Influence of smoking habits on Down's syndrome risk evaluation at mid-trimester through biochemical screening.

Expectant mothers who smoke have higher levels of maternal serum alpha-fetoprotein and lower levels of unconjugated estriol and total human chorionic gonadotrophin than non-smoking mothers. This significantly affects performance of screening for Down's syndrome. This study includes 22,169 pregnant women: 18,876 non-smokers, 2,660 smoking < or = 10 cigarettes/day, and 633 smoking > 10 cigarettes/day. Mean maternal age (32.6 years), maternal weight (60.5 kg), and gestational age (114.7 days) were similar or only slightly different between the three groups. To verify the effects of smoking on screening, we studied retrospectively 130 sequential Down's syndrome cases (47 from the screening program, 83 from the prenatal diagnosis program). The proportion of smokers in the Down's syndrome and unaffected pregnancies was similar, whilst the false-positive rate and detection rate, based on fetal outcome, differed: false-positive rates were 5.63% in smokers and 9.42% in non-smokers, and detection rate 55.6% in smokers and 83.0% in non-smokers. Since the prevalence of Down's syndrome pregnancies was the same at mid-trimester in smokers and non-smokers and the proportion of smokers was not related to maternal age, we propose an adjustment of the Down's syndrome risk evaluation algorithm according to smoking habits.

Repeat testing of mothers with high human chorionic gonadotrophin levels in Down's syndrome screening.

Multiples of medians of serum markers are assumed to be independent of gestational age: every algorithm used for Down's syndrome risk evaluation is based on this hypothesis. However, our former observations suggested that multiples of medians of human chorionic gonadotrophin in Down's syndrome are dependent on gestatational age. Furthermore, observations on 84 Down's syndrome cases confirmed that human chorionic gonadotrophin multiples of medians in samples drawn at 15-17 weeks are approximately 10% lower than in samples drawn at 18-21 weeks, thus showing that the human chorionic gonadotrophin concentration decreases about 10% less than expected. The control group comprised 554 women with two blood samples and normal human chorionic gonadotrophin at first sampling. A further group of 532 women with multiples of medians at first sampling > 1.8 was examined with the aim of excluding an association between the human chorionic gonadotrophin trend in Down's syndrome and high starting values. The trend is peculiar to human chorionic gonadotrophin in Down's syndrome pregnancies and may help to explain the increase in detection rate with gestational age. Based on these findings, screening can be optimized, thus improving performance.

Maternal serum markers. Estimation of the risk of Down's syndrome: a prospective study.

The risk of Down's syndrome pregnancies can be estimated by quantitation of maternal serum markers, namely alpha-fetoprotein, unconjugated estriol and human chorionic gonadotropin (triple test). A prospective study of 2892 pregnant women (median age 33.5 years) is reported. The detection rate of Down's syndrome pregnancies was 80% (confidence intervals 45%-100%) when a risk of 1:380 or greater was considered "screen positive", the false positive rate was 13.3% (confidence intervals 12.0%-14.5%). The importance of the accurate assessment of gestational age and the time of blood sampling are emphasized. Our findings are compared with similar studies performed in other laboratories.

[Variations in ferritin levels in blood during physiological pregnancy]. / Variazione dei livelli di ferritinemia nella gravidanza fisiologica.

Iron deficiency anemia is the most frequent haematological pathology in pregnancy. Serum ferritin levels represent the state of iron deposits. Low levels are a sure sign of iron deficiency. At the University of Turin we studied the variations of serum ferritin levels during physiological pregnancy and the sensitivity of routine blood tests with respect to serum ferritin levels. Routine haematological blood values along with ferritin levels were measured in 115 patients throughout pregnancy. The mean serum ferritin level was 56 ng/ml in the first trimester, 27.2 ng/ml in the second and 11.8 ng/ml in the third. The incidences of anemia per trimester was 6.6%, 4.8% and 49% respectively (p less than 0.05, chi squared). Our results show that it is important to evaluate iron deposits early in pregnancy by measuring serum ferritin levels in order to determine the need for iron therapy.

Screening for fetal Down's syndrome with maternal serum markers--an experience in Italy.

The effectiveness of maternal serum alpha-fetoprotein, unconjugated oestriol, and human chorionic gonadotrophin in screening for Down's syndrome (DS) was evaluated on 840 women who underwent amniocentesis for fetal karyotype on account of their age. The risk of a DS pregnancy was established using the method of Wald et al. (1988b), which combines the age-specific risk with that indicated by the levels of the three serum markers. In women over 35, at cut-off risk levels of 1:250 and 1:380, the false-positive rate was 24 and 34 per cent, respectively. In all nine cases of DS, the estimated risk was higher than 1:250. The best screening strategy with the lowest false-positive rate was obtained by combining the three serum markers. The results suggest that this kind of screening can be proposed during genetic counselling for women under 35 and older women wishing to avoid the risk of miscarriage induced by amniocentesis.