Beckman: Chpt. 14 Fetal Growth Abnormalities:
Intrauterine Growth Restriction and
Macrosomia(Correct answers)
Intrauterine Growth Restriction correct answersThe designation given to a fetus or infant whose
weight is less than the 10th percentile of a specific population at a given gestational age.
Small for gestational age correct answersthe term used to describe an infant with a birth weight
at the lower extreme of the normal birth weight distribution. In the U.S. the most commonly used
definition is a birth weight below the 10th percentile for gestational age.
Growth Descriptor: Low birth weight correct answers<2,500 g
Growth Descriptor: Intrauterine growth restriction correct answers<10%
Growth descriptor: Macrosomia correct answers>4,500 g
growth descriptor: large for gestational age correct answers>90%
Short term significance for the growth restricted fetus: correct answersThe growth restricted
fetus potentially lacks adequate reserves to continue intrauterine existence, to undergo the stress
of labor, and to fully adapt to neonatal life. These conditions make the infant vulnerable to
intrauterine fetal death, asphyxia, acidemia, and intolerable labor.
Neonatal complications for IUGR correct answerslow apgar scores, polycythemia,
hyperbilirubinemia, hypoglycemia, hypothermia, apnea, respiratory distress, seizures, sepsis,
meconium aspiration, and neonatal death
The smaller the fetus, the greater its risk for mobidity and mortality correct answersPerinatal
morbidity and mortality are significantly increased, especially with weights below the third
percentile for gestational age. ~26% of stillbirths are SGA
Cellular hyperplasia correct answersThe primary means of fetal growth in early pregnancy. Early
onset of IUGR may lead to an irreversible diminution of organ size and perhaps function.
Cellular hypertrophy correct answersLater in pregnancy, fetal growth relies on both cellular
hypertrophy and hyperplasia. Delayed onset IUGR may result in decreased cell size, which may
be more amenable to restoration of fetal size with adequate nutrition.
Placental Growth correct answersthe placenta grows early and rapidly compared with the fetus,
reaching a maximum surface area of about 11 meters squared and 500g at ~ 37 weeks.
Thereafter, there is a slow but steady decline in placental surface area (and hence, function),
primarily because of microinfarctions of its vascular system.
, Uteroplacental insufficiency correct answerslate-onset grwoth restriction may be a result of the
decline in function of the placenta past 37 weeks related to the microinfarctions.
Risk factors associated with IUGR correct answers- maternal medications
- hypertension
- renal disease
- restrictive lung disease
- diabetes (with microvascular disease)
- cyanotic heart disease
- antiphospholipid syndrome
- collagen vascular disease
- hemoglobinopathies
- smoking and substance use/abuse
- severe malnutrition
- primary placental disease
- multiple gestation
- infections (viral and protozoal) (5% or fewer of cases are related to early infection with viral
infections such as rubella, varicella, and cytomegalovirus)
- genetic disorders
- exposure to teratogens
Maternal Factors associated with IUGR correct answers- substance abuse, fetal alcohol
syndrome
--> women who use narcotics, heroin, methadone, or cocaine have rates of GR babies of 30-50%
- smoking (200g smaller on average)
- medications: anticonvulsant medications, warfarin, folic acid antagonists
- altitude may also affect fetal growth
- maternal metabolism and body composition are two of the strongest regulators of fetal growth
- nutritional deficiencies or inadequate weight gain, particularly in teens and underweight women
may result in IUGR
Fetal Factors Associated with IUGR correct answers- the inherent growth potential of the
individual is determined genetically.
- Female fetuses are > risk than males
- 5% growth restricted fetuses have a chromosomal abnormality
- single gene mutations (e.g. glucokinase gene mutation)
- structural malformations (e.g. gastroschisis and renal agenesis)
Placental factors associated with IUGR correct answersAbnormalities in placentation or
defective trophoblast invasion and remodeling may contribute to fetal growth restriction as well
as other disorders of pregnancy.
- fibroids or uterine septum can affect placentation
- confined placental mosaicism is associated with growth delay
Diagnosis of IUGR correct answersAntenatal recognition of IUGR depends on the recognition of
risk factors and the clinical assessment of uterine size, followed by biometric measurements
Intrauterine Growth Restriction and
Macrosomia(Correct answers)
Intrauterine Growth Restriction correct answersThe designation given to a fetus or infant whose
weight is less than the 10th percentile of a specific population at a given gestational age.
Small for gestational age correct answersthe term used to describe an infant with a birth weight
at the lower extreme of the normal birth weight distribution. In the U.S. the most commonly used
definition is a birth weight below the 10th percentile for gestational age.
Growth Descriptor: Low birth weight correct answers<2,500 g
Growth Descriptor: Intrauterine growth restriction correct answers<10%
Growth descriptor: Macrosomia correct answers>4,500 g
growth descriptor: large for gestational age correct answers>90%
Short term significance for the growth restricted fetus: correct answersThe growth restricted
fetus potentially lacks adequate reserves to continue intrauterine existence, to undergo the stress
of labor, and to fully adapt to neonatal life. These conditions make the infant vulnerable to
intrauterine fetal death, asphyxia, acidemia, and intolerable labor.
Neonatal complications for IUGR correct answerslow apgar scores, polycythemia,
hyperbilirubinemia, hypoglycemia, hypothermia, apnea, respiratory distress, seizures, sepsis,
meconium aspiration, and neonatal death
The smaller the fetus, the greater its risk for mobidity and mortality correct answersPerinatal
morbidity and mortality are significantly increased, especially with weights below the third
percentile for gestational age. ~26% of stillbirths are SGA
Cellular hyperplasia correct answersThe primary means of fetal growth in early pregnancy. Early
onset of IUGR may lead to an irreversible diminution of organ size and perhaps function.
Cellular hypertrophy correct answersLater in pregnancy, fetal growth relies on both cellular
hypertrophy and hyperplasia. Delayed onset IUGR may result in decreased cell size, which may
be more amenable to restoration of fetal size with adequate nutrition.
Placental Growth correct answersthe placenta grows early and rapidly compared with the fetus,
reaching a maximum surface area of about 11 meters squared and 500g at ~ 37 weeks.
Thereafter, there is a slow but steady decline in placental surface area (and hence, function),
primarily because of microinfarctions of its vascular system.
, Uteroplacental insufficiency correct answerslate-onset grwoth restriction may be a result of the
decline in function of the placenta past 37 weeks related to the microinfarctions.
Risk factors associated with IUGR correct answers- maternal medications
- hypertension
- renal disease
- restrictive lung disease
- diabetes (with microvascular disease)
- cyanotic heart disease
- antiphospholipid syndrome
- collagen vascular disease
- hemoglobinopathies
- smoking and substance use/abuse
- severe malnutrition
- primary placental disease
- multiple gestation
- infections (viral and protozoal) (5% or fewer of cases are related to early infection with viral
infections such as rubella, varicella, and cytomegalovirus)
- genetic disorders
- exposure to teratogens
Maternal Factors associated with IUGR correct answers- substance abuse, fetal alcohol
syndrome
--> women who use narcotics, heroin, methadone, or cocaine have rates of GR babies of 30-50%
- smoking (200g smaller on average)
- medications: anticonvulsant medications, warfarin, folic acid antagonists
- altitude may also affect fetal growth
- maternal metabolism and body composition are two of the strongest regulators of fetal growth
- nutritional deficiencies or inadequate weight gain, particularly in teens and underweight women
may result in IUGR
Fetal Factors Associated with IUGR correct answers- the inherent growth potential of the
individual is determined genetically.
- Female fetuses are > risk than males
- 5% growth restricted fetuses have a chromosomal abnormality
- single gene mutations (e.g. glucokinase gene mutation)
- structural malformations (e.g. gastroschisis and renal agenesis)
Placental factors associated with IUGR correct answersAbnormalities in placentation or
defective trophoblast invasion and remodeling may contribute to fetal growth restriction as well
as other disorders of pregnancy.
- fibroids or uterine septum can affect placentation
- confined placental mosaicism is associated with growth delay
Diagnosis of IUGR correct answersAntenatal recognition of IUGR depends on the recognition of
risk factors and the clinical assessment of uterine size, followed by biometric measurements
