Chapter 1: Preterm Labour
Preterm labour is a syndrome causing approximately 30% of all preterm births. Preterm labour is defined as the occurrence of regular uterine contractions (four or more in 20 minutes or eight or more in 1 hour) and cervical changes (effacement equal to or greater than 80% and dilatation equal to or greater than 1 cm) in women with intact fetal membranes and gestational age less than 37 weeks. However, a gestational age less than 36 weeks is a more commonly accepted threshold of prematurity, and rarely obstetricians make efforts to delay delivery in women in preterm labour once they reach 36 weeks (Spong CY, 2013).
Preterm labour is one of the syndromes characterized by the premature activation of the final pathway of parturition. Preterm labour has multiple causes and the most clearly identified are chorioamniotic infection, abnormal placentation, fetal and maternal stress, and bleeding in the decidual–chorionic interface. Most of these causes can not be modified or abolished by medical intervention and consequently the result of prevention and treatment efforts is disappointing. However, the practitioner should not adopt a nihilistic attitude and efforts should always be made to uncover the underlying reason behind the clinical picture. Even if it is not possible to stop preterm labour, knowledge of the cause of the problem is useful to guide our approach toward important interventions such as tocolysis, antibiotics, and the use of steroids (Berbel et al., 2010).
DIAGNOSIS
• Uterine Contractions:
The main symptom of preterm labour is uterine contractions. They should occur regularly, four or more in 20 minutes or eight or more in 1 hour, and each should last more than 40 seconds. The perception of the frequency, intensity, and duration of contractions by different health care providers is frequently inaccurate and the best objective way to determine the frequency and duration of the contractions is by external monitoring with a tocodynamometer (Frye et al., 2009).
• Digital Pelvic Examination:
The main sign of labour, term or preterm, is the presence of cervical changes. Therefore, when a woman comes to the hospital or the obstetrician’s office complaining of regular uterine contractions, the first thing to do is a digital examination of the cervix. During this examination the obstetrician should assess the position, length, consistency, and dilatation of the cervix, as well as the development of the lower uterine segment. The two more important variables to assess clinically are the length (effacement) and the dilatation of the cervix. Adequate assessment of the cervical effacement is very important and, unfortunately, there is no clear agreement or guidelines about how to effect this measurement. In USA most obstetricians and midwifes express effacement as a percentage and there is universal agreement that the cervix is 100% effaced when it is paper-thin. The problem is with the estimation of intermediate degrees of effacement, because there is no agreement about what is the length of the uneffaced cervix. It is known by ultrasonography that the length of the cervix at term is between 3 and 4 cm. However, the estimation of cervical length for pregnancy at term among practicing obstetricians in a large medical center had a range from 1 to 4 cm with a mean estimate of 2.47 cm (Holcomb and Smeltzer, 1991).
Therefore 50% effacement means a cervical length of 0.5 cm for some and 2.0 cm for others. Furthermore, there is no agreement or guidelines about how to measure the cervical length. Some place one finger inside of the cervix and estimate the length from the external to the internal os. This measurement is imprecise because sometimes it is difficult to recognize the internal os and is impossible to obtain if the cervix is closed. Others estimate cervical length from the distance between the posterior fornix and the external cervical os, a measurement that is also imprecise because in many cases it does not include the supravaginal portio of the cervix. Despite these limitations a consistent measurement of the cervical length (effacement) facilitates communication between clinicians (Aizenman et al., 1990).
In patients with closed or minimally opened cervix, we measure effacement as the length between the posterior fornix and the external cervical os. If the cervix is longer than 1 cm, the length is expressed in centimeters. If it is shorter than 1 cm, length is expressed as effacement (0.75 cm = 25% effacement, 0.50 cm = 50% effacement,0.25 cm = 75% effacement, paper-thin = 100% effacement). If the cervix is dilated enough to admit one finger, the length of the cervix is assessed by estimating the distance from the tip of the examining finger placed in the internal os to the part of the finger that is at the level of the external os. When examined between 20 and 34 weeks of gestation, the large majority of nulliparous patients have cervices pointing posteriorly, closed, at least 2 cm long, and harder in consistency than any other vaginal or uterine tissues. In multiparous women, the cervix may have varying degrees of dilatation, which may be greater in the external than in the internal cervical os (Mathew and MacDorman, 2006).
An important part of the digital examination of the women in preterm labour is the assessment of the lower uterine segment. All pregnant women regardless of their parity or gestational age stretch or develop their lower uterine segment before parturition. When the lower uterine segment is not developed, it is possible to introduce easily the fingers into the vaginal fornices. In contrast, when the lower uterine segment is developed, the examiner finds that the upper third of the vagina is filled with the thinned lower uterine segment. In many patients, development of the lower uterine segment occurs simultaneously with engagement of the presenting part. The finding of a soft, short cervix and a developed lower uterine segment indicates that the cervix is preparing for labour, and investigation about the factors causing the cervical changes is mandatory. When the digital examination reveals that the cervix is more than 80% effaced and dilated 1 cm or more, the diagnosis of preterm labour is clear. However, the degree of cervical dilatation varies, and it is possible to distinguish two groups of women in preterm labour: those with cervices dilated 3 or more cm are in advanced preterm labour and those with a cervical dilatation greater than 1 but less than 3 cm are in early preterm labour. Most women with advanced preterm labour are destined to have a preterm birth. This is not the case for women in early preterm labour and, as we will see later, further refinement in the determination of the risk of preterm delivery in this particular group of patients can be achieved with the use of the fetal fibronectin (FFN) test (Simhan and Caritis, 2007).
The initial digital examination will reveal a large number of women coming to the hospital or to the doctor’s office with frequent uterine contractions that do not show cervical changes consistent with the definition of preterm labour. In these cases the next step is to measure the cervical length with ultrasound. If the ultrasound examination shows a cervical length less than 2.5 cm, the woman is in threatened preterm labour and at high risk for preterm delivery. If the cervical length is 2.5 cm or more, the subject is in spurious or false labour and the risk of preterm delivery is similar to that in the overall obstetrical population (Goldenberg et al., 2008).
In summary, in women who present with frequent, regular uterine contractions the initial digital examination will permit to determine if the woman is in advanced preterm labour (cervix effaced 80% or more and cervix dilated 3 cm or more) or in early preterm labour (cervix effaced 80% or more and dilated 1 or more but less than 3 cm). If the cervix is dilated less than 1 cm or is not effaced, endovaginal ultrasound will permit to identify a third group of women in threatened preterm labour (cervical length less than 2.5 cm).
Advanced Preterm Labour
If the cervix is effaced 80% or more and the cervical dilatation is 3 cm or more, the woman is in advanced preterm labour. Under these circumstances assessment of the cervical length by ultrasound and determination of FFN in the cervicovaginal secretions are unnecessary.
The risk of preterm delivery is high and management will not be changed by performing these tests.
The possibilities of obtaining a significant prolongation of pregnancy for patients admitted to the hospital in advanced preterm labour are limited. Also, for a majority of these patients prolongation of pregnancy offers no fetal advantages because, in these cases, preterm labour is a protective mechanism for fetuses threatened by problems such as infection or placental insufficiency. Because of these reasons, the first step in the management of advanced preterm labour is to determine which patients need to be delivered and which patients may benefit from delaying delivery in order to accrue the benefits of steroid administration (Smith et al., 2003).
Signs and Symptoms
Symptoms of imminent spontaneous preterm birth, are signs of premature labour; one sign is four or more uterine contractions in one hour. In contrast to false labour, true labour is accompanied by cervical dilatation and effacement. Also, vaginal bleeding in the third trimester, heavy pressure in the pelvis, or abdominal or back pain could be indicators that a preterm birth is about to occur. A watery discharge from the vagina may indicate premature rupture of the membranes that surround the baby. While the rupture of the membranes may not be followed by labour, usually delivery is indicated as infection (chorioamnionitis) is a serious threat to both fetus and mother. In some cases the cervix dilates prematurely without pain or perceived contractions, so that the mother may not have warning signs until very late in the birthing process (Goldenberg et al., 2008).
Mortality and Morbidity
The shorter the term of pregnancy, the greater the risks of mortality and morbidity for the baby primarily due to the related prematurity. Preterm-premature babies (“preemies” or “premmies”) have an increased risk of death in the first year of life (infant mortality), with most of that occurring in the first month of life (neonatal mortality). Worldwide, prematurity accounts for 10% of neonatal mortality, or around 500,000 deaths per year. In the U.S. where many infections and other causes of neonatal death have been markedly reduced, prematurity is the leading cause of neonatal mortality at 25%. Prematurely born infants are also at greater risk for having subsequent serious chronic health problems (Mathew and MacDorman, 2006).
As NICU care has improved over the last 40 years, viability has reduced to approximately 24 weeks (Kaempf et al., 2006). Although rare survivors have been documented as early as 21 weeks (Steer, 2005). This date is controversial, as gestation in the case reported was measured from the known date of conception (by IVF) rather than, as usual, the date of the mother’s last menstrual period, making gestation appear two weeks less than if calculated by the conventional method in this case (James, 2007).
Specific Risks for the Preterm Neonate
• Neurological problems include apnea of prematurity, hypoxic-ischemic encephalopathy (HIE), retinopathy of prematurity (ROP), developmental disability, transient hyperammonemia of the newborn, cerebral palsy and intraventricular hemorrhage, the latter affecting 25 percent of babies born preterm, usually before 32 weeks of pregnancy. Mild brain bleeds usually leave no or few lasting complications, but severe bleeds often result in brain damage or even death. Neurodevelopmental problems have been linked to lack of maternal thyroid hormones, at a time when their own thyroid is unable to meet postnatal needs (Berbel et al., 2010).
Children born preterm are more likely to have white matter brain abnormalities early on causing higher risks of cognitive dysfunction (Aizenam et al., 1990) White matter connectivity between the frontal and posterior brain regions are critical in learning to identify patterns in language. Preterm children are at a greater risk for having poor connectivity between these areas leading to learning disabilities (Frye et al., 2009).
Cardiovascular complications may arise from:
Respiratory problems are common; specifically the respiratory distress syndrome (RDS) (previously called hyaline membrane disease). Another problem can be chronic lung disease (previously called bronchopulmonary dysplasia or BPD).
Gastrointestinal and metabolic issues can arise from:
Hypoglycemia, feeding difficulties, rickets of prematurity, hypocalcemia, inguinal hernia, and necrotizing enterocolitis (NEC).
Hematologic complications include:
Anemia of prematurity, thrombocytopenia, and hyperbilirubinemia (jaundice) that can lead to kernicterus.
Infection, including:
Sepsis, pneumonia, and urinary tract infection.
(Mathew and MacDorman, 2006).
Causes
As the cause of labour still remains elusive, the exact cause of preterm birth is also unsolved. In fact, the cause of 50% of preterm births is never determined. Labour is a complex process involving many factors. Four different pathways have been identified that can result in preterm birth and have considerable evidence: precocious fetal endocrine activation, uterine overdistension, decidual bleeding, and intrauterine inflammation/infection. Activation of one or more of these pathways may happen gradually over weeks, even months (Simhan and Caritis, 2007).
From a practical point a number of factors have been identified that are associated with preterm birth, however, an association does not establish causality.
Maternal background
A number of factors have been identified that are linked to a higher risk of a preterm birth: age at the upper and lower end of the reproductive years, being more than 35 (Martius et al., 1995) or less than 18 years of age (Goldenberg et al., 2008). Maternal height and weight can also play a role. Further, in the US and the UK, black women have preterm birth rates of 15–18%, more than double that of the white population, This discrepancy is not seen in comparison to Asian or Hispanic immigrants and remains unexplained. (Goldenberg et al., 2008).
Pregnancy interval makes a difference as women with a 6 months span or less between pregnancies have a two-fold increase in preterm birth (Smith et al., 2003). Studies on type of work and physical activity have given conflicting results, but it is opined that stressful conditions, hard labour, and long hours are probably linked to preterm birth (Goldenberg et al., 2008) Women who have undergone previous surgically induced abortions have been shown to have a higher risk of preterm birth (less than 37 weeks), as well as extreme preterm birth (less than 28 weeks) (Moreau et al., 2005). The preterm birth link has not been shown in women who terminated their pregnancies medically with pills such as RU-486 (Virk et al., 2007). Adequate maternal nutrition is important. Women with a low BMI are at increased risk for preterm birth, further; women with poor nutritional status may also be deficient in vitamins and minerals. Adequate nutrition is critical for fetal development and a diet low in saturated fat and cholesterol may help reduce the risk of a preterm delivery (Hendler et al., 2005). Obesity does not directly lead to preterm birth; however, it is associated with diabetes and hypertension which are risk factors by themselves (Goldenberg et al., 2008). Women with a previous preterm birth are at higher risk for a recurrence at a rate of 15–50% depending on number of previous events and their timing. To some degree those individuals may have underlying conditions (i.e. uterine malformation, hypertension, diabetes) that persist (Mercer et al., 1999).
Genetic make-up is a factor in the causality of preterm birth. An intra- and transgenerational increase in the risk of preterm delivery has been demonstrated. No single gene has been identified, and it appears with the complexity of the labour initiation, that numerous polymorphic genetic interactions are possible (Bhattacharya et al., 2010).
Factors during Pregnancy
Multiple pregnancies (twins, triplets, etc.) are a significant factor in preterm birth. Triplets and more are even more endangered. The use of fertility medication that stimulates the ovary to release multiple eggs and of IVF with embryo transfer of multiple embryos has been implicated as an important factor in preterm birth. Maternal medical conditions increase the risk of preterm birth, and often labour has to be induced for medical reasons; such conditions include high blood pressure, pre-eclampsia, maternal diabetes, asthma, thyroid disease, and heart disease (Bánhidy et al., 2007).
In women with uterine malformations the capacity of the uterus to hold the growing pregnancy may be limited and preterm labour ensues (Acien, 1993).Some women have a weak or short cervix (the strongest predictor of premature birth) (Fonseca et al., 2007). The cervix may also have been compromised by previous cervical conization or loop excision (Goldenberg et al., 1998).
Women with vaginal bleeding during pregnancy are at higher risk for preterm birth. While bleeding in the third trimester may be a sign of placenta previa or placental abruption – conditions that occur frequently preterm – even earlier bleeding that is not caused by these two conditions is linked to a higher preterm birth rate (Krupa et al., 2006).
Women with abnormal amounts of amniotic fluid, too much (polyhydramnios) or too little (oligohydramnios) are also at risk (Goldenberg et al., 2008).
The mental status of the women is of significance. Anxiety (Dole et al., 2003) and depression have been linked to preterm birth (Goldenberg et al., 2008). Finally, the use of tobacco, cocaine, and excessive alcohol during pregnancy also increases the chance of preterm delivery. Tobacco is the most commonly abused drug during pregnancy and also contributes significantly to low birth weight delivery (Parazzini et al., 2003).
Babies with birth defects are at higher risk of being born preterm (Dola et al., 2007). Presence of anti-thyroid antibodies is associated with an increased risk preterm birth (Van Den Boogaard et al., 2011).
Infection
Infections play a major role in the genesis of preterm birth and may account for 25 – 40% of events (Goldenberg et al., 2000). Endotoxins released by microorganisms and cytokines stimulate deciduas responses including the release of prostaglandins which may stimulate uterine contractions. Further the decidual response may include release of matrix-degrading enzymes that weaken fetal membranes leading to premature rupture (Goldenberg et al., 2000).
Micro-organisms may reach the decidua in a number of ways, ascending, hematogeneous, iatrogenic by a procedure, or retrograde through the fallopian tubes. From the deciduas they may reach the space between the amnion and chorion, the amniotic fluid, and finally the fetus (Hillier et al., 1995). Bacterial vaginosis has been linked to preterm birth raising the risk by a factor of 1.5 – 3, It is opined that bacterial vaginosis before or during pregnancy may affect the decidual inflammatory response that leads to preterm birth (Goldenberg et al., 2008).
A number of maternal bacterial infections are associated with preterm birth including pyelonephritis, asymptomatic bacteriuria, pneumonia, appendicitis and periodontal disease have been shown repeatedly to be linked to preterm birth (Jeffcoat et al., 2001). In contrast, viral infections, unless accompanied by a significant febrile response, are considered not to be a major factor in relation to preterm birth (Goldenberg et al., 2008).
Diagnosis
These new tests are used to identify women at risk for preterm birth.
1-Fetal Fibronectin
Fetal fibronectin has become the most important biomarker—the presence of this glycoprotein in the cervical or vaginal secretions indicates that the border between the chorion and deciduas has been disrupted, A positive test indicates an increased risk of preterm birth, and a negative test has a high predictive value (Goldenberg et al., 2008). It has been shown that only 1% of women in questionable cases of preterm labour delivered within the next week when the test was negative (Lu et al., 2001).
2-Ultrasonography of the cervix
Obstetric ultrasound has become useful in the assessment of the cervix in women at risk for premature delivery. At 24 weeks gestation a cervix length of less than 25 mm defines a risk group for preterm birth. Further, the shorter the cervix the greater the risk (Iams et al., 1996). It also has been helpful to use ultrasonography in women with preterm contractions, as those whose cervix length exceeds 30 mm are unlikely to deliver within the next week (Leitich et al., 1999).
Prevention
Primary interventions that are directed at all women, and secondary intervention that reduce existing risks are looked upon as measures that need to be developed and implemented to prevent the health problems of premature infants and children (Iams et al., 2008).
Preconceptional
Reduce repeated uterine instrumentation (i.e. repeated surgical abortions) (Ancel et al., 2004) and to avoid risky choices in infertility treatments.
Preterm birth is not related to type of employment, but to prolonged work (over 42 hours per week) or prolonged standing (over 6 hours per day) (Saurel-Cubizolles et al., 2004). Avoidance of weight extremes and good nutritional support are important. Although a study failed to show that multivitamin preparation taken prior to conception reduces the risk of preterm birth, preconceptional intake of folic acid is recommended to reduce birth defects (Czeizel et al., 1994). There is significant evidence that long term (> one year) use of folic acid supplement preconceptionally may reduce premature birth. (Nano, 2008 and Engel et al., 2006). Reducing smoking is expected to benefit pregnant women and their offspring (Iams et al., 2008).
During pregnancy
Interventions that should have been initiated prior to pregnancy can still be instituted during pregnancy, including nutritional adjustments, use of vitamin supplements, and smoking cessation (Iams et al., 2008). Calcium supplementation as well as supplemental intake of C and E vitamins could not be shown to reduce preterm birth rates (Hofmeyr et al., 2006 and Rumbold et al., 2006). While periodontal infection has been linked with preterm birth, randomized trials have not shown that periodontal care during pregnancy reduces preterm birth rates (Iams et al., 2008).
Screening of low risk women
Screening for asymptomatic bacteriuria followed by appropriate treatment reduces pyelonephritis and reduces the risk of preterm birth (Romero et al., 1989).
Routine ultrasound examination of the length of the cervix identifies patients at risk, but cerclage is not proven useful, and the application of a progesterone is under study (Iams et al., 2008). Screening for the presence of fibronectin in vaginal secretions is not recommended at this time in women at low risk (Lu et al., 2001).
Self-care
Self-care methods to reduce the risk of preterm birth include proper nutrition, avoiding stress, seeking appropriate medical care, avoiding infections, and the control of preterm birth risk factors (e.g. working long hours while standing on feet, carbon monoxide exposure, , and other factors). Self-monitoring vaginal pH followed by yogurt treatment or clindamycin treatment if the pH was too high all seem to be effective at reducing the risk of preterm birth (Lamont and Jaggat, 2007).
Secondary (reducing existing risks)
Patients with certain uterine anomalies may have a surgical correction (i.e. removal of a uterine septum) (Acien, 1993), and those with certain medical problems can be helped by optimizing medical therapies prior to conception, be it for asthma, diabetes, hypertension and others (Banhidy et al., 2007).
During pregnancy
Reducing indicated preterm birth
Trials using low-dose aspirin, fish oil, vitamin C and E, and calcium to reduce preeclampsia demonstrated some reduction in preterm birth only when low-dose aspirin was used. Interestingly, even if agents such as calcium or antioxidants were able to reduce preeclampsia, a resulting decrease in preterm birth was not observed (Iams et al., 2008).
Reducing spontaneous preterm birth
Reduction in maternal activity – pelvic rest, limited work, bed rest – is frequently recommended although there is no clear proof of its efficacy. Also, increasing medical care by more frequent visits and more education has not shown a reduction in preterm birth rates (Hodnett and Fredericks, 2003). Use of nutritional supplements such as omega-3 polyunsaturated fatty acids reduce the risk of preterm birth, presumably as these agents inhibit production of proinflammatory cytokines (Olsen et al., 2000).
Antibiotics
Studies examining the use of antibiotics have provided mixed results; a Cochrane review of 15 trials shows no major benefit (McDonald et al., 2007) in contrast a review by Lamont, 2005 suggested that treatment of bacterial vaginosis if initiated prior to 20 w gestation is beneficial.
Progesterone
Progesterone, often given in the form of 17-hydroxyprogesterone caproate, relaxes the uterine musculature, maintains cervical length, and has anti-inflammatory properties, and thus exerts activities expected to be beneficial in reducing preterm birth (Dodd et al., 2006 and Mackenzie et al., 2006).
Cervical Cerclage
Instead of a prophylactic cerclage, women at risk can be monitored during pregnancy by sonography, and when shortening of the cervix is observed, the cerclage can be performed (Iams et al., 2008).
Numerous studies have been performed to assess the value of cervical cerclage and the procedure appears helpful primarily for women with a short cervix and a history of preterm birth (Berghella et al., 2005).
Management
Treatments to arrest early labour where there is progressive cervical dilatation and effacement will not be effective to gain sufficient time to allow the fetus to grow and mature further, it may defer delivery sufficiently to allow the mother to be brought to a specialized center that is equipped and staffed to handle preterm deliveries (Phibbs et al., 2007).
Glucocorticosteroids
Severely premature infants may have underdeveloped lungs, because they are not yet producing their own surfactant. This can lead directly to respiratory distress syndrome, also called hyaline membrane disease, in the neonate (Roberts and Dalziel, 2006). To try to reduce the risk of this outcome, pregnant mothers with threatened premature delivery prior to 34 weeks are often administered at least one course of glucocorticoids, a steroid that crosses the placental barrier and stimulates the production of surfactant in the lungs of the fetus (Stathis et al., 1999).
There is no research consensus on the efficacy and side-effects of a second course of steroids, but the consequences of RDS are so severe that a second course is often viewed as worth the risk (Vermillion et al., 2001). Beside reducing respiratory distress, other neonatal complications are reduced by the use of glucocorticosteroids, namely intraventricular haemorrhage, necrotising enterocolitis, and patent ductus arteriosus (Roberts and Dalziel, 2006).
Clinical research conducted in 2004 has shown that the postnatal administration of dexamethasone can lead to permanent neuromotor and cognitive deficits (Yeh, 2004).
In addition, a recent large scale study has found that a second “rescue” dose of betamethasone prenatally does not improve preterm birth outcomes and leads to decreased weight, length, and head circumference (Murphy et al., 2008). Other side effects of corticosteroids are diabetes mellitus, osteoporosis, inhibition of growth, hypertension, cognitive problems, anxiety, depression, gastritis, and colitis. Despite these concerns, there is a consensus that the benefits of a single regimen of prenatal glucocorticosteroids vastly outweigh the potential risks (Noguchi et al., 2008).
Tocolysis
Anti-contraction medications (tocolytics), such as Beta2-agonist drugs ritodrine, terbutaline (no longer approved by the FDA as a tocolytic), fenoterol, calcium-channel blockers (nifedipine), and oxytocin antagonists (atosiban) appear only to have a temporary effect in delaying delivery, just gaining 48 hours is sufficient to allow the pregnant women to be transferred to a center specialized for management of preterm deliveries and be given corticosteroids (Iams et al., 2008). Meta-analyses indicate that calcium-channel blockers and an oxytocin antagonist can delay delivery by 2–7 days, and β2-agonist drugs delay by 48 hours (Iams et al., 2008 and Li et al., 2005). Meta-analyses of magnesium sulfate failed to support it as a tocolytic agent (Simhan and Caritis, 2007).
Neonatal care
In developed countries premature infants are usually cared for in a neonatal intensive care unit (NICU). In the NICU, premature babies are kept under radiant warmers or in incubators (also called isolettes), which are designed to keep them warm and limit their exposure to germs. Modern neonatal intensive care involves sophisticated measurement of temperature, respiration, cardiac function, oxygenation, and brain activity. Treatments may include fluids and nutrition through intravenous catheters, oxygen supplementation, mechanical ventilation support, and medications (Phibbs et al., 2007).
A recent study on extremely premature infants (23-24 weeks) treated prophylactically with indomethacin within 6 hours of life showed a relative risk reduction (RRR) of developing symptomatic PDA (bounding pulses, wide pulse pressure, pulmonary congestion) to be 100% when compared to infants who were not given indomethacin until ductus-related signs were observed (Yoshimoto et al., 2010).
Prognosis
As survival has improved, the focus of interventions directed at the newborn has shifted to reduce long-term disabilities, particularly those related to brain injury (Saigal and Doyle, 2008). Some of the complications related to prematurity may not be apparent until years after the birth. A long-term study demonstrated that the risks of medical and social disabilities extend into adulthood and are higher with decreasing gestational age at birth and include cerebral palsy, mental retardation, disorders of psychological development, behavior, and emotion, disabilities of vision and hearing, and epilepsy (Moster et al., 2008). Studies of people born premature and investigated later with MRI brain imaging, demonstrate qualitative anomalies of brain structure and grey matter deficits within temporal lobe structures and the cerebellum that persist into adolescence (Spencer et al., 2011). Throughout life they are more likely to require services provided by physical therapists, occupational therapists, or speech therapists (Saigal nd Doyle, 2008).