High-Risk Newborn
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Small for Gestational Age
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What is small for gestational age (SGA)?
Small for gestational age (SGA) is a term used to describe a baby who is smaller than the usual amount for the number of weeks of pregnancy. SGA babies usually have birthweights below the 10th percentile for babies of the same gestational age. This means that they are smaller than 90 percent of all other babies of the same gestational age.
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Factors related to the developing baby (fetus): o
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SGA babies may appear physically and neurologically mature but are smaller than other babies of the same gestational age. SGA babies may be proportionately small (equally small all over) or they may be of normal length and size but have lower weight and body mass. SGA babies may be premature (born before 37 weeks of pregnancy), full term (37 to 41 weeks), or post term (after 42 weeks of pregnancy). What causes small for gestational age (SGA)?
Although some babies are small because of genetics (their parents are small), most SGA babies are small because of fetal growth problems that occur during pregnancy. Many babies with SGA have a condition called intrauterine growth restriction (IUGR). IUGR occurs when the fetus does not receive the necessary nutrients and oxygen needed for proper growth and development of organs and tissues. IUGR can begin at any time in pregnancy. Early-onset IUGR is often due to chromosomal abnormalities, maternal disease, or severe problems with the placenta. Late-onset growth restriction (after 32 weeks) is usually related to other problems.
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When the fetus does not receive enough oxygen o r nutrients during pregnancy, overall body and organs growth is limited, and tissue and organ cells may not grow as large or as numerous. Some of the conditions that cause SGA and IUGR restrict blood flow through the placenta. This can cause the fetus to receive less oxygen than normal, increasing the risks for the baby during pregnancy, delivery, and afterwards. Babies with SGA and/or IUGR may have problems at birth including the following: •
decreased oxygen levels
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low Apgar scores (an assessment that helps identify babies with difficulty adapting after delivery)
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meconium aspiration (inhalation of the first stools passed in utero) which can lead to difficulty breathing
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hypoglycemia (low blood sugar)
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difficulty maintaining normal body temperature
Maternal factors: o o o o o o o o
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multiple gestation (twins, triplets, etc.) infection birth defects chromosomal abnormality
Why is small for gestational age (SGA) a concern?
Some factors that may contribute to SGA and/or IUGR include the following: •
placental abruption (placenta detaches from the uterus) placenta previa (placenta attaches low in the uterus) infection in the tissues around the fetus
high blood pressure chronic kidney disease advanced diabetes heart or respiratory disease malnutrition, anemia infection substance use (alcohol, drugs) cigarette smoking
Factors involving the uterus and placenta: o
decreased blood flow in the uterus and placenta
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polycythemia (too many red blood cells)
How is small for gestational age (SGA) diagnosed?
The baby with SGA is often identified before birth. During pregnancy, a baby's size can be estimated in different ways. The height of the fundus (the top of a mother's uterus) can be measured from the pubic b one. This measurement in centimeters usually corresponds with the number of weeks of pregnancy after the 20th week. If the measurement is low for the number of weeks, the baby may be smaller than expected.
Although many SGA babies have low birthweight, they are not all premature and may not experience the problems of premature babies. Other SGA babies, especially those with IUGR, appear thin, p ale, and with loose, dry skin. The umbilical cord is often thin, and dull-looking rather than shiny and fat. They sometimes have a wide-eyed look. Other diagnostic procedures may include the following:
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Babies with SGA may be physically more mature than their small size indicates. But they may be weak and less able to tolerate large feedings or to stay warm. Treatment of the SGA baby may include: • •
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ultrasound Ultrasound (a test using sound waves to create a picture of internal structures) is a more accurate method of estimating fetal size. Measurements can be taken of the fetus' head and abdomen and compared with a growth chart to estimate fetal weight. The fetal abdominal circumference is a helpful indicator of fetal nutrition. Doppler flow Another way to interpret and diagnose IUGR during pregnancy is Doppler flow, which use sound waves to measure blood flow. The sound of moving blood produces wave-forms that reflect the speed and amount of the blood as it moves through a blood vessel. Blood vessels in the fetal brain and the umbilical cord blood flow can be checked with Doppler flow studies. mother's weight gain A mother's weight gain can also indicate a baby's size. Small maternal weight gains in pregnancy may correspond with a small baby gestational assessment Babies are weighed within the first few hours after birth. The weight is compared with the baby's gestational age and recorded in the medical record. The birthweight must be compared to the gestational age. Some physicians use a formula for calculating a baby's body mass to diagnose SGA.
Treatment of babies who are small for gestational age (SGA):
Specific treatment for SGA will be determined by your baby's physician based on: •
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your baby's gestational age, overall health, and medical history extent of the condition your baby's tolerance for specific medications, procedures, or therapies
expectations for the course of the condition your opinion or preference
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temperature controlled beds or incubators tube feedings (if the baby does not have a strong suck) checking for hypoglycemia (low blood sugar) through blood tests monitoring of oxygen levels
Babies who are SGA and are also premature may have additional needs including oxygen and mechanical help to breathe. Prevention of small for gestational age (SGA):
Prenatal care is important in all pregnancies, and especially to identify problems with fetal growth. Stopping smoking and use of substances such as drugs and alcohol are essential to a healthy pregnancy. Eating a healthy diet in p regnancy may also help. [wikipEdiA]
Small for gestational age Small for gestational age (SGA) babies are those whose birth whose birth weight lies below the 10th percentile 10th percentile for that gestational age. age. They have usually been the subject of intrauterine growth restriction (IUGR), formerly known as intrauterine growth retardation.[1] Low birth weight (LBW) is sometimes used synonymously with SGA, or is otherwise defined as a fetus that weighs less than 2500 g (5 lb 8 oz) regardless of gestational age. Other definitions include Very Low Birth Weight (VLBW) which is less than 1500 g, and Extremely Low Birth Weight (ELBW) which is less than 1000 g. [2]
There is a 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 mother during during pregnancy pregnancy.. One third of babies born with a low birth weight are also small for gestational age. Diagnosis
The condition is generally diagnosed by measuring the mother's uterus uterus,, with the fundal height being 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.
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[edit edit]] Predetermining factors
The risk factor/etiology can be broadly divided into 3 categories• • •
Fetal Maternal Placental
The primary risk factor is that development of the placenta is insufficient to meet the demands of the fetus, resulting in malnutrition of the developing fetus. There are numerous contributing factors, of both environmental and genetic origin: •
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Environmental factors such as poor nutrition, tobacco smoking, smoking, drug addiction or alcoholism or alcoholism Severe anaemia (although hydrops may also occur) Thrombophilia (tendency for thrombosis for thrombosis)) Prolonged pregnancy Pre-eclampsia Chromosomal abnormalities Damaged or reduced placental tissue due to: Chronic renal failure o Sickle cell anemia o Phenylketonuria o Infections such as rubella rubella,, cytomegalovirus cytomegalovirus,, toxoplasmosis or syphilis or syphilis Twins and multiple births. births.
[edit edit]] Categories of growth restriction
There are two distinct categories of growth restriction, indicating the stage at which the development was slowed. Small for gestational age babies can be classified as having symmetrical or asymmetrical [3][4] 4] [asymmetrical] growth restriction. restriction.[3][ [edit edit]] Symmetrical Symmetrical growth restriction , less commonly known as global growth restriction , indicates that the fetus has developed slowly throughout the duration of the pregnancy and was thus affected from a very early stage. The head circumference of such a newborn is in proportion to the rest of the body. Common causes include: •
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Early intrauterine infections, such as cytomegalovirus,, rubella or toxoplasmosis cytomegalovirus or toxoplasmosis Chromosomal abnormalities
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Chronic high blood pressure Severe malnutrition Anemia Maternal substance abuse (prenatal alcohol use can result in Fetal alcohol syndrome) syndrome)
Asymmetrical Asymmetrical growth restriction occurs when the embryo//fetus has grown normally for the first two embryo trimesters but trimesters but encounters difficulties in the third, usually pre-eclampsia. Such babies have a disparity in their length and head circumference when compared to the birth weight. A lack of subcutaneous of subcutaneous fat leads to a thin and small body out of proportion with the head. Other symptoms include dry, peeling skin and an overly-thin umbilical cord, cord, and the baby is at increased risk of hypoxia of hypoxia and hypoglycaemia hypoglycaemia.. Treatment
Possible treatments include the early induction of labour, though this is only done if the condition has been diagnosed and seen as a risk to the health of the fetus.
