Surfactant abnormality and the sudden infant death syndrome - a primary or secondary phenomenon?

Article Abstract:

Sudden infant death syndrome (SIDS) is the most common cause of death during the first year of life, yet its cause remains uncertain. One theory which seeks to explain SIDS is that the fatty surfactant (or detergent) which lines the lungs may be abnormal in these infants and similar to that observed in premature babies with respiratory distress syndrome (RDS). However, not all the changes in the lung surfactant of SIDS babies resemble those seen in RDS babies; rather than being the cause of SIDS, the changes in lung surfactant may be a secondary phenomenon. To determine whether the changes in lung surfactant are primary or secondary in cases of SIDS, the incidence of surfactant abnormalities and SIDS were studied during autopsy. Deaths were classified as SIDS (unexpected death with no explanation or cause), SIDS plus (additional findings which might explain illness, but insufficient to cause death), or non-SIDS (sufficient medical features to completely explain the infant's death). Infants in the SIDS and SIDS plus groups were about equally divided between ages below and above 14 weeks, while almost all non-SIDS infants were above 14 weeks of age. Surfactant composition reflected autopsy findings and not age groups. There are three types of phospholipids (a kind of fat) in lung surfactant, and one type, phosphatidylcholine, was deficient in the lungs of the SIDS groups. In addition, phosphatidylcholine from the SIDS groups contained less of one fatty acid (palmitic acid) in its structure than the phosphatidylcholine from the non-SIDS group. Usually, surfactant from RDS infants is deficient in all three types of phospholipids. Pathogenic (disease-causing) bacteria were isolated from only a few lungs of each group, and surfactant levels were higher in these cases. Other bacteria were isolated, primarily from the SIDS groups. These bacteria are known to be have phospholipase A2 activity, in which phospholipids are broken down. However, the surfactant composition did not completely reflect the expected breakdown products, and bacterial correlation with SIDS was not significant. Because no other evidence linking SIDS with primary or secondary surfactant changes is provided by the data, further research is recommended to explore this finding. (Consumer Summary produced by Reliance Medical Information, Inc.)

Analysis, Causes of, Sudden infant death syndrome, Pulmonary surfactant, Pulmonary surfactants

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Diagnosis and management of fetal growth retardation

Article Abstract:

Fetal growth retardation (FGR) is defined as the failure of the fetus to grow to its fullest potential and is characterized by low birth weight and small size for the gestational age. Methods for preventing FGR and identifying women at risk for FGR, specific treatments, and delivery of growth-retarded infants are discussed. Factors that increase the risk of FGR include alcohol consumption in pregnancy, poor nutrition, maternal smoking, and maternal medical conditions such as heart disease, kidney disease, and preeclampsia (elevated blood pressure, fluid retention and protein in the urine). Different ways to improve fetal growth include giving up smoking and stopping, or at least reducing, alcohol consumption. In addition, researchers are investigating whether low doses of aspirin may help prevent FGR in pregnancies that are at risk for it. The best method for identifying FGR is by measurements taken of the baby's dimensions during ultrasound scans. When FGR is evident, counselling is recommended. Maternal awareness of fetal movement and monitoring of the fetal heart rate are reliable methods used to evaluate whether the fetus is in good health. Specific treatments, such as nutritional supplementation, maternal hyperoxygenation, and improving uterine blood flow, need further evaluation. Delivery of a fetus with FGR depends upon the individual case, but the standard procedure is to deliver once the head and bone measurements become inconsistent or when 37 weeks of gestation is reached, whichever is sooner. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Reports, Complications and side effects, Pregnant women, Fetal growth retardation, Pregnancy, Fetal alcohol syndrome, Prenatal influences, Malnutrition, Malnutrition in pregnancy

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Behavioural states in normal mature human fetuses

Article Abstract:

The behavior of 80 fetuses was studied by ultrasonography, the use of sound waves to visualize internal structures. Recordings were taken between 36 and 42 weeks' gestation; approximately 40 weeks' gestation is considered full-term. Movements of the eye, body movements, and heart rate patterns were found to be interrelated, and three different behavioral states could be identified. During quiescence (the period of inactivity), referred to as state 1F, there were no fetal eye or body movements with the exception of an occasional startle, and the heart rate pattern was consistent. The remaining two states were considered active. State 2F was associated with continuous eye movements, frequent bursts of body movements, and wide variations in heart rate, with increases in heart rate associated with movement. State 4F was characterized by continuous eye and body movements, and a persistent tachycardia (rapid heart rate). These observations were consistent with criteria for three of four previously reported behavior states of the human fetus. Cycling, or transition, between active and quiescent states was observed in 77 fetuses within 100 minutes after the monitoring of fetal activity began. The state known as 2F was the most common behavioral state and was observed 58 percent of the recording time, whereas 1F and 4F were observed 30 and 9 percent of the time, respectively. Behavior could not be classified during 3 percent of the time. (Consumer Summary produced by Reliance Medical Information, Inc.)

Behavior

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