[Longer oral contraception history as a possible preventive factor against fetal trisomy 21 in advanced maternal age pregnancies]. / A terhességet megelozoen alkalmazott hosszabb távú orális fogamzásgátlás mint a magzati 21-es triszómia lehetséges kockázatcsökkento tényezoje idos anyai életkorban vállalt terhességben.

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. Despite intensive research, pathophysiology of this genetic disorder is not fully understood. According to recent studies, a different kind of mechanism may be found in the background of trisomy 21 than was previously considered. Based on the ovarian mosaicism model, the cause of trisomy 21 (or any common trisomy) is a segregation error of a chromosome in premeiotic mitosis. The cell entering meiosis will be an oocyte with preexisting trisomy, where its (so-called "secondary") nondisjunction is essential. Maturation of the trisomic oocytes appears to fall behind the disomic oocytes, resulting in their relative accumulation in the ovaries as time progresses. The ratio of trisomic/disomic cells becomes less favorable in maternal maturity. If ovulation is inhibited - although the number of oocytes will continue to decline due to apoptosis - it can be assumed that the trisomic/disomic oocyte ratio remains more favorable with the progression of age. In our summary report, presenting and updating our previous data, we would like to propose that - according to ovarian mosaicism model - long-term oral contraception in the anamnesis may be beneficial in pregnancies with advanced maternal age. Orv Hetil. 2018; 159(28): 1146-1152.

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. Medical record details were confirmed through telephone interviews with patients; the estimated ovulation number was calculated and compared among patients, as were factors contributing to the number of ovulations each patient had. RESULTS: Data from 12 776 genetic counseling situations were examined; 35 patients with fetal trisomies and 100 patients in the control group were interviewed. Shorter mean length of oral contraceptive pill use before trisomic pregnancy (P<0.001) and a higher estimated ovulation number (P=0.012) were identified among patients with pregnancies with fetal trisomies. CONCLUSION: Fewer ovulatory cycles, potentially resulting from longer oral contraceptive pill use, was associated with healthy fetal karyotypes among patients of advanced reproductive age.

[Next generation sequencing and its applications in non-invasive prenatal testing of aneuploidies]. / Új generációs szekvenálás és használata az aneuploidiák nem invazív praenatalis vizsgálatában.

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. After discussing the theoretical and technical background, the authors review current application and utility of non-invasive prenatal testing. They conclude that non-invasive prenatal testing is the most effective screening test in high risk pregnancies and its efficiency can be justified in studies involving low risk pregnancies as well.