I. HIGH-RISK NEWBORNS are often associated with certain maternal, placental, or fetal conditions; when one or more are present, nursery staff should be aware and prepared for possible difficulties. The placenta should be saved in all cases of high-risk delivery, including cases that involve transfer from the birth hospital because an elusive diagnosis such as toxoplasmosis may be made on the basis of placental pathology. The following factors are associated with high-risk newborns:

a. Over 40 years. Chromosomal abnormalities, macrosomia, intrauterine growth retardation (IUGR), blood loss (abruption or previa)

b. Under 16 years. IUGR, preterm birth, child abuse/neglect (mother herself may be abused)

a. Poverty. Preterm birth, IUGR, infection

b. Smoking. Increased perinatal mortality, IUGR

c. Drug/alcohol use. IUGR, fetal alcohol syndrome, withdrawal syndrome, sudden infant death syndrome, child abuse/neglect

d. Poor diet. Ranges from mild IUGR to fetal demise with severe malnutrition

e. Trauma (acute, chronic). Fetal demise, abruptio placentae, preterm birth

a. Diabetes mellitus. Stillbirth, macrosomia/birth injury/IUGR in advanced stages with vascular insufficiency, respiratory distress syndrome (RDS), hypoglycemia, congenital anomalies (see Chapter 2)

b. Thyroid disease. Goiter, hypothyroidism, hyperthyroidism (see Chapter 61)

c. Renal disease. Stillbirth, IUGR, preterm birth

d. Urinary tract infection. Preterm birth, sepsis

e. Heart and/or lung disease. Stillbirth, IUGR, preterm birth

f. Hypertension (chronic or pregnancy-related). Stillbirth, IUGR, preterm birth, asphyxia, polycythemia, thrombocytopenia, leukopenia

g. Anemia. Stillbirth, IUGR, hydrops, preterm birth, asphyxia

h. Isoimmunization (red cell antigens). Stillbirth, hydrops, anemia, jaundice

i. Thrombocytopenia, including alloimmunization (platelet antigens). Stillbirth, bleeding including intracranial hemorrhage (ICH)

a. Past history of infant with preterm birth, jaundice, RDS, or anomalies. Same with current pregnancy

b. Maternal medications (see Appendix A and B)

c. Bleeding. Stillbirth, preterm birth, anemia

d. Hyperthermia. Fetal demise, fetal anomalies

e. Premature rupture of membranes. Infection/sepsis

f. Toxoplasmosis, other, rubella, cytomegalovirus, and herpes simplex (TORCH) infections (see Chapter 48)

1. Multiple gestation. IUGR, twin-twin transfusion syndrome, preterm birth, asphyxia, birth trauma

2. IUGR. Fetal demise, genetic abnormalities, congenital anomalies, asphyxia, hypoglycemia, polycythemia

3. LGA and/or macrosomia. Congenital anomalies, birth trauma, hypoglycemia

4. Abnormal fetal position/presentation. Congenital anomalies, birth trauma, hemorrhage

5. Abnormality of fetal heart rate or rhythm. Congestive heart failure, heart block, hydrops, asphyxia

6. Decreased activity. Fetal demise, neurologic abnormalities, asphyxia

7. Polyhydramnios. Anencephaly, other central nervous system (CNS) disorders, neuromuscular disorders, problems with swallowing (e.g., esophageal atresia, agnathia, any mass in the mouth), chylothorax, diaphragmatic hernia, omphalocele, gastroschisis, trisomy, tumors, hydrops, isoimmunization, anemia, cardiac failure, intrauterine infection,
maternal diabetes or other etiologies of inability to concentrate urine, LGA, preterm delivery

8. Oligohydramnios. Fetal demise, placental insufficiency, IUGR, renal agenesis, pulmonary hypoplasia, deformations, intrapartum distress, postterm delivery

1. Preterm delivery. RDS, other issues of preterm birth (see Chapter 13)

2. Postterm delivery (occurring >2 weeks after term). Stillbirth, asphyxia, meconium aspiration (see section IV)

3. Maternal fever. Infection/sepsis

4. Maternal hypotension. Stillbirth, asphyxia

5. Rapid labor. Birth trauma, ICH, retained fetal lung fluid/transient tachypnea

6. Prolonged labor. Stillbirth, asphyxia, birth trauma

7. Abnormal presentation. Birth trauma, asphyxia

8. Uterine tetany. Asphyxia

9. Meconium-stained amniotic fluid. Stillbirth, asphyxia, meconium aspiration syndrome, persistent pulmonary hypertension

10. Prolapsed cord. Stillbirth, asphyxia

11. Cesarean section. RDS, retained fetal lung fluid/transient tachypnea, blood loss

12. Obstetric analgesia and anesthesia. Respiratory depression, hypotension

a. Small placenta. IUGR

b. Large placenta. Hydrops, maternal diabetes, large infant

c. Torn placenta and/or umbilical vessels. Blood loss, anemia

d. Abnormal attachment of vessels to placenta. Blood loss, anemia

1. Preterm birth. RDS, other sequelae of preterm birth

2. Low 5-minute Apgar score. Prolonged transition (especially respiratory)

3. Low 10-minute Apgar score. Neurologic damage

4. Pallor or shock. Blood loss

5. Foul smell of amniotic fluid or membranes. Infection

6. SGA (see section V)

7. LGA (see section VI). Hypoglycemia, birth trauma, congenital anomalies

8. Postmaturity syndrome (see section IV)

II. GA AND BIRTH WEIGHT CLASSIFICATION. Neonates should be classified by GA, if at all possible, as this generally correlates more closely with outcomes
than birth weight does. Birth weight becomes significant if neonate is either SGA or LGA.

1. Assessment based on obstetric information is covered in Chapter 1. Note that GA estimates by first-trimester ultrasonography are accurate within 7 days. Second- and third-trimester ultrasounds are within approximately 11 to 14 and 21 days, respectively.

2. To confirm or supplement obstetric dating, the modified Dubowitz (Ballard) examination for newborns (Fig. 7.1) may be useful in GA estimation. There are limitations to this method, especially with use of the neuromuscular component in sick newborns.

a. Preterm are born at <37 completed weeks of gestation (258 days). Subgroups of preterm infant include the following:

i. Extremely preterm infants are born <28 weeks (195 days).

ii. Early preterm infants are born <34 weeks (237 days).

iii. Late preterm infants are born between 34 0/7 and 36 6/7 weeks of gestation (238 to 258 days).

b. Term infants are born between 37 0/7 and 41 6/7 weeks of gestation (259 to 293 days).

i. Early term infants are subgroup of term infants born between 37 0/7 and 38 6/7 weeks of gestation (259 to 272 days).

c. Postterm infants are born after 42 weeks of gestation (294 days) or more.

B. Birth weight classification. Although there is no universal agreement, the commonly accepted definitions are as follows:

1. Normal birth weight (NBW). From 2,500 to 4,000 g

2. Low birth weight (LBW). <2,500 g Note that, although most LBW infants are preterm, some are term but SGA. LBW infants can be further subclassified as follows:

a. Very low birth weight (VLBW). <1,500 g

b. Extremely low birth weight (ELBW). <1,000 g

III. PRETERM BIRTH. A preterm neonate is one who is born <37 weeks’ gestation (as noted earlier).

A. Incidence. Approximately 10% of all births in the United States are preterm. In 2014, the National Center for Health Statistics officially completed the transition to a new method of quantifying GA, shifting from the previous practice of counting from last menstrual period (LMP) to using best obstetric estimate (OE) of gestation at delivery. The 2014 preterm birth rate was 9.57%, down slightly from 9.62% in 2013. The percentage of births delivered preterm has declined 8% since 2007 (from 10.44%), the first year for which national OE data are available for this measure (and differs from the LMP-based rate previously published). The rate of infants born early preterm (<34 weeks) was down slightly, from 2.79% to 2.75% for 2013 to 2014; this rate of early preterm births has declined 6% since

2007. The late preterm birth rate (34 to 36 weeks) was essentially stable at 6.82% in 2014; this rate of late preterm birth has declined 9% since 2007.

B. Etiology is unknown in most cases. Preterm and/or LBW delivery is associated with the following conditions:

1. Low socioeconomic status (SES), whether measured by family income, educational level, geographic area/ZIP code, social class, and/or occupation

2. Non-Hispanic black women are more than three times as likely to deliver an extremely preterm infant (<28 weeks of gestation) compared with non-Hispanic white and Hispanic women. In 2014, the rate for non-Hispanic black women was 13.23% that, although significantly higher than that of non-Hispanic white and Hispanic women, has dropped from its peak of 18.3% in 2007. This disparity in very short gestation delivery by race/ethnicity contributes to the substantial black-white gap in infant mortality. Disparities persist even when SES is taken into account.

3. Women younger than 16 or older than 35 years are more likely to deliver preterm or LBW infants; the association with age is more significant in whites than in African Americans.

4. Maternal activity requiring long periods of standing or substantial amounts of physical stress may be associated with IUGR and preterm birth.

5. Acute or chronic maternal illness is associated with early delivery, whether onset of labor is spontaneous or, not infrequently, induced.

6. Multiple-gestation births frequently deliver preterm (57% of twins and 93% of triplets in the United States in 2013). In such births, the higher rate of neonatal mortality is primarily due to preterm birth.

7. Prior poor birth outcome is the single strongest predictor of poor birth outcome. A preterm first birth is the best predictor of a second preterm birth. One preterm birth increases the risk for a second fourfold.

8. Obstetric factors such as uterine malformations, uterine trauma, placenta previa, abruptio placentae, hypertensive disorders, preterm cervical shortening, previous cervical surgery, premature rupture of membranes, and chorioamnionitis also contribute to preterm birth.

9. Fetal conditions such as nonreassuring testing of fetal well-being (see Chapter 1), IUGR, or severe hydrops may require preterm delivery.

10. Inadvertent early delivery because of incorrect estimation of GA is increasingly uncommon using the OE method.

C. Problems associated with preterm birth are related to difficulty in extrauterine function due to immaturity of organ system.

1. Respiratory. Preterm infants may experience the following:

a. Perinatal depression in the delivery room due to hypoxic ischemia perinatal conditions (see Chapter 55)

b. RDS due to surfactant deficiency and pulmonary immaturity (see Chapter 33)

c. Apnea due to immaturity in mechanisms controlling breathing (see Chapter 31)

d. Eventual development of chronic lung disease (CLD) of prematurity also referred to as bronchopulmonary dysplasia (see Chapter 34)

2. Neurologic. Preterm infants have a higher risk of neurologic problems including the following:

a. Perinatal depression (see Chapter 55)

b. ICH (see Chapter 54)

c. Periventricular leukomalacia (see Chapter 54)

3. Cardiovascular. Preterm infants may present with cardiovascular problems including the following:

i. Hypovolemia

ii. Cardiac dysfunction

iii. Sepsis-induced vasodilation

b. Patent ductus arteriosus is common and may lead to pulmonary overcirculation and diastolic hypotension (see Chapter 41).

4. Hematologic. Conditions for which preterm infants are at higher risk include the following:

a. Anemia (see Chapter 45)

b. Hyperbilirubinemia (see Chapter 26)