in labor, with spontaneous resolution.
Otolaryngeal changes
Changes in the ear, nose, and larynx are related to modifications in fluid dynamics and vascular permeability, increased protein synthesis, vasomotor alterations of the autonomic nervous system, and increased vascularity, along with hormonal (especially estrogen) influences.65,135,208,215 As a result of these alterations, the nasal mucosa becomes congested and hyperemic. The pregnant woman experiences nasal stuffiness and obstruction associated with serous rhinorrhea or postnasal discharge. Altered olfactory perception with increased sensation to smell has also been reported.35,129
Pregnancy rhinitis (defined as nasal congestion that lasts 6 or more weeks without signs of infection or allergy) is seen in up to 30% of all pregnant women and in approximately two thirds of those who smoke.65,129,183 These symptoms may appear anytime but usually begin in the second trimester and parallel increasing estrogen levels.65,195,242 The symptoms may interfere with sleep and the sense of smell. The cause is unknown, but placental growth hormone has been implicated as a stimulator of nasal mucosal growth.65 The rhinitis may also be due to increased sensitivity to allergens in women with subclinical allergy.129 Vascular congestion may result in epistaxis from rupture of superficial blood vessels. External nasal alar dilators or nasal washings with a saline solution may provide some relief.65 Systemic antihistamines should be used with caution and only for short periods. Pseudoephedrine should be avoided, especially in the first trimester due to a reported increase in the risk of gastroschisis.215 Prolonged use (over 3 to 5 days) of topical sympathomimetic nasal sprays should be avoided because they can cause rebound congestion.65,135,195,242
The pregnant woman may also complain of ear stuffiness or blocked ears unrelieved by swallowing. This change is believed to result from estrogen-induced changes in mucous membranes of the eustachian tube, edema of the nasopharynx, and alterations in fluid dynamics and pressures of the middle ear.129,135,195,242 Some women may experience a transient, mild hearing loss, and an increased risk of serous effusion. Management is usually supportive. Increased estrogen and progesterone leads to transient vertigo in some women.129,216,242 Tinnitus is more common during pregnancy, possibly due to hyperdynamic circulation, increased peripheral lymphatic fluid, and hormonal changes.129,216 Symptoms resolve with delivery. Ménière’s disease may be exacerbated during pregnancy because of fluid retention.242
Laryngeal changes during pregnancy are hormonally induced and include erythema and edema of the vocal cords accompanied by vascular dilation and small submucosal hemorrhages.139,195,242 The woman may note hoarseness, deepening or cracking of the voice, persistent cough, or other vocal changes. Some women report the quality of their voice improves during the first two trimesters due to better lubrication of the vocal cords.94 Laryngeal changes can complicate administration of endotracheal anesthesia. Similar changes are reported in women premenstrually and with use of progesterone-dominated oral contraceptives.195 Maximal phonation time decreases and vocal fatigue is more prevalent during pregnancy, possibly due to the decreased thoracic cage volume with uterine growth.94 The airway becomes hyperemic with mucosal edema and a decreased diameter of the upper airway, which may increase snoring and sleep disorders.29,75 The edema arises from the increased plasma volume and capillary congestion.29,139
Musculoskeletal changes
Pregnancy is characterized by changes in posture and gait. Relaxin and progesterone affect the cartilage and connective tissue of the sacroiliac joints and the symphysis pubis. This, along with external rotation of the femurs, increases the mobility of these joints and leads to the characteristic “waddle” gait seen in many pregnant women.71,116,165 Widening and increased mobility of the sacroiliac synchondroses and symphysis pubis begins by 10 to 12 weeks.103 The symphysis pubis may widen up to 10 mm.26,116
Musculoskeletal changes during pregnancy may also be due to changes in gait to compensate for the increase in and redistribution of body mass.71 The altered gait in pregnancy may increase the load on the lateral side of the foot and hindfoot, leading to lower limb pain. Ligamentous laxity increases due primarily to the effects of estrogen.26,203 Estrogen and progesterone receptors on fibroblasts within the walls of the blood vessels supplying the anterior cruciate ligaments increase during pregnancy, with decreased collagen synthesis and increased relaxin. Relaxin remodels collagen fibers and reduces their diameters.26 The risk of ligament injury is increased during pregnancy.116 Muscle cramps are more frequent in pregnant women, especially during the second half of pregnancy and at night (see Chapter 17).105,116
Pregnant women often experience back pain and other discomforts (see section on Musculoskeletal Discomforts). Distention of the abdomen with growth of the fetus tilts the pelvis forward, shifting the center of gravity. The woman compensates by developing an increased curvature (lordosis) of the spine that may strain muscles and ligaments of the back. Stretching and decreased tone of the abdominal muscles also contribute to the lordosis. Diastasis of the rectus abdominis muscles in the third trimester may persist after delivery. Breast tenderness, heaviness, tingling, and occasionally pain occur by 6 weeks. These changes are due to estrogens, progesterone, human placental lactogen (hPL), increased blood volume, and venous stasis. Long-term bed rest can lead to muscle atrophy and change gastrocnemius muscle metabolism.20,154 Muscle recovery postpartum can take more than six weeks.20,154
Sleep
Sleep patterns are altered during pregnancy and the postpartum period. Sleep quality and insomnia tend to be most prominent in the first and third trimesters.59,106,123,137,212,218 With advancing gestation total sleep hours progressively decrease.123 Sleep time also decreases prior to labor onset with an increase in night awakenings reported beginning about 5 days prior to labor onset.17 Both hormonal and mechanical factors alter the pregnant woman’s sleep-wake patterns (Figure 15-1).209,212 Sleep is divided into rapid eye movement (REM) and non–rapid eye movement (NREM) or deep sleep, which is subdivided into four stages. Hormonal changes alter sleep during pregnancy. Progesterone has a sedative effect and increases NREM sleep.209,212 Estrogens and cortisol decrease REM, whereas prolactin increases both REM and NREM sleep.61,212 Changes in sleep stages are seen by 11 to 12 weeks.139 In general, pregnant women tend to have less deep and lighter sleep and more awakenings (from less than 5% to 10% by the third trimester).139
During the first trimester, total sleep time increases, as does napping. By the second half of gestation, pregnant women have less overall sleep time and more night awakenings than nonpregnant women do. The pregnant woman has decreased REM sleep in the third trimester, along with increased awakenings and napping, and diminished alertness during the day.59,104,106,137,212 Early-onset REM sleep is reported in pregnant women with depression or mood disorders.139 Alterations in NREM sleep with an increase in stage 1 (sleep latency or transition between wakefulness and sleep) and a decrease in stages 2 and 4 (delta sleep or deep sleep stage) during late pregnancy have also been noted.122,137 The decrease in stage 4 NREM sleep has implications for the pregnant woman’s functioning, because this stage is important for basic biologic processes such as tissue repair and recovery from fatigue.140 In summary, changes to sleep reported during the first trimester include increased total sleep, napping, daytime sleepiness and insomnia, and decreased REM, and stage 3 and stage 4 NREM sleep; changes during the second trimester included increased awakenings with normal total sleep times and decreased REM, stage 3 NREM, and stage 4 NREM sleep; third trimester changes included increased daytime sleepiness, insomnia, nocturnal awakenings, and stage 1 NREM sleep, and decreased REM, stage 3 NREM, and stage 4 NREM sleep.59.106,122,137,212,218,236 During pregnancy, night awakenings are often associated with nocturia, dyspnea, heartburn, uterine activity, nasal congestion, muscle aches, stress, and anxiety and can lead to sleep disturbances and insomnia. The major reasons given by women for sleep alterations include urinary frequency, backache, leg cramps, restless legs, heartburn, and fetal activity.61,104,139,236 Interventions include establishing regular sleep-wake habits and periods, avoiding caffeine, relaxation techniques, massage, heat and support for lower back pain, modifying the sleep environment, and limiting fluids in the evening.212 Sleep medications should be avoided because these drugs alter the physiologic mechanisms of sleep by suppressing REM and NREM stages 3 and 4 and may cross the placenta to the fetus. Sleep loss (i.e., sleeping less than 6 hours per night) in the last 3 to 4 weeks of pregnancy may increase labor length and need for cesarean birth.76,94,138,259
A pregnancy-associated sleep disorder has been described by the American Sleep Disorders Association.9 Individuals with sleep disorder breathing may have an increase in severity during pregnancy due to partial airway obstruction by otolaryngeal changes.29,208,209 Increases are also reported in snoring and possibly obstructive sleep apnea (OSA), although the prevalence of OSA during pregnancy is not well documented.29,75,208,209 The prevalence of snoring during pregnancy is 15% to 30% by the third trimester.139 An increase in hypertension, preeclampsia, gestational diabetes, and fetal growth restriction has been reported in pregnant women who snore.28,29,75,168
Intrapartum period
Pain and discomfort during labor
The woman in labor experiences two types of pain: visceral and somatic. Visceral pain is related to contraction of the uterus and dilation and stretching of the cervix. Uterine pain during the first stage of labor results from ischemia caused by constriction and contraction of the arteries supplying the myometrium. Somatic pain is caused by pressure of the presenting part on the birth canal, vulva, and perineum. Visceral pain is experienced primarily during the first stage of labor; somatic pain is experienced during transition and the second stage.68 Somatic pain is more intense and localized.
The corpus of the uterus is relatively denervated by late pregnancy while the cervix remains densely innervated.240 This suggests that the cervical area maybe the major site of pain in labor.240 Near term numbers of nerve cells and fibers in the sensory area of the spinal column decrease accompanied by increased excitability of mechanosensitive efferents in the cervix.125,181 The pain threshold may be altered in late pregnancy, enhanced by elevated β-endorphins, leading to a proposed “pregnancy-induced hypoanalgesia” (see next section).79,125,181
Pain from uterine contractions and dilation of the cervix during the first stage of labor is transmitted by afferent fibers to the sympathetic chain of the posterior spinal cord at T10 to T12, and L1. In early labor, pain is transmitted primarily to T11 to T12 (Figure 15-2).68,79,206 As activation of peripheral small A-delta (myelinated) and C afferent (unmyelinated) nerve fibers of these nerve terminals (by kinin-like substances released from the uterine and cervical tissues) intensifies, transmission spreads to T10 and L1. Pain during the first stage may be referred; that is, the nerve impulses from the uterus and cervix stimulate spinal cord neurons, innervating both the uterus and the abdominal wall. As a result, the woman experiences pain over the abdominal wall between the umbilicus and symphysis pubis, around the iliac crests to the gluteal area, radiating down the thighs, and in the lumbar and sacral regions.79,231 During transition and the second stage, somatic pain impulses from distention of the birth canal, vulva, and perineum by the presenting part are transmitted by the pudendal nerves through the posterior roots of the parasympathetic chain at S2, S3, and S4.41,79
Peripheral tissue injury and inflammation change the transcription and function of channels and receptors in the peripheral and central nervous systems.102,240 Inflammation (mediated by prostaglandins, cytokines, granulocytes, integrins, and metalloproteases) activates nociceptive nerve fibers, decreasing their threshold and increasing action potentials.102,127 This visceral hypersensitivity is mediated by ion- and acid-sensitive channels, and by prostaglandin E2, N-methyl-d-aspartate (NMDA), and other receptors.102 Stimulation of dorsal root NMDA receptors mediates central hypersensitivity.127
As the A-delta and C nerve fibers enter the dorsal horn of the spinal cord, they synapse and ascend to the brainstem by the spinothalamic tract (see Figure 15-2). The pain impulses entering the brain stimulate a variety of neurons, including cortical neurons and those of the brainstem reticular formation (integrative function), thalamus, hypothalamus, and limbic system.206 The result is a conscious sensation of pain as well as a variety of ventilatory, circulatory, and metabolic responses. Spatial and temporal summation is processed in the cortex.151,206 These responses include increases in ventilation, cardiac output, peripheral resistance, gastric acid secretion, metabolic rate, oxygen consumption, and catecholamine release.
The perception of pain is influenced by physiologic, psychologic, and cultural factors. Pain can lead to anxiety and influence maternal physiologic responses and the course of labor. For example, physical manifestations of anxiety may include muscular tension, hyperventilation, increased sympathetic activity, and norepinephrine release, which can lead to increased cardiac output, blood pressure, metabolic rate, and oxygen consumption and impaired uterine contractility (Figure 15-3).18,119,205 Anxiety can also increase fear and tension, reducing pain tolerance, which decreases uterine contractility.18,119,151 Relaxation techniques such as progressive muscle relaxation, touch, breathing, imagery, and autosuggestion help reduce anxiety and prevent or stop this cycle.119
Descending spinal tracts in the dorsal horn modulate nociception via input from the cortex and limbic system with release of endogenous opioids such as β-endorphins and enkephalins (see next section).205 These modulating factors are produced by the placenta as well as the mother and may include an opioid-enhancing factor.205 Other modulating factors include analgesia induced by mechanical stimulation of the hypogastric (uterine mechanical stimulation) and pelvic (vaginal distention) nerves.206 Exogenous modification of labor pain includes both pharmacologic (opioids, sedatives, analgesics, anesthetics) interventions and nonpharmacologic cognitive, behavioral, and sensory techniques.70,156 These techniques include relaxation, cognitive and behavioral childbirth preparation, hypnosis, acupuncture, movement, positioning, vocalizations, touch, massage, music, biofeedback, transcutaneous electrical nerve stimulation (TENS), and hydrotherapy (Table 15-1).13,15,18,41,62,70,113,119,206,225,227,229
Table 15-1
Proposed Mechanisms of Labor Pain Reduction with Various Nonpharmacologic Measures
| MECHANISMS | ACUPUNCTURE/ACUPRESSURE | AROMATHERAPY | BREATHING/FOCUS | CHILDBIRTH EDUCATION | COLD | EMOTIONAL SUPPORT | HEAT | HYDROTHERAPY | HYPNOSIS | INTRADERMAL WATER BLOCK | MASSAGE/TOUCH | MOVEMENT AND POSITIONING | MUSIC/AUDIOANALGESIA | RELAXATION | TENS |
| Counterirritation analgesia (brief intense stimulation of trigger points) | X | X | X | ||||||||||||
| Increases endorphins | X | X | X | X | |||||||||||
| Provides stimuli from peripheral sensory receptors to inhibit pain awareness | X | X | X | X | X | X | X | ||||||||
| Increases joint mobility | X | X | X | ||||||||||||
| Alters pressures within pelvis and on soft tissues | X | X | X | ||||||||||||
| Improves energy flow along meridians crucial to labor progress and comfort | X | X | |||||||||||||
| Decreases muscle tension | X | X | X | X | X | X | X | ||||||||
| Alters nerve conduction velocity (slows pain transmission to CNS) | X | ||||||||||||||
| Decreases anxiety/fear, provides reassurance | X | X | X | X | X | X | X | X | X | ||||||
| Increases woman’s sense of control, reducing pain perception | X | X | X | X | X | X | X | X | |||||||
| Distraction of attention from pain | X | X | X | X | X | X | X | X | X | X | X | ||||
| Enhances or changes mood, reducing pain perception | X | X | X | X | X | X | |||||||||
| Cues rhythmic activity and rituals | X | X | X | X | X |
CNS, Central nervous system; TENS, transcutaneous electrical nerve stimulation.
From Simkin, P. & Bolding, A. (2004). Update on nonpharmacologic approaches to relieve labor pain and prevent suffering. J Midwifery Womens Health, 49, 491.
“The theory proposes that a neural mechanism in the dorsal horns of the spinal cord acts like a gate which can increase or decrease the flow of nerve impulses from peripheral fibers to the central nervous system. Somatic input is therefore subjected to the modulating influence of the gate before it evokes pain perception and response. The degree to which the gate increases or decreases sensory transmission is determined by the relative activity in large-diameter (A-beta) and small diameter (A-delta and C) fibers and by descending influences from the brain. When the amount of information that passes through the gate exceeds a critical level, it activates the neural areas responsible for pain experience and response.”163, p. 222
Techniques to close the gate (inhibit) include stimulation of large nerve fibers to block impulses from the smaller pain fibers. This provides a basis for use of massage and effleurage during labor. With continued use of these techniques, the large nerve fibers become habituated and stimuli from smaller fibers are no longer blocked. Thus, as labor progresses, the woman needs to stimulate other fibers (using techniques such as heat, pressure with change of position, and massage of other areas). Because descending fibers may also inhibit transmission to the brain, concentration techniques may also be useful.41,119,157
The neuromatrix theory of pain expands on the gate control theory and emphasizes that pain is a multi-dimensional, whole body-mind-spirit experience that may underlie the basis for the efficacy of nonpharmacologic pain interventions during labor.114,162,243
“The neuromatrix theory incorporates many of the same elements of the gate control theory. Both theories view the brain as the ultimate arbitrator of the multiple dimensions of pain. However, the gate control theory emphasizes the opening or closing of a gate at the level of the spinal cord as the preeminent mechanism controlling the ultimate perception of pain. The neuromatrix theory of pain recognizes the simultaneous convergence of a panoply of influences, including one’s past experiences, cultural factors, emotional state, cognitive input, stress regulation, and immune systems, as well as immediate sensory input . . . The multiple influences that create pain perception are generated from 3 parallel processing networks: sensory-discriminative (somatosensory components), affective-motivational (limbic system components), and evaluative-cognitive (thalamocortical components). Additional contributions of the autonomic nervous system, the stress response system, and immune system modulation are also recognized in this model.”243,p.483
β-endorphins
Pain during the intrapartum period may be modulated by endogenous opiate peptides such as β-endorphins (B-EPs) and enkephalins. These substances are prohormones derived from precursor proteins such as prepro-opiomelanocortin (POMC) for B-EP and preproenkephalin for enkephalin.78 POMC, found in the anterior pituitary gland, also contains the sequence for ACTH (see Chapter 19) and melanocyte-stimulating hormone. B-EP is also produced by the placenta. Endogenous opioids alter the release of neurotransmitters from afferent nerves and interfere with efferent pathways from the spinal cord to the brain. Thus, within the spinal cord, pain signals may be blocked at the level of the dorsal horns and never be transmitted to the brain. B-EP and other endogenous opioids, in addition to their analgesic role, may also alter mood during pregnancy and have a role in regulation of secretion of pituitary hormones.78 For example, B-EP appears to modulate release of luteinizing hormone, prolactin, growth hormone, and follicle-stimulating hormone by the anterior pituitary and arginine vasopressin from the posterior pituitary gland.78
Maternal plasma B-EP levels increase during pregnancy, especially from 28 weeks on, and are significantly elevated during late pregnancy and labor.46,78 Increased levels may be related to the increase in corticotropin-releasing hormone near term (see Chapters 4 and 19).46 Maximum levels of B-EP are found during parturition and decrease postpartum.260 Levels correlate with uterine muscle contraction and cervical effacement. B-EP release may be stimulated by stress as an adaptive response. Endorphins may increase the pain threshold, are associated with feelings of euphoria and analgesia, and may enable the woman to tolerate the pain of labor and delivery.
The increased levels of B-EP during labor may contribute to the decreased doses of anesthetic drugs generally required in pregnant women compared with nonpregnant women.46,79 Women with low B-EP levels at term may have a greater need for pain medication during labor.46,79 The variable decrease in doses of local anesthetics for epidural and spinal blocks is also caused by vascular congestion within the spinal canal and progesterone as well as the altered neuronal sensitivity. Increased progesterone levels also contribute to the decreased doses of inhalation anesthetics needed for pregnant women through their effect on the respiratory system.
Postpartum period
B-EP levels decrease by 24 hours after birth. Levels are higher after vaginal versus cesarean birth.260 Levels of B-EP are twice as high in colostrum as in maternal plasma and may assist the newborn in the transition to extrauterine life and mediate the stressful events of labor and delivery.260
During the postpartum period the ocular and otolaryngeal changes resolve as the physiologic and hormonal adaptations of pregnancy are reversed. Sensitivity of the cornea returns to the usual parameters by 6 to 8 weeks postpartum.172 Intraocular pressure returns to prepregnancy levels by 2 to 3 months postpartum.224 Both ptosis and subconjunctival hemorrhages disappear spontaneously.172 Nasal congestion, ear stuffiness, tinnitus, and laryngeal changes and related discomforts usually disappear within a few days after delivery.65,94,129,215,216 Headaches, generally bilateral and frontal, are a common discomfort in the first week after delivery. Postpartum headaches tend to begin around the time of postpartum weight loss and have been attributed to alterations in fluid and electrolyte balance.
Sleep during the postpartum period
Sleep is altered during the immediate postpartum period. Most of these changes normalize after the first weeks postpartum, but primiparas may experience altered sleep for up to 3 months.61,137 Stage 1 NREM sleep is longer immediately after birth than before birth. Stage 4 NREM sleep is also longer immediately after birth than before birth, with a gradual change to prepregnancy levels by about 2 weeks. REM sleep is decreased and awake time increased on the first postpartum night, with a reversal of these findings by 3 days.112,122 These changes are probably related to the initial euphoria and discomfort after childbirth, followed by fatigue and restoration. Postpartum women have less overall sleep time and more night awakenings than nonpregnant women do. These night awakenings are often associated with urination, discomfort, activity by roommates or nursing staff, and infant feeding. Opportunities for restorative sleep after delivery and during the first postpartum night are often impeded by the environment and interruptions for nursing care activities.112,140 Disturbances in maternal sleep lead to fatigue and a perceived lack of sleep effectivensss.207
The main reasons for night wakening postpartum are newborn sleep and feeding patterns.112 Maternal night wakefulness decreases significantly from weeks 3 to 12.178 This decrease is related to development of the infant’s sleep-wake rhythm. Women who breastfeed have more deep sleep and overall sleep, possibly related to prolactin secretion, less arousal due to closer infant proximity, and infant sleep-wake patterns.24,139,247
Sleep medications alter sleep physiology and suppress REM sleep and NREM stages 3 and 4 and thus should be avoided. OSA and sleep disorder breathing generally resolve postpartum as the changes in the airway and larynx resolve.29,209
Postpartum discomfort
During the first few days to weeks of the postpartum period, the woman may experience considerable discomfort. The discomfort and pain can arise from a variety of sources, including an episiotomy, lacerations, perineal trauma, incisions, uterine contractions after delivery (afterpains), hemorrhoids, breast engorgement, and nipple tenderness. Breast engorgement initially occurs in both the lactating and nonlactating woman because of stasis and distention of the vascular and lymphatic circulations. In the breastfeeding woman, secondary engorgement occurs because of distention of the breast with milk as lactation is established. Alterations in comfort not only cause physical and emotional stress but can also interfere with the ability of the woman to interact with and care for her infant. Back pain generally disappears within a few weeks or months after delivery, although 8% to 10% of women continue to report pain 1 to 2 years later.90,247
Clinical implications for the pregnant woman and her fetus
Ocular adaptations
Although ocular alterations during pregnancy generally do not have major clinical significance, they can result in minor discomforts, particularly for women who wear contact lenses. Some women may be unable to tolerate their lenses and may occasionally develop corneal edema. The basis for this intolerance is believed to be retention of water by the cornea, changes in the composition of tears, and alterations in corneal topography.182,224 Changes in tear composition can make the contact lenses feel greasy shortly after insertion and cause blurring of vision.172,182 Pregnancy may also alter healing following photorefractive keratectomy. Myopic regression and corneal haziness are reported in about 10% of postpartum women.222 Alterations in refractory power along with occasional transient insufficiency of accommodation can cause difficulty in reading and in near vision or blurred vision in someone who is farsighted.172,217,238 These alterations resolve in the postpartum period. New prescriptions for glasses or contact lenses should be delayed until several weeks after delivery.
Women with specific disorders such as preeclampsia and diabetes mellitus may have ocular complications associated with their disease process. Preeclampsia is associated with vasospasm of the conjunctival vessels and narrowing of the retinal arterioles. The latter may progress to severe arteriolar spasm or multiple retinal hemorrhages. Most of these changes reverse within 3 weeks postpartum.224,238 In severe disease retinal detachment may occur.238 Mild to moderate visual disturbances are most common; severe or complete loss of vision is rare.238 However, up to 15% of women with severe preeclampsia develop cortical blindness that is almost always transient, lasting 4 hours to 8 days.224 The changes that occur with preeclampsia may be related to vascular changes, endothelial damage, coexisting systemic vascular disease, altered cerebral autoregulation, and hypoperfusion with ischemia or hyperperfusion with edema.224
Development and progression of diabetic retinopathy in pregnant women are more closely correlated with the duration of the disorder, severity of the diabetes, coexisting hypertension or preeclampsia, and degree of glycemic control.182,217,224 Pregnant diabetic women (particularly those with established proliferative retinopathy) often demonstrate deterioration related to the metabolic and hormonal changes of pregnancy. Some women without diabetic retinopathy at the onset of pregnancy may develop mild nonproliferative diabetic retinopathy (NPDR) during pregnancy and those with NPDR may have progression.217,224 Although reversal of these pregnancy-induced changes usually occurs over the first 6 to 12 months postpartum, some women, especially those with preexisting retinopathy, do not experience complete return to their prepregnant status.54,217,224,238 Careful baseline assessment and surveillance during pregnancy are essential. Women with gestational diabetes are not at increased risk for retinopathy during pregnancy.54,217
Because intraocular pressure falls during pregnancy, the pregnant woman with glaucoma may experience an improvement with a decreased need for medications.54,182,238 This has an additional advantage of reducing fetal exposure to these agents, which should be used with caution and carefully monitored.217 Many ocular inflammatory disorders improve during pregnancy, possibly because of increased cortisol and other glucocorticosteroids, with exacerbation postpartum.
Any symptoms of eye infections in the pregnant woman must be assessed, because some sexually transmitted organisms such as herpes simplex virus and chlamydia may cause concurrent ocular infections. The presence of these organisms can have adverse consequences for the neonate if the mother also has a genital infection. For example, genital chlamydia can cause conjunctivitis and pneumonia in the newborn, and genital herpes simplex virus can cause disseminated or localized neonatal infection. Treatment of maternal ocular disorders during pregnancy should be done cautiously and with attention paid to the possible effects of the medication on the fetus. Even topical eye ointments must be used with caution because they can be absorbed systemically and cross the placenta to the fetus.238 If these agents must be used, nasolacrimal occlusion after instillation may reduce systemic absorption.224
Musculoskeletal discomforts
The pregnant woman may experience discomfort or pain associated with breast changes or stretching of the round ligament with growth of the uterus, pressure of uterine nerve roots, or pressure of the presenting part on the perineum. The latter type of pain is most prominent close to the onset of labor and is aggravated by vascular engorgement of these tissues. Increased joint mobility can result in muscle and ligament strain and discomfort. Pregnant women also have an increased risk of falls.103,159,193 Falls are reported in 27% of pregnant women and are the leading cause of emergency department visits during pregnancy.158,159 The increased risk of falls is related to weight gain, shift in the center of gravity, edema, deceased abdominal muscle strength, changes in mechanical load, ligament laxity, and changes in joint kinetics.158,159 Regular exercise may be useful in reducing the risk of falls.159
Hip and knee joint pain may occur due to ligamentous laxity, joint strain, and weight gain.26,203 A 20% weight gain increases the force on weight-bearing joints by 50% to 100% during pregnancy.203 Knee pain is due to patellofemoral dysfunction from ligamentous laxity, increased femoral torsion, and increased pelvic width.203 Preexisting knee pain may increase or pain may occur for the first time. These changes are usually benign and reverse postpartum.203 Pubic pain results from inflammation of the symphysis pubis and usually responds to rest and ice.203
Many pregnant women experience low back pain (including lumbar pain and pelvic girdle pain) during pregnancy due to a combination of hormonal and mechanical factors including exaggeration of the lumbar lordotic curve due to shifting of the center of gravity, weight gain, and relaxation of ligaments, or from muscle spasm due to pressure on nerve roots.26,95,247 The sacroiliac ligaments, which usually resist femoral rotation, are less likely to do so during pregnancy. This along with the lumbar lordosis “shifts the center of gravity anteriorly, causing a strain on the lower back and sacroiliac joint. As the strong sacroiliac ligaments become increasingly lax during pregnancy, this allows an increase in the forward shift of the uterus, thereby placing more strain on the pelvic floor and back.”203
Backache occurs in about 45% to 50% of women, most commonly after 18 weeks of pregnancy, although high backache earlier may result from breast alterations.57,90,95,103,116,165,247,254 Approximately 10% of these women experience severe back pain, peaking in intensity during the evening and night, and localized to the lower back or sacroiliac region.
An increased frequency of backache is reported in multiparas, in individuals with a history of back pain before pregnancy or with a previous pregnancy, and with increasing maternal age.103,116,203,254 Backache has not been associated with weight gain in pregnancy, height, or infant birth weight.26,103,116,203,247 Women tend to experience less pain if they are physically fit before pregnancy, exercise during pregnancy, and have had education on postural adjustments (e.g., upright posture, tucking the pelvis, rotating shoulders) to reduce back pain.247 Other recommendations include avoiding anything that increases the lordosis (e.g., high-heeled shoes), application of local heat, exercises to increase lower abdominal and back muscle tone beginning early in pregnancy, abdominal pillows, backrubs, use of a firm mattress, bed board, or back support, pelvic tilt exercise, aerobic exercise such as swimming, and conditioning before subsequent pregnancies.57,116,188,247 Acupuncture has also been found to provide relief.131,228 Backache, round ligament pain, or other discomfort should be assessed to distinguish “normal” discomfort from other processes such as preterm labor.
Exacerbation of intervertebral disk disorders is seen during pregnancy and the immediate postpartum period, probably because of postural changes and an increase in mechanical stress.11,26,230 The most frequently affected areas are the fifth lumbar and first sacral nerve roots. Management usually involves bed rest. Spondylolisthesis (slipping of one lumbar vertebra forward onto the vertebra below) especially at L4 to L5 or at L5 to S1 is aggravated.203 True herniation of the disk is rare.95,203,230
