Low Birth Weight during Pregnancy (IUGR)
Small-for gestational age (SGA) or intrauterine growth restriction (IUGR) are medical terms for low birth weight during pregnancy. Fetal weight that is below the 10th percentile for gestational age as determined through an ultrasound may be diagnosed as an IUGR. During pregnancy, your doctor will assess how much your baby is growing by estimating the size and weight of your baby. If your baby is estimated to weigh less than most other babies of the same gender who are at the same stage of development, it is called a low birth weight. It means that when she is born, your baby is likely to be smaller than most other babies.
There are two types of fetal growth restrictions:
- Symmetric or primary growth restriction: Characterized by all internal organs being reduced in size, symmetric growth restriction accounts for 20% to 25% of all cases of IUGR.
- Asymmetric or secondary growth restriction: Here the head and brain are normal in size, but the abdomen is smaller. Typically this may not be evident until the third trimester.
Who is at risk for low birth weight during pregnancy?
- Women with a maternal weight of less than 100 pounds
- Poor nutrition during pregnancy
- Birth defects or chromosomal abnormalities
- Use of drugs, cigarettes, and/or alcohol
- Pregnancy induced hypertension (PIH)
- Placental abnormalities
- Umbilical cord abnormalities
- Multiple pregnancy
- Gestational diabetes in the mother
- Low levels of amniotic fluid or oligohydramnios
- Preeclampsia, which reduces blood flow to your baby
- Stress (Rogers and Piecuch 2009)
How is IUGR diagnosed?
Accurate dating of your pregnancy (gestational age) is one of the most important factors considered when diagnosing fetal growth restriction. Gestational age can be calculated by using the first day of your last menstrual period (LMP) and also by early ultrasound calculations. Once this is established, the following methods may be used to diagnose IUGR:
- Fundal height that does not coincide with gestational age
- Ultrasound measurements that are smaller than expected for the gestational age
- Abnormal findings discovered by a Doppler ultrasound
How is fetal growth restriction treated?
The treatment usually depends on how far along you are in your pregnancy.
- If gestational age is 34 weeks or greater, health care providers may recommend being induced for an early delivery.
- When the gestational age is less, health care providers will continue monitoring fetal well-being and the amount of amniotic fluid until 34 weeks or beyond. If either of these becomes a concern, then immediate delivery may be recommended.
- You may have appointments every 2 to 6 weeks until you deliver. If delivery is suggested prior to 34 weeks, your health care provider may perform an amniocentesis to help evaluate fetal lung maturity.
What are the risks to a baby with low birth weight?
- An increased risk for cesarean delivery
- Increased risk for hypoxia (lack of oxygen when the baby is born)
- Increased risk for meconium aspiration, which is when the baby swallows part of the first bowel movement. This can cause the alveoli to be over distended, a pneumothorax to occur, and/or the baby can develop bacterial pneumonia.
- Hypoglycemia (low blood sugar)
- Polycythemia (increased number of red blood cells)
- Hyperviscosity (decreased blood flow due to an increased number of red blood cells)
- Increased risk for motor and neurological disabilities
Lowering the risk of IUGR
There are many positive steps you can take to give your baby to have a healthy start.
- If you have diabetes or high blood pressure it is important to work with your doctor to control it
- Limit drinking to two units of alcohol, once or twice a week, or stop drinking alcohol completely
- Eat a healthy, balanced diet, and maintain a healthy weight
- Seek help if you think you might have a problem with drugs
- Stop smoking
If your pregnancy is high risk it is best to consult a perinatologist who has specialized training to provide the right kind of prenatal care.
Dr. Jorge L. Gomez earned his Medical Degree in 1990 at Central Del Caribe University in Bayamon, Puerto Rico. Following residency in Obstetrics and Gynecology at Bronx-Lebanon Hospital center in the Bronx, NY (1990–1994), he completed additional fellowship training at New York University Medical Center NY, specializing in Maternal Fetal Medicine (1994-1996). After his fellowship in 1996 he joined South Florida Perinatal Medicine. Dr. Gomez is Board certified in OBGYN and Maternal Fetal Medicine. From 2003–2007 He was a reviewer for the American Journal Of Obstetrics and Gynecology.