[Longer oral contraception history as a possible preventive factor against fetal trisomy 21 in advanced maternal age pregnancies].

Down syndrome is the most common autosomal chromosomal abnormality. According to the classical interpretation, it is the result of meiotic nondisjunction. Its occurrence is more common in advanced maternal age.

Effect of extended oral contraception use on the prevalence of fetal trisomy 21 in women aged at least 35 years.

Objective: To study factors influencing the number of ovulations in reproductive life as risk factors for common trisomies.

Methods: The present observational study examined data from genetic counseling sessions performed at the 1st Department of Obstetrics and Gynecology, Semmelweis University, Budapest, Hungary, between September 1, 2013, and September 1, 2015, and retrieved data on patients of advanced maternal age (≥35 years) who had fetal trisomy 21, 18, or 13 confirmed. Consecutive patients of advanced maternal age with genetic amniocentesis-confirmed healthy fetal karyotypes were also included as a control group.

[Next generation sequencing and its applications in non-invasive prenatal testing of aneuploidies].

The development of the new generation sequencing techniques brought a new era in the field of DNA sequencing, that also revolutionized the prenatal screening for aneuploidy. In order to provide a more complete view, the authors describe some first generation methods as well as the theoretical and technical background of the next generation methods. In the second part of this review, the authors focuse on non-invasive prenatal testing, which is a fetal cell-free DNA based method requiring advanced sequencing procedures.