Detection rates of abnormalities in over 10,000 amniotic fluid samples at a single laboratory.

BACKGROUND: A growing number of cytogenetic techniques have been used for prenatal diagnosis. This study aimed to demonstrate the usefulness of karyotyping, BACs-on-Beads (BoBs) assay and single nucleotide polymorphism (SNP) array in prenatal diagnosis during the second trimester based on our laboratory experience. METHODS: A total of 10,580 pregnant women with a variety of indications for amniocentesis were enrolled in this retrospective study between January 2015 and December 2020, of whom amniotic fluid samples were analysed in 10,320 women. The main technical indicators of participants in the three different technologies were summarized, and cases of chromosome abnormalities were further evaluated. RESULTS: The overall abnormality detection rate of karyotyping among all the amniotic fluid samples was 15.4%, and trisomy 21 was the most common abnormality (20.9%). The total abnormality detection rate of the BoBs assay was 5.6%, and the diagnosis rate of microdeletion/microduplication syndromes that were not identified by karyotyping was 0.2%. The detection results of the BoBs assay were 100.0% concordant with karyotyping analysis in common aneuploidies. Seventy (87.5%) cases of structural abnormalities were missed by BoBs assay. The total abnormality detection rate of the SNP array was 21.6%. The detection results of common aneuploidies were exactly the same between SNP array and karyotyping. Overall, 60.1% of structural abnormalities were missed by SNP array. The further detection rate of pathogenic significant copy number variations (CNVs) by SNP was 1.4%. CONCLUSIONS: Karyotyping analysis combined with BoBs assay or SNP array for prenatal diagnosis could provide quick and accurate results. Combined use of the technologies, especially with SNP array, improved the diagnostic yield and interpretation of the results, which contributes to genetic counselling. BoBs assay or SNP array could be a useful supplement to karyotyping.

Mediating Effects of Maternal Blood Triglycerides on the Relationship between Prepregnancy Body Mass Index and Fetal Macrosomia.

OBJECTIVE: To examine whether the association of prepregnancy body mass index (BMI) with fetal macrosomia is mediated through maternal circulating lipid concentrations during pregnancy. STUDY DESIGN: In this prospective cohort, 3011 eligible pregnant women were enrolled. Information on demographic characteristics were collected using questionnaires, and anthropometrics and laboratory tests were performed at 24 weeks of gestation and before delivery. Macrosomia was defined as birth weight ≥4000 g. Logistic regression and multivariable linear regression, adjusted for age, fetal sex, education, gestational weight gain, fasting blood glucose, gestational diabetes, gestational hypertension, gestational age at delivery, delivery mode, and parity, were used to assess the mediation path between prepregnancy BMI, maternal serum lipids, and fetal macrosomia. RESULTS: A total of 2454 participants with completed records were included in the final analyses. Among the maternal circulating lipid biomarkers, only triglyceride was significantly associated with both prepregnancy BMI and fetal macrosomia risk, adjusting for potential confounders. Mediation analyses demonstrated that the direct effect of prepregnancy BMI on fetal macrosomia was 0.0085 (95% CI, 0.0003-0.018; P < .05), the indirect effect mediated through maternal serum triglycerides was 0.0016 (95% CI, 0.0007-0.0029; P < .001), and the estimated proportion of mediated effect was 15.7% (P < .05). CONCLUSIONS: Maternal circulating triglycerides mediate the association of prepregnancy BMI with the risk of fetal macrosomia.