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OBJECTIVE@#To study the influence of maternal sex chromosomal abnormalities on the prediction of fetal sex chromosome abnormalities (SCAs) by non-invasive prenatal testing (NIPT).@*METHODS@#Thirty-six pregnant women with a prediction for fetal SCAs by NIPT were verified as false positive after prenatal diagnosis using amniotic fluid samples. With informed consent, these women were subjected to chromosomal karyotyping or copy number variations (CNVs) analysis through high-throughput sequencing.@*RESULTS@#Sex chromosomal abnormalities were found in 8 women, which yielded an abnormal rate of 22.22% (8/36). Among these, 3 had sex chromosome aneuploidies (47, XXX), 4 had sex chromosome mosaicisms, and 1 carried structural chromosomal abnormalities. Reanalysis of the results of NIPT were consistent with the maternal CNVs by large. With the ratio of cffDNA (ChrX)/cffDNA was more than 2, 6 of the eight women were found to harbor sex chromosome abnormalities, and the fetal karyotype was normal. However, with a ratio of less than 2, only 2 of the 38 pregnant women had sex chromosome abnormalities, and 10 of the fetuses were confirmed as positive.@*CONCLUSION@#The presence of maternal sex chromosomal abnormalities can greatly influence the result of NIPT, which may also be an important reason for false prediction for fetal SCAs by NIPT. When NIPT indicates abnormal SCAs, it is necessary to analyze maternal sex chromosomes. The ratio of cffDNA(ChrX)/cffDNA may help to determine the source of abnormal signals.
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Objective To explore the changes in gravida's age and its influences on maternal and neonatal complications under China's two-child policy.Methods This study retrospectively analyzed the clinical data such as adverse gestational complications and fetal condition of 42 771 gravidas delivering at Changzhou Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University from July 2013 to December 2017.According to their age at delivery,they were divided into three groups:the younger maternal age group (1 140 cases,＜20 years),the advanced maternal age group (4 307 cases,≥ 35 years) and the median maternal age group (37 324 cases,≥ 20 and ＜35 years).Chi-square test was used to compare the differences among groups.Cochran-Armitage test was used for trend analysis.The risks of various complications in younger and advanced maternal age groups were analyzed by binary logistic regression analysis.Results (1) The proportion of advanced maternal age pregnancies tended to rise gradually year by year (Z=-9.909,P＜0.001).However,the figure of younger gravidas remained low and presented a downward trend (Z=10.685,P＜0.001).(2) The incidence of pregnant complications in the younger,advanced and the median maternal age groups were 52.8％ (602/1 140),72.3％ (3 116/4 307) and 56.5％ (21 091/37 324),respectively.Compared with the median maternal age group,the advanced maternal age group was at greater risks of premature delivery [9.0％ (3 343/37 324) vs 11.6％ (499/4 307),x2=124.233,P＜0.001],fetal growth restriction (FGR) [0.6％ (218/37 324) vs 1.2％ (50/4 307),x2=20.087,P＜0.001],postpartum hemorrhage [5.7％ (2 120/37 324) vs 7.8％ (336/4 307),x2=31.299,P＜0.05],hypertensive disorders in pregnancy(HDP) [4.2％ (1 561/37 324) vs 8.7％ (376/4 307),x2=180.013,P＜0.001],gestational diabetes mellitus (GDM) [7.6％ (2 845/37 324) vs 15.1％ (650/4 307),x2=280.126,P＜0.001]and placenta previa [1.7％ (621/37 324) vs 3.8％ (165/4 307),x2=97.904,P＜0.001],and the younger maternal age group was at greater risks of HDP [4.2％ (1 561/37 324) vs 5.9％ (67/1 140),x2=4.234,P=0.040],fetal distress [3.5％ (1 325/37 324) vs 5.1％ (58/1 140),x2=7.546,P=0.006],premature delivery [9.0％ (3 343/37 324) vs 15.0％ (171/1 140),22=48.668,P＜0.001] and FGR [0.6％ (218/37 324) vs 1.1％ (12/1 140),x2=4.086,P=0.043].(3) Gestational complications in the younger maternal age group were mainly related to the fetuses such as premature rupture of membranes (PROM) and premature delivery,while the advanced maternal age group had a higher incidence of maternal complications,especially GDM and HDP.(4) Most of the gravidas of advanced maternal age with HDP developed severe preeclampsia (47.9％,180/376),while mild preeclampsia was dominant in the median maternal aged HDP women (45.4％,708/1 561).(5) The advanced maternal age group had higher risk of stillbirth,premature delivery,FGR,placenta previa,GDM,HDP and postpartum hemorrhage [OR(95％CI):1.91 (1.29-2.84),1.33 (1.21-1.46),1.66 (1.21-2.28),2.56 (2.15-3.04),2.39 (2.19-2.61),2.36 (2.11-2.65),1.46 (1.31-1.62);all P＜0.05],but lower risks of fetal distress and PROM [OR(95％CI):0.79 (0.65-0.95) and 0.88 (0.81-0.96);both P＜0.05].The younger maternal age group had a higher risk of premature delivery [OR(95％CI):1.97 (1.61-2.40);P＜0.001],but significant lower risks of PROM and GDM [OR(95％CI):0.77 (0.62-0.95) and 0.05 (0.02-0.16);both P＜0.05].Conclusions Maternal age is closely related to the adverse outcomes of pregnancy.Two-child policy in China will bring about changes in maternal age and composition of pregnant complications.
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<p><b>OBJECTIVE</b>To explore the cause of failure of non-invasive prenatal testing (NIPT) using cell-free fetal DNA from peripheral maternal blood.</p><p><b>METHODS</b>A total of 31 832 cases of NIPT were retrospectively analyzed. The clinical data of pregnant women were analyzed and the outcome of pregnancy was followed up.</p><p><b>RESULTS</b>Among the 31 832 cases, 200 patients have failed for the first NIPT test. Second test has succeeded in 171 (85.9%) of 199 cases, while 28 cases (14.1%) still yielded no effective results. This gave rise for a total failure rate of 0.088%. Of the 28 cases, 11 (39.2%) were due to high content of total free DNA and could not be sequenced, 17 (60.7%) were found to have the fetal DNA content of less than 4%. Among the 171 cases which have obtained a valid result, NIPT showed that there were 4 patients with high risk of trisomy 21, 18 cases with high risk of 18 trisomy and 1 case with high risk of 13 trisomy. Karyotyping analysis of the amniocytic chromosomes has identified 3 cases with 47,XN,+21, 1 case with 46,XN,rob(21;21), 1 case with 47,XN,+18, while the 13 trisomy case was found to be false positive. For the 28 cases with failed NIPT retest, 14 had normal delivery, with no anomaly noticed in the neonates. Nine patients had opted for artificial abortion during middle or late pregnancy due to maternal factors (4 cases) or fetal factors (5 cases). Four patients developed complications of pregnancy. One case was in good condition upon follow-up. Four cases were lost during follow-up. Of the 11 pregnant women who had failed the NIPT test due to high content of total free DNA, 6 (54.5%) had opted for artificial abortion during midterm pregnancy, which was significantly higher than that of pregnant women with low free DNA content (17.6%).</p><p><b>CONCLUSION</b>Failure of NIPT testing should attract attention from researchers. Failure of single NIPT test should not be regarded as a high risk signal for fetal chromosomal aneuploidies. For those where the test has failed again, genetic counseling and strengthened perinatal care should be provided for the pregnant women.</p>
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OBJECTIVE To assess the performance of non-invasive prenatal testing (NIPT) based on massive parallel sequencing. METHODS A total of 10 275 maternal blood samples were collected. Fetal chromosomal aneuploides were subjected to low coverage whole genome sequencing. Patients with high risks received further prenatal diagnosis. The outcome of all patients were followed up. RESULTS High-throughput sequencing detected 72 pregnancies with fetal autosomal chromosomal aneuploidy, including 57 cases of trisomy 21, 14 cases of trisomy 18, and 1 case of trisomy 13. The positive predictive value for trisomies 21 and 18 were 98.25% and 91.67%, respectively. Comparing its performance in intermediate or high risk pregnancies, advanced maternal age pregnancies and volunteering to test pregnancies, the positive predictive value were 100%, 95%, 90% and 50%, respectively. The follow up result was only 1 case of 21 trisomy false negative with high risk. For the 56 cases of trisomy 21, the high risk group accounted for 55%, advanced maternal age accounted for 29%, the intermediate risk referred to 14%, the volunteering to test group accounted for 2%. CONCLUSION The performance of NIPT for trisomies 21, 18 and 13 was satisfactory. The method can be used for women with advanced gestational age. NIPT has offered an ideal secondary screening method for those with an intermediate or high risk, and can reduce the rate of birth defects.