Amniotic fluid karyotyping analysis of 6584 women of advanced maternal age at second trimester / 中华围产医学杂志

ABSTRACT

Objective To calculate the incidence of chromosomal abnormalities at second trimester in women who were 35 or older at their expected date of birth.Methods The amniocentesis and karyotyping results in Peking Union Medical College Hospital from January 1st,2001 to June 30th,2011 were retrospectively analyzed.The only indication for amniocentesis in these group of woman was advanced maternal age.A total of 6584 cases Were included in this study and were divided into two groups according to maternal age,ie.35-39 and ≥40 year old group.The incidences of fetal 47,+ 21,47,+ 18 and sex aneuploidies were calculated and compared between two groups by Chi-square test.Results Altogether,121 cases were diagnosed to be abnormal chromosome,and the overall incidence was 18.38‰ (121/6584).The abnormal karyotypes included 111 cases of aneuploidies (mosaicism included) and 10 cases of structural abnormalities.The aneuploidies included 59 cases of 47,+21 (8.96‰,59/6584),25 cases of 47,+18 (3.80‰,25/6584),2 cases of 47,+13 (0.30‰,2/6584) and 25 cases of sex aneuploidies (3.80‰,25/6584).Fetal 47,+21 was the most frequent chromosomal abnormality,accounting for 53.15％ (59/111) of all aneuploidies.The incidence of fetal 47,+21 was significantly higher in ≥40 year-old group than that of 35-39 year old group[13.99‰(16/1144) vs 7.90‰(43/5440),x2=3.937,P=0.047].There were no statistical differences of the incidences of fetal 47,+ 18 and sex aneuploidies between the two groups.Conclusions The main fetal chromosomal abnormalities in women aged 35 and older are the aneuploidies of chromosome 21,18,13 and sex chromosomes.The incidence of fetal 47,+21 is significantly increased in the women aged 40 years and older.So prenatal screening should be provided first to women at 35-39 years of age and amniocentesis should be the first choice of prenatal diagnosis for women over 40 years old.