Cell-free fetal DNA analysis in maternal plasma as screening test for trisomies 21, 18 and 13 in twin pregnancy

OBJECTIVES

To evaluate in twin pregnancy the utility of non-invasive prenatal testing using circulating cell-free fetal DNA (cfDNA) in screening for the three main autosomal fetal trisomies.

METHODS

cfDNA testing was offered to 492 patients with a twin pregnancy without ultrasound anomaly as a first-line screening test or after routine serum screening. Data were collected prospectively and a retrospective analysis was performed. cfDNA analysis was performed by massively parallel sequencing. The fetal-fraction threshold used for test evaluation was 8%. Regression analysis was performed to investigate the effect on the test failure rate of maternal and pregnancy characteristics, and the performance of the test was also reported.

RESULTS

cfDNA analysis was performed as a first-line test (after the first-trimester scan) in 377 patients and following serum screening in 115. Of the 420 pregnancies for which outcome was available and cfDNA screening was assessed, 78.7% were dichorionic-diamniotic. The test failed on the first attempt in 12 (2.9%) pregnancies, and regression analysis demonstrated that only maternal weight was a significant independent predictor of test failure. A result was subsequently achieved in the 10 cases for which a second sample was obtained. cfDNA analysis identified all three cases of trisomy 21 and the only case of trisomy 18. For trisomy 21, the specificity was 99.8% (95% CI, 98.7-100.0%). When considering pregnancies according to whether they were conceived spontaneously or after assisted reproductive technology, there were no significant differences in terms of maternal weight or no-result rate for cfDNA screening between these two groups.

CONCLUSIONS

In twin pregnancy without fetal ultrasound abnormality, cfDNA screening for trisomies 21, 18 and 13 had a high success rate and good performance. Therefore, in routine practice, cfDNA analysis could be considered as a first- or second-line screening test. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

[Cell-free fetal DNA analysis in maternal plasma as a screening test for trisomy 21 in twin pregnancies]

OBJECTIVES

To evaluate the performance of noninvasive prenatal testing by cell-free circulating fetal DNA in maternal blood (cfDNA) in screening for trisomies 21 in twin pregnancies.

METHODS

CfDNA was performed in 492 patients with twin pregnancies without ultrasound anomalies in the first trimester as a first-line screening test or after serum screening. Data were collected prospectively and a retrospective analysis was done. CfDNA was executed by massive parallel technique. The fetal fraction threshold for test evaluation was 8%. Regression analysis was performed to evaluate the effect of different parameters on the test failure rate. Performance of the test was also considered.

RESULTS

In 377 patients, the test was prescribed first line and in 115 after standard serum screening. Twelve tests (2.9%) have initially failed on the 420 pregnancies with available outcomes and regression analysis found only maternal weight as a significant independent factor of test failure. A second test was performed on 10 patients, all of them had an available result. cfDNA identified all 3 cases of trisomy 21. The sensitivity was 100.0% (95% CI [29.2-100.0%]) and specificity was 99.8% (95% CI [98.7-100.0%]). There was no significant difference between spontaneous pregnancies and those induced by assisted reproductive technologies (ART), in terms of fetal fraction percentage, no-call results for cfDNA screening, maternal weight, or test performance between the two groups.

CONCLUSION

In twin pregnancies without fetal ultrasound abnormalities, the performance and success rate of the cfDNA are excellent. Therefore, cfDNA could be offered in routine practice as a first-line screening test in this population.

"Separation" of the mother-child couple: pregnancy and maternity of drug-dependent women

Children of drug addicts are at risk of neglect and scanty maternal care. The objective of the present study was to identify homogeneous subgroups within a sample of drug addicted women, according to the quality of the outcome of the mother-child relationship. A group of 13 opiate-addicted women, followed from the seventh month of pregnancy up until the child was 2 years of age, underwent psychometric evaluation and was subdivided into two distinct groups based on whether the child remained within the family nucleus or was entrusted to a foster family or institution. The psychometric instrument used, an adaptation of Osgood's semantic differential which investigates maternal representations, allowed us to identify items with a very high predictability for the outcome of the mother-child relationship.

[Neonatal abstinence syndrome and maternal toxicological profile]

Neonatal abstinence syndrome (NAS) is one of the most frequent manifestations in the neonates of drug-addicted mothers. It is caused by the abrupt interruption of the transplacentar passage of drugs from the mother to the fetus. The aim of this study was to evaluate the correlation between drugs taken during pregnancy and NAS. Data were examined relating to 223 neonates born during 1975-1992 to drug-addict mothers. Neonates were subdivided into four groups according to the maternal toxicological profile. It was thus possible to observe that there is a greater prevalence of NAS in cases of polypharmacomania and that it gradually diminishes in the children of heroin addicts and those receiving methadone treatment. Moreover, the intensity of the syndrome is correlated to the high doses of methadone and/or heroin. In the group of neonates whose mothers had complied with the methadone treatment protocol, the severity of NAS was proportional to the dose taken by the mother. In conclusion, the management of pregnant drug addicts following a controlled methadone treatment programme is accompanied by improved obstetric help and is the most suitable way of reducing perinatal complications and the prevalence of NAS.