Second-trimester maternal serum screening for Down syndrome in in vitro fertilization pregnancies.

To examine whether second-trimester maternal serum triple marker screening results differ between in vitro fertilization (IVF) pregnancies and naturally conceived pregnancies. Second-trimester maternal serum triple marker screening results from 88 IVF pregnancies were compared with 596 naturally conceived pregnancies (controls). Controls were matched to each IVF pregnancy by maternal age, gestational age and date of blood collection. All pregnancies in the study were known to have normal outcome. Multiple of the median (MoM) levels of human chorionic gonadotrophin (hCG), unconjugated estriol (uE3) and alpha-fetoprotein (AFP), and the false-positive rate for Down syndrome were compared between the two groups. No statistically significant differences in analyte levels or in Down syndrome false-positive rate were observed between the IVF and naturally conceived pregnancies. IVF patients can be counselled about maternal serum triple marker screening in the same manner as patients with naturally conceived pregnancies. There is no evidence to support the general use of analyte correction factors in the interpretation of second-trimester maternal serum screen results in IVF pregnancies.

Rice JD ，McIntosh SF ，Halstead AC 《PRENATAL DIAGNOSIS》

Serum triple-marker screening in in vitro fertilization and naturally conceived pregnancies.

Frishman GN ，Canick JA ，Hogan JW ，Hackett RJ ，Kellner LH ，Saller DN Jr ... -  《OBSTETRICS AND GYNECOLOGY》

Cell-free fetal DNA levels in pregnancies conceived by IVF.

Pan PD ，Peter I ，Lambert-Messerlian GM ，Canick JA ，Bianchi DW ，Johnson KL ... -  《HUMAN REPRODUCTION》

Preliminary evidence for associations between second-trimester human chorionic gonadotropin and unconjugated oestriol levels with pregnancy outcome in Down syndrome pregnancies.

Benn PA 《PRENATAL DIAGNOSIS》

Triploidy identified through second-trimester serum screening.

To describe the maternal serum marker patterns of triploid pregnancies and estimate the second-trimester prevalence of triploidy. Forty-two cases of triploidy were identified in six serum screening programmes, five in the United Kingdom, one in Canada. This study describes the serum marker patterns, serum screening results for Down syndrome, trisomy 18 and open neural tube defects, and maternal age of these triploidy cases. The risk cut-off levels were > or = 1 in 250 for Down syndrome, > or =2.5 MoMs alpha-fetoprotein for open neural tube defects and > or =1:100 for trisomy 18 screening. The estimated second-trimester prevalence of triploidy was based on 22 triploidy cases ascertained in 599 934 pregnancies from three routine screening programmes, which attempted complete ascertainment of aneuploidy cases. The observed second-trimester rate of triploidy was 0.37 per 10 000 fetuses. Two different serum marker patterns were seen in triploid pregnancies, distinguished from each other by typically very high or very low levels of total hCG or free beta-hCG. The median maternal ages were respectively 33 years for triploidy with human chorionic gonadotrophin levels < 1.0 MoM, and 26 years for those with hCG levels > or =1.0 MoM. Fifty-seven percent of the pregnancies with a triploid fetus had a risk estimate > or =1:100 for trisomy 18 alone, 10% had an alpha-fetoprotein > or =2.5 MoM, 5% were screen positive for Down syndrome alone, and 19% had an increased risk or positive results for more than one anomaly. The simultaneous use of maternal serum tests designed to screen prenatally for Down syndrome, neural tube defects, and an increased risk of trisomy 18 resulted in a screen-positive result for 90% of pregnancies with triploidy.

Huang T ，Alberman E ，Wald N ，Summers AM ... -  《PRENATAL DIAGNOSIS》