Small for gestational age (SGA) babies are those whose birth weight lies below the 10th percentile for that gestational age. Low birth weight (LBW), is sometimes used to define a baby that weighs less than 5 lb 8 oz (2500 g) regardless of gestational age. One third of babies born with a low birth weight are also small for gestational age.
Other definitions include Very Low Birth Weight (VLBW) which is less than 3 lb 5 oz (1500 g), and Extremely Low Birth Weight (ELBW) which is less than 2 lb 3 oz (1000 g).
About 10 percent of fetuses are low birth weight. A health care provider may suspect fetal growth restriction if the mother's uterus measurement (fundal height) is lower than expected. This can be confirmed with a series of ultrasounds that will monitor how quickly the fetus is growing.
Measurements can be taken of the fetus' head and limbs and compared with a growth chart to estimate fetal weight. In some cases, fetal growth can be improved by treating any condition in the mother (such as high blood pressure) that may be a contributing factor.
The health care provider will closely monitor the well being of a growth restricted fetus using ultrasound and fetal heart rate monitoring. If these tests show that the baby is having problems, the baby may need to be delivered early.
The main causes for Low Birth Weight:
The two main causes of LBW are early delivery, also known as preterm birth, and poor fetal growth. About 70% of all LBW babies are born preterm - before 37 completed weeks of pregnancy. The remaining 30% of low birth weight babies are born at full term, but did not grow properly in the womb.
~ Some of the risk factors for preterm birth are:
Carrying more than one baby such as twins or triplets
Previous preterm birth
Smoking or exposure to second hand smoke
Stress and lack of support
Infection- some infections in pregnant women, such as bladder or vaginal infections, can cause labour to start early
Stressful work conditions such as
Being on your feet for long periods
Exposure to harmful substances
Poor Fetal Growth
~ Some reasons for this may be:
Use of alcohol, drugs & smoking - women who smoke are 2-3 times more likely to have a LBW baby
Exposure to second hand smoke can also contribute to LBW
Poor nutrition - women who do not gain at least 22lb (10 kg) are 2-3 times more likely to have a LBW baby
Being under weight before becoming pregnant
Mothers age at time of pregnancy - women under 20 and over 45 are more likely to have a LBW baby.
Stress, exhaustion or lack of rest
Abuse and /or family violence
Living in poverty
Fortunately, there are things that can be done to prevent some low birth weight babies.
Some of the simple things that can be done to decrease the chance of it happening are:
NO alcohol, drugs or smoking in pregnancy - and also before you get pregnant.
Eating a balanced diet - More fruit and vegatables, less of the junk foods.
Watch your weight - Eating for two is OK, but not double your usual amount.
Regular low impact exercise - Take a stroll around the park or go swimming.
Take time to relax - Put your feet up, read a book or knit those baby bootie