{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,17]],"date-time":"2025-11-17T08:06:50Z","timestamp":1763366810569},"reference-count":30,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2005,12,14]],"date-time":"2005-12-14T00:00:00Z","timestamp":1134518400000},"content-version":"vor","delay-in-days":3849,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Prenatal Diagnosis"],"published-print":{"date-parts":[[1995,6]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>The aim of this study was to determine the maternal population, pregnancy, serum alpha\u2010fetoprotein (AFP) and free \u03b2 subunit of human chorionic gonadotrophin (F\u03b2hCG) parameters in a large series of women attending prenatal clinics before 15 weeks' gestation and to assess the practical problems of population screening for Down's syndrome in the first trimester using these markers. Serum samples were collected from 8600 women attending prenatal clinic booking visits. Maternal serum AFP and F\u03b2hCG medians were calculated for each day of gestation (49\u2013104 days), using both dates and ultrasound estimates of gestation. The effects of maternal weight, twin pregnancies, and threatened abortion on AFP and F\u03b2hCG levels were analysed. The median age of the population was 27.1 years and the median weight 62.1 kg. Twenty\u2010six per cent of samples were collected before 70 days and 50 per cent before 78 days' gestation. Eighty\u2010nine per cent of all samples had gestational estimates by dates, 60 per cent by ultrasound and 52 per cent by both dates and ultrasound. The AFP median was 5 kU\/1 at 49 days, 5.9 kU\/1 at 70 days, and 17.9 kU\/1 at 100 days. The peak median F\u03b2hCG level was 66.4 ng\/ml at 64 days, falling to 20.6 ng\/ml at 100 days' gestation. Both AFP and F\u03b2hCG levels showed log Gaussian distributions but the standard deviation for AFP was 20 per cent greater than that found in the second trimester. AFP and F\u03b2hCG levels showed an inverse relationship with maternal weight and were increased in twin pregnancies (1.68 and 1.97 multiples of the median, respectively). AFP and F\u03b2hCG can be readily measured in a large screening population in the first trimester. Down's syndrome screening protocols based on these markers could be refined by the use of gestations in individual days but AFP is likely to be a less effective marker and detection rates are likely to be lower than in the second trimester. To realize the potential of first\u2010trimester screening, more women should be encouraged to attend the prenatal clinic in early pregnancy and ultrasound dating should be carried out for all pregnancies at this stage.<\/jats:p>","DOI":"10.1002\/pd.1970150609","type":"journal-article","created":{"date-parts":[[2007,3,4]],"date-time":"2007-03-04T11:18:31Z","timestamp":1173007111000},"page":"555-565","source":"Crossref","is-referenced-by-count":25,"title":["Analysis of maternal serum alpha\u2010fetoprotein and free beta human chorionic gonadotrophin in the first trimester: Implications for down's syndrome screening"],"prefix":"10.1002","volume":"15","author":[{"given":"Esther","family":"Berry","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"David A.","family":"Aitken","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jennifer A.","family":"Crossley","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"James N.","family":"Macri","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"J.","family":"Michael Connor","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2005,12,14]]},"reference":[{"key":"e_1_2_1_2_1","doi-asserted-by":"publisher","DOI":"10.1002\/pd.1970130804"},{"key":"e_1_2_1_3_1","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(86)91980-X"},{"key":"e_1_2_1_4_1","doi-asserted-by":"publisher","DOI":"10.1111\/j.1471-0528.1993.tb12973.x"},{"key":"e_1_2_1_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/pd.1970100406"},{"key":"e_1_2_1_6_1","first-page":"A270","article-title":"Prenatal screening for Down syndrome using AFP, UE3 and hCG. 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