Intrauterine growth restriction (IUGR) is a condition in which the baby does not grow properly during its time in the mother’s womb. It is due to a mix of factors including disease conditions in the mother, genetic defects in the baby, and poor placental growth.
These babies may do worse than normal babies during the stress of labor, and if severely restricted in growth, may even die in the womb. For this reason, IUGR is a condition which should be properly diagnosed and treated.
The management of IUGR depends on the cause, if any is identified, and the stage of pregnancy at which the baby stops growing normally. This is because the greatest damage occurs when IUGR is seen from early pregnancy onwards, and such babies must be carefully monitored until their birth to make sure they don’t die in the womb. Following their delivery, many more tests may be needed to determine the type of follow-up care they need.
Antenatal Monitoring in IUGR
Before delivery, the caregiver needs to keep a careful eye on the baby. This is done by a set of tests:
- Fetal movement count: the mother should be taught to recognize the fetal movements and chart them daily. A significant change should trigger relevant testing to rule out physical distress in the baby.
- Nonstress testing (NST): This is a test which uses a machine to monitor the heart rate and record it, while the mother indicates when she feels a kick. Normally, each kick is linked to an increase in the heart rate, and lack of this variability may indicate a baby in distress.
- Biophysical profile (BPP): This test combines NST with ultrasound imaging of four items, namely, the amount of fluid around the baby, the breathing movements, the body movements and the baby’s muscular tone, to assess how well the baby is doing in the womb.
- Ultrasound scanning: This technology is used to generate a complete picture of the baby inside the womb, both the structure and function of the various organs and the placenta. Successive ultrasound scans help to monitor whether the baby is showing any growth and to determine the time when it would be better to deliver the baby, and how that delivery should be done.
- Doppler studies: Doppler is a special type of ultrasound, which is used to assess the variation in blood flow velocity through the blood vessels in the umbilical cord, which is linked to the placenta. A significant change in this flow may signal that placental supply to the baby is about to drop below critical levels and the baby is at risk of dying without delivery.
Antenatal Care in IUGR
Once IUGR is diagnosed, various treatments such as bed rest, increased or supplemental food intake to increase the baby’s weight, and treatment of any medical condition, may be recommended. Bed rest may improve circulation to the baby in some cases, though evidence is weak. Again, in women who are severely malnourished, better food may make some difference in the growth of the baby, but it is unlikely to benefit the baby who is not obtaining food because of a poorly functioning placenta.
The mother of an IUGR baby should stop habits such as smoking, drinking and taking drugs. Good food, rest and regular prenatal care may help to some extent to control some factors contributing to IUGR. Of course, this will also help to ensure the baby is born in a good environment where people are prepared to take care of a high-risk newborn.
Management of the Delivery Process
During the birth process, it is important to choose the type of delivery so that the baby does not suffer from birth asphyxia, or lack of oxygen during birth. If it is present it should be treated promptly but carefully.
When is Delivery Right?
If all the antenatal tests show that the baby is doing reasonably well and is still growing, the pregnancy is allowed to continue until term. Some centers provide a course of glucocorticoid injections in the period between 24 and 34 weeks so that the baby’s lungs can mature, if delivery becomes absolutely necessary before term. If the tests become abnormal, and especially if fetal growth stops altogether, delivery often becomes the only way out even if the baby is very preterm. Such a decision is taken after explaining all the risks associated with delivering a preterm baby and the risks of having a stillborn or severely asphyxiated (suffocated) baby if the pregnancy is allowed to continue.
A test involving the use of oxytocin, a drug which induces contractions of the uterus, is often carried out to see if the baby can tolerate this type of stress. However, many centers prefer a combined NST with a BPP if required.
The Right Place of Delivery
Considering the risk of birth asphyxia and other problems linked to a small and often preterm baby, the delivery should take place only in a center equipped to handle such babies and to offer emergency C-sections if required.
Management After Birth
The complete physical examination of the baby is important to try and identify the type of IUGR that the baby suffers from. This will record the birth weight, the head circumference, the mid-arm circumference, the abdominal circumference and the length. A baby who is small all over probably has a genetic defect or has acquired an infection in the womb, which has destroyed many of the baby’s cells. Such causes may also be identified by the presence of abnormal body features and physical defects. On the other hand, babies with a relatively large head and a widened body are probably suffering from lack of food more than anything else.
In addition, the baby should be tested for hypoglycemia (low blood sugar), because this leads to many other complications including breathing problems, infections, low body temperature and drop in blood calcium levels. Other tests which are usually done at this time include blood counts to detect infections and unduly high red cell count (polycythemia).
These babies should be given intravenous fluids carefully calculated to cover their needs, including the water lost by fast breathing to get more oxygen. They should be given a higher caloric intake as they grow to help them achieve catch-up growth, something like 100 kilocalories or more per kg per day. Regular assessments will help determine what areas of mental and physical development require special help.
IUGR babies often die at or soon after birth, with a death rate 5-20 times higher than normally grown infants. Much of this is due to death in the womb, suffocation during birth, and the presence of birth defects.
Many infants who were growth-restricted never do catch up, perhaps one in every three. This is probably due to the double stress of nutritional deprivation in the womb coupled with preterm birth. The toll is higher as the period in which the baby could grow in the womb becomes shorter, and also with lower birth weights.
Neurologic damage occurs 5-10 times more often in these babies, with obvious learning deficits, short attention spans, and visual-motor coordination difficulties. It is especially high in those babies whose heads are relatively small at birth. Genetic defects and infections occurring before birth are uniformly associated with neurologic abnormalities. In other cases, a good birth experience and a correctable cause of growth restriction usually gives a better outcome, if the baby is kept warm, fed correctly and monitored properly.
Long-term, these babies seem to develop an abnormal cell programming of the endocrine system and other body metabolic regulators during their time of deprivation in the womb. This predisposes them to adult diseases such as hypertension, coronary disease and hypercholesterolemia, and diabetes mellitus.
Reviewed by Afsaneh Khetrapal Bsc (Hons)