Urinary hyperglycosylated hCG in first trimester screening for chromosomal abnormalities.

Hyperglycosylated human chorionic gonadotrophin (H-hCG), also known as Invasive Trophoblast Antigen or ITA, is a unique metabolic variant of hCG with more complex oligosaccharide side chains. Concentrations are independent of regular hCG. Urine H-hCG has recently proved to be a highly sensitive marker for Down syndrome screening in the second trimester of pregnancy. We evaluated H-hCG as a potential marker in the first trimester of pregnancy. Maternal urine samples were collected from 10(+0) to 11(+6) weeks of gestation prior to genetic analysis and stored in frozen form. Samples from eight cases of Down syndrome, two cases of trisomy 13, one case of trisomy 18, and 55 control pregnancies were hand-carried frozen to the USA and tested blindly. Samples were tested in a specific H-hCG immunoassay and values were normalized to creatinine concentration. Values were plotted against gestational age, and multiples of control pregnancy median (MoM) calculated. The median level of the MoMs of the eight Down syndrome cases was 3.6 MoM. Five of the eight Down syndrome cases exceeded the 90th centile of the 55 unaffected cases. The MoMs of the trisomy 13 and 18 pregnancies were 0.2, 0.2 and 0.3. All three cases were under the 10th centile of unaffected pregnancies. The results of this study indicate that H-hCG testing may be useful in screening for Down syndrome in the first trimester of pregnancy. Further studies are needed to assess the potential screening values of urine H-hCG and the combination of this test with free beta-subunit, PAPP-A and other markers for Down syndrome in the first trimester of pregnancy.

First-trimester maternal serum human thyroid-stimulating hormone in chromosomally normal and Down syndrome pregnancies.

Maternal serum human thyroid-stimulating hormone (TSH) levels were investigated in chromosomally normal and Down syndrome pregnancies to determine whether TSH can be used as a marker for Down syndrome in the first trimester. Measurements were conducted on stored serum samples collected from 23 Down syndrome pregnancies and 115 unaffected pregnancies before chorionic villus sampling (CVS), between 9 and 11 completed weeks of pregnancy. The samples were matched for gestational age, maternal age, maternal weight and duration of storage of the serum sample. Maternal TSH concentration was slightly decreased in Down syndrome pregnancies, with a median of 0.84 multiples of the median (MoM). Maternal serum human chorionic gonadotropin (hCG) concentration was slightly elevated in Down syndrome pregnancies, with a median of 1.03 MoM. Both differences were not significant applying matched rank analysis (p=0.50 for TSH and p=0.43 for hCG). The association between TSH and hCG in unaffected pregnancies was also measured. The Spearman correlation coefficient between TSH and hCG was -0.21 which was statistically significant (p=0.02, 95% confidence interval -0.38 to -0.03). However, it was concluded that TSH is not a useful marker for distinguishing Down syndrome-affected pregnancies from normal pregnancies in the first trimester.

How women deal with the results of serum screening for Down syndrome in the second trimester of pregnancy.

To gain insight into how pregnant women experience serum screening for Down syndrome, we sent questionnaires to two groups of relevant subjects in the north of the Netherlands. The questionnaires addressed the following issues: decision-making process, knowledge and opinions. Questionnaire A was sent to women of 36 years of age and older (n=99) (group A) who were all 20 to 36 weeks pregnant at that time. In the Netherlands prenatal diagnosis is routinely available to these women. Questionnaire B was sent to women of younger than 36 years (n=69) (group B) who had received a screen-positive result and had subsequently undergone amniocentesis. About half of these women were still pregnant at that time. For these women, serum screening is only available on the basis of opting-in. The two questionnaires were largely identical. The response rates to questionnaires A and B were 82% and 91%, respectively. Group A (women of 36 years and older) considered that second trimester serum screening made a welcome contribution to the decision-making process about whether to undergo amniocentesis. Moreover, it reduced the amniocentesis rate considerably. The vast majority said they would apply for serum screening in a following pregnancy, but favoured the idea of first trimester screening. In group B (women of younger than 36 years), reassurance was the most commonly mentioned reason for undergoing serum screening. Almost all the women experienced some degree of anxiety when they were informed about the screen-positive result and 13% continued to be anxious, even after the favourable result of the amniocentesis. The majority of the respondents would also apply for serum screening in a following pregnancy and were of the opinion that this screening should be offered to all pregnant women in the Netherlands.