Chromosomal abnormalities: subgroup analysis by maternal age and perinatal features in zhejiang province of China, 2011-2015

Influence of parental age on chromosomal abnormalities in PGT-A embryos: exponentially increasing in the mother and completely null in the father

PURPOSE

To study the influence of parental age on aneuploidy rates (AR) in PGT-A cycles and on the recurrence rate.

METHODS

A total of 16,029 PGT-A cycles were studied over a 9-year period. The median age was 40.0 [37.0; 41.0] in women and 40.0 [37.0; 43.0] in men. In 48.3%, the biopsy was performed on day 3 embryos (D3E) and in 51.7% on blastocysts (79.5% using NGS).

RESULTS

In women, the AR was almost constant at < 50% until the age of 35 but increased steadily to reach > 90% at 44. The AR pattern varied according to embryo stage and was considerably higher in D3E, with a steeper curve. A U-pattern was observed in D3E, whereas this was not seen in blastocysts. In the blastocysts analyzed using NGS, trisomy 21 increased sixfold (from < 1% at < 30 to nearly 5% in women aged 40), whereas trisomies 13 and 18 increased their frequency twofold. After 3 biopsied blastocysts studied using NGS, 100% of women aged ≤ 30 had at least 1 euploid embryo, vs 96% aged 31-35, almost 80% aged 36-40, 50% aged 41-45, and 33% aged 46-50. In terms of the man's age, the non-adjusted analysis revealed a correlation with AR. However, after correcting for the woman's age, no correlation was observed. The man's age was not associated with any of the aneuploidies potentially resulting in a newborn.

CONCLUSIONS

Carrying out PGT-A systematically in IVF cycles from the age of 38-39 is highly recommended. Advanced paternal age does not carry an increased risk of aneuploidy for the embryo and does not in itself constitute an indication for PGT-A.

Multivariate logistic regression analysis of risk factors for birth defects: a study from population-based surveillance data

OBJECTIVE

To explore risk factors for birth defects (including a broad range of specific defects).

METHODS

Data were derived from the Population-based Birth Defects Surveillance System in Hunan Province, China, 2014-2020. The surveillance population included all live births, stillbirths, infant deaths, and legal termination of pregnancy between 28 weeks gestation and 42 days postpartum. The prevalence of birth defects (number of birth defects per 1000 infants) and its 95% confidence interval (CI) were calculated. Multivariate logistic regression analysis (method: Forward, Wald, α = 0.05) and adjusted odds ratios (ORs) were used to identify risk factors for birth defects. We used the presence or absence of birth defects (or specific defects) as the dependent variable, and eight variables (sex, residence, number of births, paternal age, maternal age, number of pregnancies, parity, and maternal household registration) were entered as independent variables in multivariate logistic regression analysis.

RESULTS

Our study included 143,118 infants, and 2984 birth defects were identified, with a prevalence of 20.85% (95%CI: 20.10-21.60). Multivariate logistic regression analyses showed that seven variables (except for parity) were associated with birth defects (or specific defects). There were five factors associated with the overall birth defects. The risk factors included males (OR = 1.49, 95%CI: 1.39-1.61), multiple births (OR = 1.44, 95%CI: 1.18-1.76), paternal age < 20 (OR = 2.20, 95%CI: 1.19-4.09) or 20-24 (OR = 1.66, 95%CI: 1.42-1.94), maternal age 30-34 (OR = 1.16, 95%CI: 1.04-1.29) or > = 35 (OR = 1.56, 95%CI: 1.33-1.81), and maternal non-local household registration (OR = 2.96, 95%CI: 2.39-3.67). Some factors were associated with the specific defects. Males were risk factors for congenital metabolic disorders (OR = 3.86, 95%CI: 3.15-4.72), congenital limb defects (OR = 1.34, 95%CI: 1.14-1.58), and congenital kidney and urinary defects (OR = 2.35, 95%CI: 1.65-3.34). Rural areas were risk factors for congenital metabolic disorders (OR = 1.21, 95%CI: 1.01-1.44). Multiple births were risk factors for congenital heart defects (OR = 2.09, 95%CI: 1.55-2.82), congenital kidney and urinary defects (OR = 2.14, 95%CI: 1.05-4.37), and cleft lip and/or palate (OR = 2.85, 95%CI: 1.32-6.15). Paternal age < 20 was the risk factor for congenital limb defects (OR = 3.27, 95%CI: 1.10-9.71), 20-24 was the risk factor for congenital heart defects (OR = 1.64, 95%CI: 1.24-2.17), congenital metabolic disorders (OR = 1.56, 95%CI: 1.11-2.21), congenital limb defects (OR = 1.61, 95%CI: 1.14-2.29), and congenital ear defects (OR = 2.13, 95%CI: 1.17-3.89). Maternal age < 20 was the risk factor for cleft lip and/or palate (OR = 3.14, 95%CI: 1.24-7.95), 30-34 was the risk factor for congenital limb defects (OR = 1.37, 95%CI: 1.09-1.73), >=35 was the risk factor for congenital heart defects (OR = 1.51, 95%CI: 1.14-1.99), congenital limb defects (OR = 1.98, 95%CI: 1.41-2.78), and congenital ear defects (OR = 1.82, 95%CI: 1.06-3.10). Number of pregnancies = 2 was the risk factor for congenital nervous system defects (OR = 2.27, 95%CI: 1.19-4.32), >=4 was the risk factor for chromosomal abnormalities (OR = 2.03, 95%CI: 1.06-3.88) and congenital nervous system defects (OR = 3.03, 95%CI: 1.23-7.47). Maternal non-local household registration was the risk factor for congenital heart defects (OR = 3.57, 95%CI: 2.54-5.03), congenital metabolic disorders (OR = 1.89, 95%CI: 1.06-3.37), congenital limb defects (OR = 2.94, 95%CI: 1.86-4.66), and congenital ear defects (OR = 3.26, 95%CI: 1.60-6.65).

CONCLUSION

In summary, several risk factors were associated with birth defects (including a broad range of specific defects). One risk factor may be associated with several defects, and one defect may be associated with several risk factors. Future studies should examine the mechanisms. Our findings have significant public health implications as some factors are modifiable or avoidable, such as promoting childbirths at the appropriate age, improving the medical and socio-economic conditions of non-local household registration residents, and devoting more resources to some specific defects in high-risk groups, which may help reducing birth defects in China.

Maternal age and the risk of fetal aneuploidy: A nationwide cohort study of more than 500 000 singleton pregnancies in Denmark from 2008 to 2017

INTRODUCTION

In this register-based study of pregnancies in Denmark, we assessed the associations between maternal age and the risk of fetal aneuploidies (trisomy 21, trisomy 18, trisomy 13, triploidy, monosomy X and other sex chromosome aberrations). Additionally, we aimed to disentangle the maternal age-related effect on fetal aneuploidies by cases with translocation trisomies and mosaicisms.

MATERIAL AND METHODS

We followed a nationwide cohort of 542 375 singleton-pregnant women attending first trimester screening in Denmark between 2008 and 2017 until delivery, miscarriage or termination of pregnancy. We used six maternal age categories and retrieved information on genetically confirmed aneuploidies of the fetus and infant from the national cytogenetic register.

RESULTS

We confirmed the known associations between advanced maternal age and higher risk of trisomy 21, 18, 13 and other sex chromosome aberrations, especially in women aged ≥35 years, whereas we found no age-related associations with triploidy or monosomy X. Cases with translocation trisomies and mosaicisms did not influence the overall reported association between maternal age and aneuploidies.

CONCLUSION

This study provides insight into the accurate risk of fetal aneuploidies that pregnant women of advanced ages encounter.

The effect of China's birth policy changes on birth defects-A large hospital-based cross-sectional study

A retrospective analysis of birth data hospital-based obtained from 14 monitoring areas in the Huaihe River Basin from 2009 to 2019 was conducted. Trend in the total prevalence of birth defects (BDs) and subgroups were analyzed using the Joinpoint Regression model. The incidence of BDs increased gradually from 118.87 per 10,000 in 2009 to 241.18 per 10,000 in 2019 (AAPC = 5.91, P < 0.001). Congenital heart diseases were the most common subtype of BDs. The proportion of maternal age younger than 25 decreased but the age 25-40 years increased significantly (AAPC<20=-5.58; AAPC20-24=-6.38; AAPC25-29 = 5.15; AAPC30-35 = 7.07; AAPC35-40 = 8.27; All P < 0.05). Compared with the one-child policy period, the risk of BDs was greater for groups among maternal age younger than 40 years during the partial and universal two-child policy period (P < 0.001). The incidence of BDs and the proportion of women with advanced maternal age in Huaihe River Basin is increasing. There was an interaction between changes in birth policy and the mother's age on the risk of BDs.

Evaluation of chromosomal abnormalities in the postnatal cohort: A single-center study on 14,242 patients

BACKGROUND AND AIM

Chromosomal analysis is a laboratory technique used to examine the chromosomes of an individual, offering insights into chromosome numbers, structures, and arrangements to diagnose and comprehend genetic diseases. This retrospective study provides a comprehensive understanding of the distribution by indications in a large cohort of 14,242 patients and the frequency of chromosomal abnormalities in different clinical populations.

METHOD

The study examined various indications for karyotype evaluation, with recurrent pregnancy loss being the most common indication, followed by intellectual disability, dysmorphic features, congenital anomalies, and developmental delay.

RESULTS

The overall chromosomal abnormality rate was found to be 5.4%, with numerical abnormalities accounting for the majority of cases (61.7%). Trisomies, particularly trisomy 21, were the most frequent numerical abnormalities. In terms of structural abnormalities, inversions and translocations were the most commonly identified. The rates of chromosomal anomalies varied in specific indications such as amenorrhea, disorders of sex development, and Turner syndrome. The study also highlighted significant differences between males and females in the presence of chromosomal abnormalities across certain indications. Males exhibited a higher incidence of chromosomal abnormalities in cases of Down syndrome and infertility, whereas females showed higher abnormalities in terms of recurrent pregnancy loss.

CONCLUSION

While this study provides valuable insights into the frequency and distribution of chromosomal abnormalities, it has limitations, including its retrospective design and reliance on data from a single medical genetics department. Nevertheless, the findings emphasize the importance of karyotype analysis in diagnosing chromosomal disorders and providing appropriate management, while also pointing to potential gender-related variations in chromosomal abnormalities that warrant further investigation.

Factors associated with the development of epilepsy in very low birth weight infants

BACKGROUND

The survival rate of very low birth weight (VLBW) infants has recently improved. However, the occurrence of and factors associated with epilepsy in VLBW infants remain unknown. This study aimed to clarify the incidence, characteristics, and factors associated with epilepsy development in VLBW infants.

METHODS

All VLBW infants admitted to our hospital between 2012 and 2017 were included in this study. VLBW infants with a follow-up period of <1 year were excluded. Chromosomal abnormalities, brain anomalies, severe intraventricular hemorrhage (IVH), cystic periventricular leukomalacia (PVL), and hypoxic ischemic encephalopathy (HIE) were considered to be risk factors.

RESULTS

Epilepsy occurred in 21/526 (4.0%) VLBW infants. Chromosomal abnormalities, brain anomalies, severe IVH, cystic PVL, HIE, neonatal seizures, advanced maternal age, maternal diabetes mellitus, no administration of antenatal corticosteroids, and low Apgar scores at 1 and 5 min were associated with a risk of epilepsy. The median time to epilepsy onset was 8 months (range: 0-59 months), and the onset occurred within 2 years in 15/21 patients (71.4%) and within 4 years in 18/21 patients (85.7%). VLBW infants with risk factors developed epilepsy earlier and at a significantly higher rate than those without risk factors. Among infants who had risk factors and who developed epilepsy, 86.7% did so within 2 years of age, compared to 33.3% of those who developed epilepsy but did not have risk factors.

CONCLUSION

These findings regarding factors associated with a risk of development of epilepsy and temporal feature of epilepsy may contribute to the development of monitoring and treatment protocols for epilepsy in VLBW infants.

Independent factors associated with birth defects during the whole of pregnancy in Shenyang City, China: a case-control study

Background

Birth defects, as a kind of diseases that seriously affect human life, have always attracted much attention. In the past, perinatal data have been studied for birth defects. This study analyzed the surveillance data of birth defects during the perinatal period and the whole of pregnancy, as well as the independent influencing factors, to help to minimize their risk of birth defects.

Methods

A total of 23,649 fetuses delivered in the hospital from January 2017 to December 2020, were enrolled in this study. There were 485 cases of birth defects, including live births and stillbirths by detailed inclusion and exclusion criteria. Maternal and neonatal clinical data were collated to analyze the influencing factors associated with birth defects. Pregnancy complications and comorbidities were diagnosed according to the criteria of the Chinese Medical Association. Univariate and multivariate logistic regression models were used to investigate the association between independent variables and birth defect events.

Results

The incidence of birth defects during the whole of pregnancy was 175.46/10,000, while the incidence of perinatal birth defects was 96.22/10,000. The birth defect group had significantly higher maternal age, gravidity, parity, rate of preterm birth, cesarean section (CS) rate, scarred uterus, stillborn, and male newborns compared to the control group. Multivariate logistic regression model analysis showed that preterm birth [odds ratio (OR): 1.69, 95% confidence interval (CI): 1.01 to 2.86], CS (OR: 1.46, 95% CI: 1.08 to 1.98), scarred uterus (OR: 1.70, 95% CI: 1.01 to 2.85), and low birth weight (OR >4 compared to the other two classes) were significantly associated with birth defects during the whole of pregnancy (all P<0.05). The independent influencing factors associated with perinatal birth defects included CS (OR: 1.43, 95% CI: 1.05 to 1.93), gestational hypertension (OR: 1.70, 95%: 1.04 to 2.78), and low birth weight (OR >3.70 compared to the other two classes).

Conclusions

The discovery and monitoring of known influencing factors associated with birth defects, such as, preterm birth, gestational hypertension, low birth weight, should be enhanced. For the controllable influencing factors, obstetrics providers should work with patients to minimize their risk of birth defects.

The trend in delayed childbearing and its potential consequences on pregnancy outcomes: a single center 9-years retrospective cohort study in Hubei, China

BACKGROUND

Due to the advancement of modern societies, the proportion of women who delay childbearing until or beyond 30 years has dramatically increased in the last three decades and has been linked with adverse maternal-neonatal outcomes.

OBJECTIVE

To determine the trend in delayed childbearing and its negative impact on pregnancy outcomes.

MATERIAL AND METHODS

A tertiary hospital-based retrospective study was conducted in Wuhan University Renmin Hospital, Hubei Province, China, during the years 2011-2019. The joinpoint regression analysis was used to find a trend in the delayed childbearing and the multiple binary logistic regression model was used to estimate the association between maternal age and pregnancy outcomes.

RESULTS

Between 2011 and 2019, the trend in advanced maternal age (AMA ≥35 years) increased by 75% [AAPC 7.5% (95% CI: - 10.3, 28.9)]. Based on maternal education and occupation, trend in AMA increased by 130% [AAPC 11.8% (95% CI: 1.1, 23.7)] in women of higher education level, and 112.5% [AAPC 10.1% (95% CI: 9.4, 10.9)] in women of professional services. After adjusting for confounding factors, AMA was significantly associated with increased risk of gestational hypertension (aOR 1.5; 95% CI: 1.2, 2.1), preeclampsia (aOR 1.6; 95% CI: 1.4, 1.9), sever preeclampsia (aOR 1.7; 95% CI: 1.1, 2.6), placenta previa (aOR 1.8; 95% CI: 1.5, 2.2), gestational diabetes mellitus (aOR 2.5; 95% CI: 2.3, 2.9), preterm births (aOR 1.6; 95% CI: 1.4, 1.7), perinatal mortality (aOR 1.8; 95% CI: 1.3, 2.3), and low birth weight (aOR 1.3; 95% CI: 1.2, 1.4) compared with women aged < 30 years.

CONCLUSION

Our findings show a marked increase in delayed childbearing and its negative association with pregnancy outcomes.

Changes in the birth prevalence of orofacial clefts in Japan: Has the birth prevalence of orofacial clefts been affected by improved accuracy of prenatal diagnosis?

We have been conducting a survey on the birth prevalence of orofacial clefts, including cleft lip with or without cleft palate and cleft palate, in the Tokai area in central Japan every year for 37 years. Along with the yearly trends in the birth prevalence of orofacial clefts in that area for the past 37 years, we discuss whether the artificial abortion rate of fetuses with orofacial clefts has increased through the improved performance of ultrasonic imaging equipment. We also compare the yearly trends in the birth prevalence of congenital anomalies, including orofacial clefts, in Japan with those in other countries or areas where artificial abortion due to birth defects is legally permitted, and discuss the impact of improved accuracy of ultrasound imaging on the rate of artificial termination of pregnancy. The fact that the birth prevalence of orofacial clefts has basically remained unchanged for more than 30 years, even with recent more detailed prenatal diagnosis based on the improvement of ultrasonic diagnostic equipment, has allowed us tentatively to conclude that prenatal diagnosis is not currently threatening the right to life of the fetuses with orofacial clefts.

Maternal exposure to PM2.5 was linked to elevated risk of stillbirth

BACKGROUND

More and more studies began to explore the hazardous health effects of PM2.5, but few reported its impacts on stillbirth. The sparse results were inconsistent and remained to be integrated. Therefore, we aimed to reveal the association between maternal exposure to PM2.5 and stillbirth.

METHODS

In this meta-analysis, we searched PubMed, Web of Science, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases for related articles written in English and published before October 18, 2020. Study selection was conducted according to the predetermined criteria and data attraction was done with predesigned form. A new instrument was applied to conduct the risk of bias assessment. And random-effect models were used to pool the estimates.

RESULTS

A total of 3655 records were identified from the databases, but only 7 studies were ultimately included in this study. Positive association was found between the maternal exposure to PM2.5 (per 10 μg/m3 increased) in the entire pregnancy (OR: 1.15, 95% CI: 1.07-1.25) and third trimester (OR: 1.09, 95% CI: 1.01-1.18) and stillbirth, but the association between the maternal exposure to PM2.5 (per 10 μg/m3 increased) in the first trimester (OR: 1.01, 95% CI: 0.90-1.13) and second trimester (OR: 1.06, 95% CI: 0.98-1.14) and stillbirth was not statistically significant. Besides, there was no publication bias.

CONCLUSIONS

Maternal exposure to PM2.5 in the entire pregnancy and third trimester was associated with elevated risk of stillbirth. However, due to the high heterogeneity, further pathophysiological researches and high quality population studies were still warranted.

A cascade of interventions: A classification tree analysis of the determinants of primary cesareans in Australian public hospitals

BACKGROUND

Both globally and in Australia, there has been a sharp rise in cesarean births (CB). Commonly, this rise has been attributed to the changing epidemiology of women giving birth. A significant body of knowledge exists on the risk factors associated with a greater need for cesarean. Yet, we have little information on the reasons recorded by clinicians as to why cesareans are provided. This study aimed to explore the drivers of primary cesareans in Australian public hospitals.

METHODS

Using a linked administrative data set, the frequency and percent of mothers' characteristics were compared between those who had a cesarean birth and those who had a vaginal birth (n = 98 967) with no history of previous cesareans in Queensland public hospitals between July 1, 2012, and June 30, 2015. The top 10 reasons recorded by clinicians for a primary cesarean were reported. Using a machine-learning algorithm, two decision trees were built to determine factors driving primary cesarean birth.

RESULTS

"Labour and delivery complicated by fetal heart rate anomaly" (23%) and "primary inadequate contractions" (22.8%) were the top two reasons for a primary cesarean birth. The most common characteristics among mothers who had fetal heart rate anomalies were as follows: artificial rupture of membranes (39%), oxytocin (32%), no obstruction of labor (42%), and epidural (52%). For women who had primary inadequate contractions, the most common characteristics were as follows: epidural (33%), oxytocin (49%), artificial rupture of membranes (45%), and fetal stress (56%).

CONCLUSIONS

Efforts should be made by health practitioners during the antenatal period to maximize the use of preventative measures that minimize the need for medical interventions.

Prevalence and risk factors of radial ray deficiencies: A population-based case-control study

Radial ray deficiency is the most common congenital deficiency of the upper limb. The aim of our study was to investigate maternal risk factors for radial ray deficiencies. We conducted a nationwide population-based case-control study using national registers. All cases with a radial ray deficiency born between 1996 and 2008 were included in the study and compared with five controls without limb deficiency. In total, 115 (10 isolated, 18 with multiple congenital anomalies, and 87 syndromic) cases with radial ray deficiencies were identified and compared with 575 matched controls. The total prevalence in Finland was 1.22 per 10,000 births. No significant risk factors were observed for nonsyndromic cases. In the syndromic group, advanced maternal age (≥35 years) increased the risk of radial aplasia (aOR 2.45, 95% CI 1.37-4.36), and a similar association was observed with multiple pregnancy (aOR 2.97, 1.16-7.62) and male sex (aOR 1.96, 1.18-3.25). Valproic acid was also a risk factor (p = .002). In conclusion, novel associations in the syndromic group of advanced maternal age and multiple pregnancy and increased risk of radial ray deficiencies were observed. Also, early reports on increased risk of RRD associated with valproate and male sex were supported by our results.

Changes in maternal age and prevalence of congenital anomalies during the enactment of China's universal two-child policy (2013-2017) in Zhejiang Province, China: An observational study

BACKGROUND

China implemented a partial two-child policy (2013) followed by a universal two-child policy (2015), replacing the former one-child policy mandated by the government. The changes affect many aspects of China's population as well as maternal and infant health, but their potential impact on birth defects (BDs) remains unknown. In this study, we investigated the associations of these policy changes with BDs in Zhejiang Province, China.

METHODS AND FINDINGS

We used data from the BD surveillance system in Zhejiang Province, China, which covers 90 hospitals in 30 urban districts and rural counties, capturing one-third of the total births in this province. To fully consider the time interval between conception and delivery, we defined the one-child policy period as data from 2013 (births from October 2012 to September 2013), the partial two-child policy period as data from 2015 (births from October 2014 to September 2015), and the universal two-child policy period as data from 2017 (births from October 2016 to September 2017). Data from 2009 and 2011 were also used to show the changes in the proportion of births to women with advanced maternal age (35 years and older) prior to the policy changes. Main outcome measures were changes in the proportion of mothers with advanced maternal age, prevalence of BDs, rankings of BD subtypes by prevalence, prenatal diagnosis rate, and live birth rate of BDs over time. A total of 1,260,684 births (including live births, early fetal losses, stillbirths, and early neonatal deaths) were included in the analyses. Of these, 644,973 (51.16%) births were to women from urban areas, and 615,711 (48.84%) births were to women from rural areas. In total, 135,543 (10.75%) births were to women with advanced maternal age. The proportion increased by 85.68%, from 8.52% in 2013 to 15.82% in 2017. However, it had remained stable prior to policy changes. Overall, 23,095 BDs were identified over the policy changes (2013-2017). The prevalence of BDs during 2013, 2015, and 2017 was 245.95, 264.86, and 304.36 per 10,000 births, respectively. Trisomy 21 and other chromosomal defects increased in both risk and ranking from 2013 to 2017 (crude odds ratio [95% confidence interval] 2.13 [1.75-2.60], from ranking 10th to 5th, and 3.63 [2.84-4.69], from ranking 16th to 6th, respectively). The prenatal diagnosis rate increased by 3.63 (2.2-5.1) percentage points (P < 0.001), from 31.10% to 34.72%, and identification of BDs occurred 1.88 (1.81-1.95) weeks earlier (P < 0.001). The live birth rate for infants with BDs born before 28 gestational weeks increased from 1.29% to 11.45%. The major limitations of this observational study include an inability to establish causality and the possible existence of unknown confounding factors, some of which could contribute to BDs.

CONCLUSIONS

In this study, we observed significant increases in maternal age and the prevalence of total and age-related anomalies following China's new two-child policy. Increases in live birth rate for infants with BDs born before 28 gestational weeks suggest that healthcare for very preterm births with BDs may be warranted in the future, as well as updating the definition of perinatal period.

Analysis of prenatal diagnosis before and after implementation of the two-child policy in northeastern China

The universal two-child policy has now been fully implemented in China. This change requires adaptations to maternal care and childcare systems, but the features of prenatal diagnosis before and after implementation of the policy have not been reported.We conducted a retrospective study of 6736 prenatal cytogenetic diagnoses performed on amniotic fluid cells over a 4-year period, including 2 years before and after implementation of the second child policy. Amniotic fluid cells collected through amniocentesis were cultured, harvested, and stained for chromosome analysis using standard laboratory protocols.The study included 3222 pregnant women referred before implementation of the policy, which we used as a control group, and 3514 pregnant women referred after policy implementation as an investigational study group. There were significantly fewer pregnant women aged <25 years in the investigational group than in the control group (P < .001). There were no significant between-group differences for other pregnant women aged >31 years and 27-28 years old (P > .05). A total of 358 cases with chromosomal abnormalities were diagnosed, including 129 (4%, 129/3222) in the control group which was significantly lower than the 229 (6.5%, 229/3514) in the study group (P < .001). In particular, significantly more trisomy 21 cases were observed in the study group than in the control group (120 vs 59). More pregnant women underwent non-invasive prenatal testing (NIPT) in the study group (46%) than in the control group (20%). In the study group, the average age of pregnant women who underwent NIPT was significantly higher than that of women who did not receive NIPT (P < .05). However, there were no significant between-group differences for the control group (P > .05).The number of cases with chromosomal abnormalities increased in northeastern China in the 2 years after implementation of the two-child policy. The number of pregnant women of advanced maternal age did not increase significantly, perhaps because of the widespread application of NIPT. However, the number of fetuses with Down syndrome increased significantly, suggesting that prenatal screening and diagnosis should be strengthened.

Ontogenetic and Pathogenetic Views on Somatic Chromosomal Mosaicism

Intercellular karyotypic variability has been a focus of genetic research for more than 50 years. It has been repeatedly shown that chromosome heterogeneity manifesting as chromosomal mosaicism is associated with a variety of human diseases. Due to the ability of changing dynamically throughout the ontogeny, chromosomal mosaicism may mediate genome/chromosome instability and intercellular diversity in health and disease in a bottleneck fashion. However, the ubiquity of negligibly small populations of cells with abnormal karyotypes results in difficulties of the interpretation and detection, which may be nonetheless solved by post-genomic cytogenomic technologies. In the post-genomic era, it has become possible to uncover molecular and cellular pathways to genome/chromosome instability (chromosomal mosaicism or heterogeneity) using advanced whole-genome scanning technologies and bioinformatic tools. Furthermore, the opportunities to determine the effect of chromosomal abnormalities on the cellular phenotype seem to be useful for uncovering the intrinsic consequences of chromosomal mosaicism. Accordingly, a post-genomic review of chromosomal mosaicism in the ontogenetic and pathogenetic contexts appears to be required. Here, we review chromosomal mosaicism in its widest sense and discuss further directions of cyto(post)genomic research dedicated to chromosomal heterogeneity.