IUGR (Intra-uterine growth retardation)
IUGR may occur when there is a reduction in the function of the placenta. lf the placental cells do not attach appropriately to the mother’s uterus and implant deeply in her blood vessels in early pregnancy then placental function may be reduced. This may lead to placental insufficiency with a reduction in the volume of mother’s blood flowing to the placenta to provide nutrients and oxygen for the baby. The cause is often unknown but it may be related to the mothers nutrition and smoking, increased blood clotting (thrombophilia), hypertension and pre-eclampsia or a twin pregnancy. As the flow decreases the baby’s brain and head continue to grow while the other organs slow down, a phenomenon called the brain sparing effect. These babies have fewer fat stores and a smaller abdomen because there is less glycogen and sugar available to be stored in the baby’s liver. Severe placental insufficiency beginning in early pregnancy may not be associated with “brain sparing” and the babies remain symmetrical and small IUGR babies are prone to fetal distress in labour and hypoglycaemia (low blood sugar) after birth because the sugar reserves are low. lf labour is normal and feeding begins at birth less severely affected babies’ weight may catch up within a few months.
A number of abnormalities apart from the placenta may reduce the baby’s growth including infections (Rubella, Toxoplasmosis, Syphilis) and drug abuse {cigarettes, alcohol and heroin). Congenital abnormalities including Down’s Syndrome and other chromosomal abnormalities and heart or skeletal anomalies may also lead to a low birth weight. Antenatal ultrasound scans and tests usually provide a diagnosis before the birth and these babies usually do not show the brain sparing effect. Some of them may have a long-term disability.