Small for gestational age

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Small for gestational age
Weight vs gestational Age.jpg
Graph showing which babies fit the definition of small. (DiseaseDB #31952)
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Small for gestational age (SGA) newborns are those who are smaller in size than normal for the gestational age. SGA is most commonly defined as a weight below the 10th percentile for the gestational age. [1] SGA predicts susceptibility to hypoglycemia, hypothermia, and polycythemia. [2] By definition, at least 10% of all newborns will be labeled SGA. All SGA babies should be watched for signs of failure to thrive, hypoglycemia and other health conditions.

Contents

Causes

Being small for gestational age is broadly either: [3]

Diagnosis

The condition is defined by birth weight and/or length.

Intrauterine growth restriction is generally diagnosed by measuring the mother's uterus, with the fundal height being less than it should be for that stage of the pregnancy. If it is suspected, the mother will usually be sent for an ultrasound to confirm.[ citation needed ]

Management

Ninety percent of babies born SGA catch up in growth by the time they reach two years old. For the ten percent of those without catchup growth by two years old, an endocrinologist should be consulted. Some cases warrant growth hormone therapy.

Hypoglycemia is common in asymmetrical SGA babies because their larger brains burn calories at a faster rate than their usually limited fat stores hold.[ citation needed ] Hypoglycemia is treated by frequent feedings and/or additions of cornstarch-based products (such as Duocal powder) to the feedings.

Some common conditions and disorders found in many that are SGA (and especially those without catchup growth by two years old).

For intrauterine growth restriction (during pregnancy), possible treatments include the early induction of labor, though this is only done if the condition has been diagnosed and seen as a risk to the health of the fetus.[ citation needed ]

Terminology

If small for gestational age babies have been the subject of intrauterine growth restriction, formerly known as intrauterine growth retardation, [5] the term "SGA associated with intrauterine growth restriction" is used. Intrauterine growth restriction refers to a condition in which a fetus is unable to achieve its genetically determined potential size. This functional definition seeks to identify a population of fetuses at risk for modifiable but otherwise poor outcomes. This definition intentionally excludes fetuses that are small for gestational age (SGA) but are not pathologically small. [3] Infants born SGA with severe short stature (or severe SGA) are defined as having a length less than 2.5 standard deviation scores below the mean. [6]

A related term is low birth weight, defined as an infant with a birth weight (that is, mass at the time of birth [7] ) of less than 2500 g (5 lb 8 oz), regardless of gestational age at the time of birth. Other related terms include "very low birth weight", which is less than 1500 g, and "extremely low birth weight", which is less than 1000 g. [8] Normal weight at term delivery is 2500 g–4200 g.

SGA is not a synonym of low birth weight, very low birth weight, or extremely low birth weight. For example with a 35-week gestational age delivery, 2250 g weight is appropriate for gestational age but is still low birth weight. One third of low-birth-weight neonates – infants weighing less than 2500 g – are small for gestational age.

There is an 8.1% incidence of low birth weight in developed countries, and 6–30% in developing countries. Much of this can be attributed to the health of the mother during pregnancy. One third of babies born with a low birth weight are also small for gestational age. Infants that are born at low birth weights are at risk of developing neonatal infection.[ citation needed ]

Both low and high maternal serum Vitamin D (25-OH) are associated with higher incidence SGA in white women, although the correlation does not seem to hold for African American women. [9]

Mean weight for gestational age at birth with standard deviation and 10th percentile calculated by Z-score [10]
Gestational age at birth (weeks)Mean weight (grams)SD10th%
2246792354
23553109416
24626129473
25714156529
26819186597
27935215677
281073242770
291211269882
3013963091018
3115883361166
3218003711335
3320334051538
3422964281772
3525604402021
3627994412261
3730284562477
3832094322665
3933334192810
4034174162904
4134864222958
4235124292985
4335504442981
4435055032952

Related Research Articles

<span class="mw-page-title-main">Intrauterine growth restriction</span> Medical condition

Intrauterine growth restriction (IUGR), or fetal growth restriction, refers to poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's birth weight percentile. The causes of IUGR are broad and may involve maternal, fetal, or placental complications.

<span class="mw-page-title-main">Stillbirth</span> Death of a fetus before or during delivery, resulting in delivery of a dead baby

Stillbirth is typically defined as fetal death at or after 20 or 28 weeks of pregnancy, depending on the source. It results in a baby born without signs of life. A stillbirth can often result in the feeling of guilt or grief in the mother. The term is in contrast to miscarriage, which is an early pregnancy loss, and Sudden Infant Death Syndrome, where the baby dies a short time after being born alive.

Fetal distress, also known as non-reassuring fetal status, is a condition during pregnancy or labor in which the fetus shows signs of inadequate oxygenation. Due to its imprecision, the term "fetal distress" has fallen out of use in American obstetrics. The term "non-reassuring fetal status" has largely replaced it. It is characterized by changes in fetal movement, growth, heart rate, and presence of meconium stained fluid.

Oligohydramnios is a medical condition in pregnancy characterized by a deficiency of amniotic fluid, the fluid that surrounds the fetus in the abdomen, in the amniotic sac. It is typically diagnosed by ultrasound when the amniotic fluid index (AFI) measures less than 5 cm or when the single deepest pocket (SDP) of amniotic fluid measures less than 2 cm. Amniotic fluid is necessary to allow for normal fetal movement, lung development, and cushioning from uterine compression. Low amniotic fluid can be attributed to a maternal, fetal, placental or idiopathic cause and can result in poor fetal outcomes including death. The prognosis of the fetus is dependent on the etiology, gestational age at diagnosis, and the severity of the oligohydramnios.

Fetal viability is the ability of a human fetus to survive outside the uterus. Medical viability is generally considered to be between 23 and 24 weeks gestational age. Viability depends upon factors such as birth weight, gestational age, and the availability of advanced medical care. In low-income countries, half of newborns born at or below 32 weeks gestational age died due to a lack of medical access; in high-income countries, the vast majority of newborns born above 24 weeks gestational age survive.

In obstetrics, gestational age is a measure of the age of a pregnancy taken from the beginning of the woman's last menstrual period (LMP), or the corresponding age of the gestation as estimated by a more accurate method, if available. Such methods include adding 14 days to a known duration since fertilization, or by obstetric ultrasonography. The popularity of using this measure of pregnancy is largely due to convenience: menstruation is usually noticed, while there is generally no convenient way to discern when fertilization or implantation occurred.

<span class="mw-page-title-main">Large for gestational age</span> Medical condition

Large for gestational age (LGA) is a term used to describe infants that are born with an abnormally high weight, specifically in the 90th percentile or above, compared to other babies of the same developmental age. Macrosomia is a similar term that describes excessive birth weight, but refers to an absolute measurement, regardless of gestational age. Typically the threshold for diagnosing macrosomia is a body weight between 4,000 and 4,500 grams, or more, measured at birth, but there are difficulties reaching a universal agreement of this definition.

<span class="mw-page-title-main">Low birth weight</span>

Low birth weight (LBW) is defined by the World Health Organization as a birth weight of an infant of 2,499 g or less, regardless of gestational age. Infants born with LBW have added health risks which require close management, often in a neonatal intensive care unit (NICU). They are also at increased risk for long-term health conditions which require follow-up over time.

<span class="mw-page-title-main">Birth weight</span> Weight of a human baby at birth

Birth weight is the body weight of a baby at its birth. The average birth weight in babies of European and African descent is 3.5 kilograms (7.7 lb), with the normative range between 2.5 and 4.0 kilograms. On average, babies of Asian descent weigh about 3.25 kilograms (7.2 lb). The prevalence of low birth weight has changed over time. Trends show a slight decrease from 7.9% (1970) to 6.8% (1980), then a slight increase to 8.3% (2006), to the current levels of 8.2% (2016). The prevalence of low birth weights has trended slightly upward from 2012 to the present.

Prenatal development includes the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal development until birth.

<span class="mw-page-title-main">Complications of pregnancy</span> Medical condition

Complications of pregnancy are health problems that are related to, or arise during pregnancy. Complications that occur primarily during childbirth are termed obstetric labor complications, and problems that occur primarily after childbirth are termed puerperal disorders. While some complications improve or are fully resolved after pregnancy, some may lead to lasting effects, morbidity, or in the most severe cases, maternal or fetal mortality.

<span class="mw-page-title-main">Diabetes and pregnancy</span> Effects of pre-existing diabetes upon pregnancy

For pregnant women with diabetes, some particular challenges exist for both mother and fetus. If the pregnant woman has diabetes as a pre-existing disorder, it can cause early labor, birth defects, and larger than average infants. Therefore, experts advise diabetics to maintain blood sugar level close to normal range about 3 months before planning for pregnancy.

<span class="mw-page-title-main">Intrauterine hypoxia</span> Medical condition when the fetus is deprived of sufficient oxygen

Intrauterine hypoxia occurs when the fetus is deprived of an adequate supply of oxygen. It may be due to a variety of reasons such as prolapse or occlusion of the umbilical cord, placental infarction, maternal diabetes and maternal smoking. Intrauterine growth restriction may cause or be the result of hypoxia. Intrauterine hypoxia can cause cellular damage that occurs within the central nervous system. This results in an increased mortality rate, including an increased risk of sudden infant death syndrome (SIDS). Oxygen deprivation in the fetus and neonate have been implicated as either a primary or as a contributing risk factor in numerous neurological and neuropsychiatric disorders such as epilepsy, attention deficit hyperactivity disorder, eating disorders and cerebral palsy.

Placental insufficiency or utero-placental insufficiency is the failure of the placenta to deliver sufficient nutrients to the fetus during pregnancy, and is often a result of insufficient blood flow to the placenta. The term is also sometimes used to designate late decelerations of fetal heart rate as measured by cardiotocography or an NST, even if there is no other evidence of reduced blood flow to the placenta, normal uterine blood flow rate being 600mL/min.

<span class="mw-page-title-main">Triploid syndrome</span> Chromosomal disorder in which there are three copies of every chromosome

Triploid syndrome, also called triploidy, is a chromosomal disorder in which a fetus has three copies of every chromosome instead of the normal two. If this occurs in only some cells, it is called mosaic triploidy and is less severe.

A fetus or foetus is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal development begins from the ninth week after fertilization and continues until birth. Prenatal development is a continuum, with no clear defining feature distinguishing an embryo from a fetus. However, a fetus is characterized by the presence of all the major body organs, though they will not yet be fully developed and functional and some not yet situated in their final anatomical location.

<span class="mw-page-title-main">Circumvallate placenta</span> Medical condition

Circumvallate placenta is a rare condition affecting about 1-2% of pregnancies, in which the amnion and chorion fetal membranes essentially "double back" on the fetal side around the edges of the placenta. After delivery, a circumvallate placenta has a thick ring of membranes on its fetal surface. Circumvallate placenta is a placental morphological abnormality associated with increased fetal morbidity and mortality due to the restricted availability of nutrients and oxygen to the developing fetus.

<span class="mw-page-title-main">Prenatal nutrition</span>

Prenatal nutrition addresses nutrient recommendations before and during pregnancy. Nutrition and weight management before and during pregnancy has a profound effect on the development of infants. This is a rather critical time for healthy development since infants rely heavily on maternal stores and nutrient for optimal growth and health outcome later in life.

Neonatal hypoglycemia occurs when the neonate's blood glucose level is less than the newborn's body requirements for factors such as cellular energy and metabolism. There is inconsistency internationally for diagnostic thresholds. In the US, hypoglycemia is when the blood glucose level is below 30 mg/dL within the first 24 hours of life and below 45 mg/dL thereafter. In the UK, however, lower and more variable thresholds are used. The neonate's gestational age, birth weight, metabolic needs, and wellness state of the newborn has a substantial impact on the neonates blood glucose level. There are known risk factors that can be both maternal and neonatal. This is a treatable condition. Its treatment depends on the cause of the hypoglycemia. Though it is treatable, it can be fatal if gone undetected. Hypoglycemia is the most common metabolic problem in newborns.

Anthropometry is defined as the scientific study of the human body measurements and proportions. These studies are generally used by clinicians and pathologists for adequate assessments of the growth and development of the fetus at any specific point of gestational maturity. Fetal height, fetal weight, head circumference (HC), crown to rump length (CR), dermatological observations like skin thickness etc. are measured individually to assess the growth and development of the organs and the fetus as a whole and can be a parameter for normal or abnormal development also including adaptation of the fetus to its newer environment.

References

  1. Small for gestational age (SGA) at MedlinePlus. Update Date: 8/4/2009. Updated by: Linda J. Vorvick. Also reviewed by David Zieve.
  2. Cunningham, F. Gary; Leveno, Kenneth J.; Bloom, Steven L.; Spong, Catherine Y.; Dashe, Jodi S.; Hoffman, Barbara L.; Casey, Brian M.; Sheffield, Jeanne S. (2013). Williams Obstetrics (24 ed.). New York, NY: McGraw-Hill Education.
  3. 1 2 Ross, Michael G. "eMedicine - Fetal Growth Restriction" . Retrieved 2010-02-25.
  4. Barker, D. J. P., ed. (1992). Fetal and infant origins of adult disease. London: British Medical Journal. ISBN   0-7279-0743-3.
  5. Dogra, Vikram S. "eMedicine - Intrauterine Growth Retardation" . Retrieved 2007-11-28.
  6. Clayton, PE; Cianfarani, S; Czernichow, P; Johannsson, G; Rapaport, R; Rogol, A (March 2007). "Management of the child born small for gestational age through to adulthood: a consensus statement of the International Societies of Pediatric Endocrinology and the Growth Hormone Research Society". The Journal of Clinical Endocrinology and Metabolism. 92 (3): 804–10. doi: 10.1210/jc.2006-2017 . hdl: 2108/45969 . PMID   17200164.
  7. Definitions Archived 2012-04-02 at the Wayback Machine from Georgia Department of Public Health. Date: 12/04/2008. Original citation: "Birthweight: Infant's weight recorded at the time of birth"
  8. Subramanian, KN Siva. "eMedicine - Extremely Low Birth Weight Infant" . Retrieved 2007-11-28.
  9. Bodnar, LM; Catov, JM; Zmuda, JM; Cooper, ME; Parrott, MS; Roberts, JM; Marazita, ML; Simhan, HN (May 2010). "Maternal serum 25-hydroxyvitamin D concentrations are associated with small-for-gestational age births in white women". Journal of Nutrition. 140 (5): 999–1006. doi:10.3945/jn.109.119636. PMC   2855265 . PMID   20200114.
  10. Talge, Nicole M.; Mudd, Lanay M.; Sikorskii, Alla; Basso, Olga (2014-05-01). "United States Birth Weight Reference Corrected For Implausible Gestational Age Estimates". Pediatrics. 133 (5): 844–853. doi:10.1542/peds.2013-3285. ISSN   0031-4005. PMID   24777216. S2CID   5895957.