Preterm birth (birth before week 37 of gestation) occurs in approximately 5-10% of all pregnancies. This value may be higher in certain population groups and has not decreased over the past 20-30 years. Although some preterm births may be elective, approximately 30% occur in association with an underlying infectious process, and about 50% are idiopathic preterm births of unknown cause. Preterm birth is associated with 70% of neonatal deaths, and up to 75% of neonatal morbidity. Infants born preterm have an increased incidence of blindness, deafness, cerebral palsy, neurological disorders and pulmonary disorders (Morrison, 1990;

These results indicate that the magnitude of immunoproliferative responses are unrelated to maternal mite allergen exposure and cannot be used as evidence for in utero sensitization to inhalant allergens. The immunoproliferative responses at 1 year seem to shift away from the genetically influenced responses at birth towards responses to specific stimulants which correlate with environmental exposure to those specific stimulants. These data support the concept of sensitization to inhalant allergens occurring in early life, but not in utero.

The presence of multiple ultrasonographic abnormalities is associated with a significantly increased risk of chromosomal defects, while for isolated abnormalities, the association is less clear. In a study of 1,177 fetuses with mild hydronephrosis at 16-26 weeks of gestation, the fetal karyotype was abnormal in 86 (7.3%) of the cases and the most common chromosomal defects were trisomies 21,18 and 13. The frequency of chromosomal defects increased with the number of additional abnormalities and for each chromosomal defect there was a characteristic pattern of associated abnormalities. However, in the 805 fetuses with apparently isolated hydronephrosis there were 5 (0.62%) with trisomy 21. On the basis of the maternal age and gestational age distribution of the population the expected frequency of trisomy 21 was 0.40%, which was not significantly different from the observed (0.62%). To demonstrate that such a difference is significant, it would be necessary to investigate at least 1 million pregnancies. In the meantime, parents could be counselled that the presence of mild hydronephrosis does not increase significantly the risk that the fetus has trisomy 21. Alternatively, the risk is 1.6 times higher than the maternal age and gestational age-related risk.

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Glucomannan and risk of oesophageal obstruction Glucomannan (glucose/mannose polymer) is considerably hygroscopic and on contact with water swells and becomes a viscous gel. In this form it is a normal Japanese foodstuff. Like guar (galactose/mannose) it has been used to treat diabetes mellitus.' Recently, dry, non-expanded glucomannan has been marketed in Australia as an aid to dieting, the claim being that it inhibits the appetite by swelling in the stomach, producing what one on 4 October 2020 by guest. Protected by copyright.