Abstract
BackgroundTo determine whether advanced maternal age (AMA) causes changes in the maternal serum markers of Trisomy 21, 18 and open neural tube defects (ONTD) during the second trimester of pregnancy. Our research aims to develop new cut-off values for AMA in order to reduce the need for further invasive testing.MethodsThis retrospective cohort study involved 12,739 pregnant women with AMA and 197,101 pregnant women with non-AMA. We then compared the two groups with respect to the positive rate and positive predictive value (PPV) of Trisomy 21, 18 and ONTD. Pregnant women with Trisomy 21, 18 and ONTD were diagnosed by karyotyping the amniotic fluid and by ultrasound diagnosis.ResultsCompared to the non-AMA group, the multiple of the median (MOM) of free beta- human chorionic gonadotropin (free β-hCG), alpha-fetoprotein (AFP), and the risk value forTrisomy 21, were significantly higher in the AMA group (all P < 0.001). The positive rates of Trisomy 21, 18, and ONTD in the AMA group were significantly higher than those in the control group (all P < 0.001). In the AMA group, the PPVs for Trisomy 21 and other deformities were significantly higher (all P < 0.001), although the PPVs for Trisomy 18 and ONTD were similar to those of the non-AMA group. The area under the curve (AUC) values for the AMA group were higher than the non-AMA group, based on free β-hCG MoM, AFP MoM, and the risk value of Trisomy 21. The cut-off value for the risk value of Trisomy 21 was 1/172 for the AMA, group and 1/780 for the non-AMA group.ConclusionsThe positive rates for Trisomy 21, 18 and ONTD, and the PPV for Trisomy 21 and other deformities were significantly higher in the AMA group. It is essential for pregnant women with AMA to be tested using appropriate cut-off values of serum markers screening for Trisomy 21 during the second trimester of pregnancy to improve the efficacy of prenatal screening and reduce the need for further invasive testing.
Highlights
To determine whether advanced maternal age (AMA) causes changes in the maternal serum markers of Trisomy 21, 18 and open neural tube defects (ONTD) during the second trimester of pregnancy
Our aim was to investigate the reliability of maternal serum screening for pregnant women with AMA during the second trimester of pregnancy, and to identify new cut-off values for the Trisomy 21, Trisomy 18 and ONTD to reduce the need of amniocentesis
The positive predictive value (PPV) for Trisomy 21 and other deformities were significantly different when compared between the AMA and non-AMA groups (χ2 = 126.245, P < 0.001; χ2 = 50.329, P < 0.001); the PPVs for Trisomy 18 and ONTD were not significantly different
Summary
To determine whether advanced maternal age (AMA) causes changes in the maternal serum markers of Trisomy 21, 18 and open neural tube defects (ONTD) during the second trimester of pregnancy. Trisomy 21, referred to as Down’s Syndrome (DS) or the ‘congenital type’, and trisomy 18, which is known as Edwards’ syndrome (ES), are the most common chromosomal abnormalities, with neonatal incidences of 1/800–1/ 600 [1] and 1/2600–1/2500 [2], respectively. Because these conditions both include additional chromosomal material, Trisomy 21 and 18 are characterized by irreversible mental retardation. Open neural tube defects (ONTD) are considered to be serious congenital birth defects and generally occur before 4 weeks of pregnancy. Previous research showed that ONTD affects 1.2 per 1000 pregnancies worldwide [5]
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