Down Syndrome and Seasonality Effects Based on Last Menstrual Period

Background:In all population the prevalence of trisomy of 21 has been shown related to maternal childbearing age. Down syndrome is one of the most common etiology of mental impairment among live born children .It may be seasonal relationship with prevalence of trisomy of 21.Many studies based on hormonal variation in human brains in different months of year and few studies by attention to air pollution in seasonal pattern had different result .Method & material: Our study was a retrospective study from 2010 until 2017 among prenatal screening consults that were referred to our center .All of them were 685 pregnant women that were consulted about high risk screen tests or abnormality in first or second trimester sonography or high risk cell free DNA test .After diagnostic tests were done, (CVS or amniocentesis ),We classified abnormal karyotypes based on maternal age ,the month of conception based on the last menstrual period or month of egg transferring in cases of IVF.Result: For 685 mother, diagnostic tests were done and n= 35 cases (5.1%) had abnormal karyotype ,the distribution was XO n=4,(0.58%),trisomy13 n=4,(0.58%), trisomy 18 n=4,( 0.58%) ,trisomy 21,n=18 (2.62%), chromosomal structural abnormality n=5,( 0.72%). Based on the month of conception , n = 18 (2.62%) related to autumn and n=12,(1.75% ), about winter , and n=5(0.72%) for spring and summer. Among 685 cases 358 had ,IVF,101 ovulation induction,226 spontaneous pregnancy that had 18(2.62%) ,11(1.60%),6(0.87%) abnormal karyotype respectively.Conclusion: aneuploidy may be related to the time of conception in order to air pollutant or hormonal changes in human and so on .sub fertility and ART may affect on aneuploidy prevalence too. And both need large studies.

کلیدواژه ها:

trisomy –seasonal-prevalence