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At least 19 recordsLinked to original sources
PubMed1992

Cytogenetic evidence for enhanced selective miscarriage of trisomy 21 pregnancies with advancing maternal age.

The effect of advancing maternal age on the risk of death of fetuses with certain chromosome abnormalities has been tested by comparing their frequency at the time of chorionic villus sampling (CVS) with that at amniocentesis. The frequency of chromosome abnormalities among women whose sole risk factor for a chromosome abnormality was advanced maternal age (> or = 35 years old) was determined in a pooled group of 15,147 CVS cases, of whom > 1/3 were from the initial 7,500 CVS cases at the University of California, San Francisco, and compared with a pooled group of 74,851 amniocentesis cases collected from the literature. The frequency of trisomy 21 not only increased with advancing maternal age as expected, but the slope of the increase was about 25% greater in the CVS group than in the amniocentesis group (P = 0.08 for the difference in slopes by a logistic statistical model and P = 0.04 by a normit model). Similar patterns were seen for trisomies 18 and 13, but the P values for the differences in slopes were much higher. These results suggest that the miscarriage rate of trisomy 21 during the gestational interval studied is selectively greater with advancing maternal age. The basis for the enhanced selective loss of trisomy 21 with maternal age may be a reduced ability of the ageing "maternal compartment" to compensate for abnormal conceptuses.

Abortion, Spontaneous↗
PubMed2026

Genomic risk profiling in advanced maternal age: a Tamil Nadu prenatal study.

BACKGROUND: Advanced maternal age (AMA; > = 35 years) is associated with increased fetal chromosomal risk and is an important indication for invasive prenatal diagnosis. This study evaluates karyotyping and chromosomal microarray analysis (CMA) findings among AMA pregnancies in Tamil Nadu, India. METHODS: In this prospective observational study, 2,200 pregnant women aged ≥35 years who underwent amniocentesis between July 2020 and June 2021 were enrolled. Conventional karyotyping was performed in all cases. CMA was performed as a reflex or complementary test when predefined clinical or cytogenetic criteria were present, including ultrasound abnormalities, high-risk screening/NIPT results, abnormal or uncertain karyotype findings, prior adverse pregnancy history suggestive of genetic etiology, parental chromosomal abnormalities, or patient request after counseling. RESULTS: Numerical chromosomal abnormalities were detected in 76/2200 cases (3.5%), and structural abnormalities were detected in 9/2200 cases (0.4%). The total abnormal cytogenetic yield was therefore 85/2200 cases (3.9%) when numerical and structural abnormalities were considered together. Age-stratified analysis showed an increasing trend in chromosomal abnormalities with advancing maternal age, reaching 10.4% in women aged > = 43 years. Cases with additional clinical indications showed higher abnormality rates than simple AMA. CMA was performed in selected cases and contributed to characterization of clinically relevant genomic abnormalities, supporting its role in indicated high-risk AMA pregnancies. CONCLUSION: The Tamil Nadu cohort provides regional evidence on age-stratified cytogenetic risk in AMA pregnancies and supports the use of clearly defined criteria for integrating CMA with conventional karyotyping in prenatal diagnosis.

India↗
PubMed1977

An unexpected high frequency of trisomic fetuses in 229 pregnancies monitored for advanced maternal age.

In 229 pregnancies monitored because of advance maternal age, 16 (7%) abnormal fetal karyotypes were detected. We found 13 cases of trisomy 21, twice a trisomy 18, and once an additional marker chromosome. The frequency of abnormal fetal karyotypes in different maternal age groups was found to increase from 1:20 at 38--40 years, to 1:16 at 41--43 years, and finally to 1:4.5 in women of 44--46 years. The overall incidence of chromosomal aberrations and specifically of trisomy 21 is considerably higher than that described in retrospective studies.

Adult↗
PubMed1992

Reproductive behaviour and prenatal diagnosis following genetic termination of pregnancy in women of advanced maternal age.

One hundred and fifty-one women of advanced maternal age who underwent genetic termination of pregnancy (TOP) were studied for their reproductive behaviour and the type of procedure for prenatal diagnosis in a subsequent pregnancy. A total of 59 women (39 per cent) had a further pregnancy. In all continuing pregnancies prenatal diagnosis was performed, of which 75 per cent consisted of chorionic villus sampling (CVS). Reproductive behaviour following a genetic termination was negatively correlated with maternal age and parity. Both reproductive behaviour and the choice to undergo a diagnostic procedure in the next pregnancy were independent of the type of diagnostic procedure in the previous affected pregnancy.

Abortion, Therapeutic↗
PubMed1979

Reducing birth defect risk in advanced maternal age.

The incidence of birth defects increases with maternal age. Recent advances in fetal diagnosis, coupled with elective abortion, offer the older pregnant woman an opportunity to reduce this risk. To determine the magnitude of potential risk reduction, we reviewed the maternal age-specific incidence of infants born with one or more severe birth defects in metropolitan Atlanta from 1968 to 1975, removing from analysis certain anomalies that were preventable by currently available methods. For women aged 35 to 44 years, the risk of bearing an infant with a severe birth defect was reduced to a level comparable with that for younger women. Despite prenatal diagnosis and elective abortion, the risk for women aged 45 years or older, although reduced considerably, was two times greater than that for women aged 34 years or younger.

Adult↗
PubMed1978

[Prenatal diagnosis in pregnancies at advanced maternal age (author's transl)].

Among 113 prenatal diagnoses in pregnancies at advanced maternal age (mothers older than 37 years) 7 aberrant fetal karyotypes were found (6.2%). Detailed reports of one case of trisomy 21, 18 and 13 each, as well as of XXY-, XYY- and XXX gonosomal constitution respectively are presented in the following. The frequency and severity of chromosome aberrations occurring in fetuses from elder women are discussed with respect to data from the literature. It seems that this group bears a higher risk for chromosomally abnormal offspring than has been suggested before.

Abnormalities, Multiple↗
PubMed1992

Maternal height and age: risk factors for cephalopelvic disproportion in Zimbabwe.

Maternal age and stature are among several factors used to screen pregnant women for potential risk of labour complications. In a population-based case-control study in Harare, Zimbabwe, multivariate analysis was carried out to evaluate the importance of maternal age and height as risk factors for cephalopelvic disproportion (CPD). Using data abstracted from the medical records of 203 women with operative deliveries due to CPD and 299 women with normal unassisted vaginal deliveries, multiple logistic regression models were developed. Although maternal age < 18 years was not a significant risk factor in this study (perhaps because there were few women in this age group), advanced maternal age (> or = 35 years) was associated with a relative risk of 2.7 compared to women 20-34, after adjusting for other demographic and obstetric factors. Maternal height < 160 cm was associated with a twofold increased risk of CPD as compared to taller women.

Adolescent↗
PubMed1992

The risk and efficacy of chorionic villus sampling in multiple gestations.

Chorionic villus sampling (CVS) in the first trimester of pregnancy provides a safe and effective method for the early prenatal diagnosis of cytogenetic abnormalities in multiple gestations. In this multicentre study involving 126 twin and 2 triplet gestations primarily at risk because of advanced maternal age, the overall success rate of obtaining an adequate villus sample from each fetus was 99.2 per cent. For women of advanced maternal age, the rate of combined losses of chromosomally normal fetuses due to spontaneous abortion, stillbirths, and neonatal deaths was 5.0 per cent, compared with a 4.0 per cent total loss rate following CVS in singleton pregnancies derived from the same population (Rhoads et al., 1989). There was a 100 per cent success rate in obtaining a cytogenetic analysis; a cytogenetic abnormality was present in five of the multiple gestations (3.9 per cent) and involved seven fetuses (2.7 per cent). There were no diagnostic errors and no cases of normal cytogenetic diagnosis followed by the birth of a cytogenetically abnormal newborn. Based on cases of XX/XY admixture, cell contamination derived either from maternal decidua or the other twin occurred in 6 of 256 samples (2.3 per cent), giving an overall estimate of the frequency of cell contamination of 4.6 per cent; these cases did not present a diagnostic problem. However, there were two cases (0.8 per cent) in which the fetal sex was incorrect, due either to complete maternal cell contamination or to the possibility that in error one twin was sampled twice.

Abortion, Induced↗
PubMed1992

Sonographic scoring index for prenatal detection of chromosomal abnormalities.

Current indications for cytogenetic evaluation leave the majority of Down syndrome fetuses undetected. Using advanced maternal age and low maternal serum alpha-fetoprotein (AFP) levels as criteria, only 40% of fetuses with Down syndrome (trisomy 21) are identified (positive predictive value, 0.4% to 1%). We evaluate the sonographically detectable physical features of second trimester fetuses to determine whether these features are more sensitive and specific than maternal age for detecting fetuses with abnormal karyotypes. From March 1, 1990, to September 1, 1991, more than 5,000 fetuses between 14 and 20 weeks of development were referred for genetic amniocentesis because of advanced maternal age or abnormal AFP levels. Forty-three of these 5,000 fetuses were later found to have autosomal trisomies by karyotype (32 with trisomy 21, nine with trisomy 18, and two with trisomy 13). A sample of 588 consecutive normal fetuses from the total of more than 5,000 amniocenteses performed during this period of time was used as our control group for statistical analysis. The sonographic features of these 588 normal second trimester fetuses and the 43 trisomic fetuses recorded prospectively prior to knowledge of the karyotype were evaluated statistically. The femur and humerus lengths, nuchal fold, renal pelvic dimension, and major structural defects were compared in the normal and trisomic fetuses. On the basis of our results, a weighted sonographic score was developed to optimize the detection of fetuses at risk for aneuploidy. Using our previously published formulas and criteria for a short femur and humerus, 17/32 (53%) fetuses with Down syndrome and 23/588 (3.9%) of the normal fetuses were identified. Twenty two of 32 Down syndrome fetuses (69%) and 2/588 (0.34%) of normals had a nuchal fold > or = 6 mm, and 11 of 32 Down syndrome fetuses and all those with trisomies 18 and 13 had a major anomaly detected sonographically. The following scoring system was developed for the detection of aneuploidy: nuchal fold = 2, major structural defect = 2, and short femur, short humerus, and pyelectasis = 1 each. Selecting fetuses with a score of > or = 2 would identify 26/32 (81%) Down syndrome fetuses, and 9/9 (100%) and 2/2 (100%) fetuses with trisomies 18 and 13 respectively, but only 26/588 (4.4%) of the normal fetuses. Using the sonographic score of 2 results in a positive predictive value for a 1/250 risk group of 6.87% for identifying Down syndrome fetuses and 7.25% for all three trisomies.(ABSTRACT TRUNCATED AT 400 WORDS)

Amniocentesis↗
PubMed1992

[Investigation of the incidence of aberration in various indication for prenatal cytogenetic analysis].

In order to evaluate the role of prenatal cytogenetic analysis for the management of pregnant women, we studied the incidence of chromosomal aberration in 1,258 cases. In 502 cases with advanced maternal age (at least 35 years older), 12 (2.4%) cases of chromosome aberration were detected. The incidence of chromosomal aberration in the cases with women who had a previous child with chromosome aberration, women who had given birth to a congenital malformation child, and women who had ultrasonographic abnormalities were 3.0% (8/271), 0% (0/103) and 11.7% (36/307), respectively. Of cases with advanced maternal age, the incidence of chromosome aberration is 0% (0/21) at age 35, 0% (0/22) at age 36, 19% (1/52) at age 37, 2.2% (2/92) at age 38, 10% (1/102) at age 39, 1.3% (1/75) at age 40, 5.3% (3/56) at age 41, 6.9% (3/43) at age 42, 4.4% (1/23) at age 43 and 6.7% (1/15) at age 44. These results indicate that the incidence of chromosome aberration increases with maternal age. On the basis of these data, we recommend medical practice to offer prenatal diagnosis to all women who will be 37 or older. In the cases of fetal anomaly, they were diagnosed by ultrasonographic examination, the high incidence of chromosome aberration was detected in comparison with another group. Therefore, the prenatal cytogenetical analysis may also be performed in these cases.

Adult↗
PubMed1992

Fetal pyelectasis and Down syndrome: is genetic amniocentesis warranted?

An association between pyelectasis and Down syndrome has recently been reported. The purpose of this investigation was twofold: 1) to test the hypothesis that pyelectasis is more common in fetuses with Down syndrome, and 2) to determine whether genetic amniocentesis should be offered when dilated renal pelves are identified during fetal ultrasound examination. The study population of 5944 fetuses was separated into two groups by infant outcome: 1) phenotypically and/or chromosomally normal, and 2) chromosomally abnormal. Each group was examined for the presence of pyelectasis, defined as an anteroposterior renal pelvic diameter of 4 mm or greater before 33 weeks or 7 mm or greater after 33 weeks. Pyelectasis was observed in 17.4% (four of 23) of Down syndrome fetuses versus only 2% (120 of 5876) of normal controls, a statistically significant difference (P less than .001). The predictive value of pyelectasis for Down syndrome (one in 90) compares favorably with other accepted indications for genetic amniocentesis, such as advanced maternal age and low maternal serum alpha-fetoprotein (MSAFP). When fetuses with concomitant sonographic abnormalities were excluded, the predictive value of isolated pyelectasis fell to one in 340. We conclude that although renal pyelectasis is more common in Down syndrome fetuses, genetic amniocentesis should be reserved for those cases presenting other risk factors such as advanced maternal age, low MSAFP, or other sonographic abnormalities.

Amniocentesis↗
PubMed1975

Intrauterine diagnosis of chromosome anomalies.

Prenatal karyotype analysis was performed on cultured fetal cells obtained by transabdominal amniocentesis at the 15th and 20th week of pregnancy in 63 high risk pregnancies. The reason was advanced maternal age in 42 cases, a previous child with a chromosome anomaly in 13 cases, and parental balanced chromosome translocation in 7 cases. One mother was a haemophilia A carrier. Two mothers over 40 were found to be carrying a 21-trisomic fetus. In the group of parental balanced translocation one fetus showed an unbalanced translocation karyotype, two were karyotypically normal and four exhibited a balanced translocation identical with that of the parents. A therapeutic abortion was performed in the case of the unbalanced translocation, the two trisomic fetuses, and a male fetus of the haemophilia A carrier mother. After the abortion the prenatal chromosome findings were confirmed by cell cultures from fetal tissues. No immediate complications due to the amniocentesis were recorded, but two term fetuses died antenatally, one child was delivered prematurely, and one pregnancy terminated spontaneously foru weeks after the amniocentesis. Any casual relationship to the puncture was unlikely in these cases. All other pregnancies had a normal course and the outcome was in agreement with the prenatal studies. Although indications for prenatal karyotype analyses are evident in pregnancies at risk due to parental balanced translocation karyotype and advanced maternal age, the need for large-scale screening programmes is questionable, because the decision should be in the hands of the parents.

Amniocentesis↗
PubMed1992

Trisomy 15 with loss of the paternal 15 as a cause of Prader-Willi syndrome due to maternal disomy.

Uniparental disomy has recently been recognized to cause human disorders, including Prader-Willi syndrome (PWS). We describe a particularly instructive case which raises important issues concerning the mechanisms producing uniparental disomy and whose evaluation provides evidence that trisomy may precede uniparental disomy in a fetus. Chorionic villus sampling performed for advanced maternal age revealed trisomy 15 in all direct and cultured cells, though the fetus appeared normal. Chromosome analysis of amniocytes obtained at 15 wk was normal in over 100 cells studied. The child was hypotonic at birth, and high-resolution banding failed to reveal the deletion of 15q11-13, a deletion which is found in 50%-70% of patients with PWS. Over time, typical features of PWS developed. Molecular genetic analysis using probes for chromosome 15 revealed maternal disomy. Maternal nondisjunction with fertilization of a disomic egg by a normal sperm, followed by loss of the paternal 15, is a likely cause of confined placental mosaicism and uniparental disomy in this case of PWS, and advanced maternal age may be a predisposing factor.

Adult↗
PubMed2026

Maternal age as a driver of genome instability: mechanisms linking aneuploidy, mutagenesis and mitochondrial dysfunction.

Advanced maternal age is a well-established risk factor for adverse reproductive outcomes due to increased rates of aneuploidy. However, emerging evidence indicates that the genetic consequences of maternal aging extend well beyond chromosome mis-segregation. Aging oocytes acquire a broad spectrum of genetic abnormalities, including maternally derived nuclear de novo mutations (DNMs) and mitochondrial DNA mutations, together with epigenetic dysregulation of DNA methylation and post-translational modification levels. These changes reflect the unique biology of the female germline in which oocytes remain arrested in meiotic prophase I for decades. Age-related deterioration of key processes, such as erosion of cohesion complexes, altered meiotic recombination, and weakened spindle assembly checkpoint surveillance collectively destabilize meiotic chromosome architecture, directly driving chromosome mis-segregation. At the same time, accumulation of endogenous DNA damage and declining DNA damage and repair processes increase the chances of transmitting lesions that can be converted into sequence-level mutations during the earliest embryonic divisions, when genome maintenance relies exclusively on maternal factors. High-resolution sequencing studies further demonstrate that maternal aging is associated with increased DNMs burden in both nuclear and mitochondrial DNA. Together, these findings support a model in which maternal aging is a driver of genome-wide instability that links aneuploidy and mutagenesis through shared defects in meiotic surveillance, declining DNA repair efficiency, and mitochondrial function. This framework positions delayed childbearing as a multifaceted genetic risk factor that extend beyond aneuploidy to include mutations and other genomic alterations that can impact intergenerational genetic risk.

Aneuploidy↗
PubMed1992

Prenatal cytogenetic diagnosis in amniocentesis.

From 1982 to 1990, cytogenetic studies were successfully conducted in 2,975 (96.19%) of the 3,096 pregnant women who underwent amniocentesis. The average maternal age was 33.7 years and the average gestational age was 18.1 weeks. Common indications of amniocentesis included advanced maternal age (AMA) (54.76%), previous fetus with chromosomal aberrations (6.82%) or gross anomalies (5.01%), intrauterine gross anomaly (4.97%) and maternal exposure to drugs or radiation (5.28%). Among the 89 cases (2.99%) with detected chromosomal aberrations, 53 were numeric (31 trisomies, 21 sex chromosome aberrations and one tripoidy) and 36 were structural (six de novo and 30 hereditary structural rearrangement). The incidence of chromosomal aberrations was 2.03% in cases with AMA. While only four of the 143 cases with previous fetal trisomy 21 had recurrence, the recurrent rate was 90.91% in 11 cases with previous fetal chromosomal translocation. Thirty (20.27%) of the 148 cases with abnormal sonograms showed chromosomal aberrations. Certain congenital anomalies are closely associated with cytogenetic changes: duodenal atresia and trisomy 21; cystic hygroma and 45,X; and polyhydramnios and trisomy 18. Only two of the 157 cases with indications of drug or radiation exposure had abnormal cytogenetic studies. Two of the 53 cases with detected numerical aberrations (47,XXY and 47,XXX) and 27 cases with hereditary structural rearrangement elected to continue their pregnancies. All of these babies were delivered without gross anomalies. This study suggests that for prenatal diagnosis. However, complementary measures, such as routine antenatal ultrasound and maternal serum alphafetoprotein, should be added to increase the efficacy of genetic amniocentesis.

Adolescent↗