Detection Rates for Aneuploidy by First-Trimester and Sequential Screening.

OBJECTIVE: To estimate detection rates for aneuploidy by first-trimester and sequential screening. METHODS: The study included women with singleton pregnancies who participated in the California Prenatal Screening Program with estimated delivery dates from August 2009 to December 2012 who had first- or first- and second-trimester (sequential) screening. Detection rates were measured for target (trisomies 21 and 18) and other aneuploidies identified from the California Chromosome Defect Registry. RESULTS: Of 452,901 women screened, 17,435 (3.8%) were screen-positive for Down syndrome only; 433 (0.1%) for trisomy 18 only; 1,689 (0.4%) for both Down syndrome and trisomy 18; and 2,947 (0.7%) for neural tube defects, Smith-Lemli-Opitz syndrome, or for multiple conditions. The detection rates were Down syndrome-92.9% (95% confidence interval [CI] 91.4-94.2); trisomy 18-93.2% (95% CI 90.5-95.9); trisomy 13-80.4% (95% CI 73.9-86.9); 45,X-80.1% (95% CI 73.9-86.3), and triploidy-91.0% (95% CI 84.2-97.9). Overall, the detection rate for chromosome abnormalities was 81.6% (95% CI 80.0-83.1) at an overall false-positive rate of 4.5%. CONCLUSION: First-trimester and sequential screening are sensitive and specific for the broad range of karyotype abnormalities seen in the population. LEVEL OF EVIDENCE: II.

Risk of critical congenital heart defects by nuchal translucency norms.

OBJECTIVE: The purpose of this study was to compare the performance of first-trimester nuchal translucency (NT) cutoff of ≥3.5 mm with NT percentiles that were calculated for crown-rump length to identify fetuses with critical congenital heart defects (CCHDs). STUDY DESIGN: This was a population-level study of singleton pregnancies in California with NT measurements performed between 11 and 14 weeks of gestation. Eligible cases were those that resulted in live births from 2009-2010 and had information about the presence or absence of CCHDs available in the hospital discharge records through age 1 year (n = 76,089). Logistic binomial regression methods were used to compare the rate of CCHDs by an NT percentile for crown-rump length and millimeter cutpoints. RESULTS: Compared with fetuses with an NT measurement of <90th percentile, fetuses with an NT of ≥99th percentile were >5 times as likely to have a CCHD (1.3% vs 0.2%; relative risk, 5.66; 95% confidence interval, 3.19-10.04) and fetuses with an NT measurement ≥3.5 mm were >12 times as likely to have a CCHD (2.8% vs 0.2%; relative risk, 12.28; 95% confidence interval, 5.11-29.51). NT ≥99th percentile had a sensitivity of 5.8% and a specificity of 98.9% for the detection of CCHDs compared with 2.6% and 99.8% for NT ≥3.5 mm. CONCLUSION: Results show that NT measurements of ≥99th percentile and ≥3.5 mm are not equivalent and that substantial risk for CCHD extends to the less restrictive ≥99th percentile cutpoint. Data suggest that the use of this cutpoint compared with the current standard could double the number of CCHDs that are identified based on NT risk.

Risk of selected structural abnormalities in infants after increased nuchal translucency measurement.

OBJECTIVE: We sought to examine the association between increased first-trimester fetal nuchal translucency (NT) measurement and major noncardiac structural birth defects in euploid infants. STUDY DESIGN: Included were 75,899 singleton infants without aneuploidy or critical congenital heart defects born in California in 2009 through 2010 with NT measured between 11-14 weeks of gestation. Logistic binomial regression was employed to estimate relative risks (RRs) and 95% confidence intervals (CIs) for occurrence of birth defects in infants with an increased NT measurement (by percentile at crown-rump length [CRL] and by ≥3.5 mm compared to those with measurements <90th percentile for CRL). RESULTS: When considered by CRL adjusted percentile and by measurement ≥3.5 mm, infants with a NT ≥95th percentile were at risk of having ≥1 major structural birth defects (any defect, RR, 1.6; 95% CI, 1.3-1.9; multiple defects, RR, 2.1; 95% CI, 1.3-3.4). Infants with a NT measurement ≥95th percentile were at particularly high risk for pulmonary, gastrointestinal, genitourinary, and musculoskeletal anomalies (RR, 1.6-2.7; 95% CI, 1.1-5.4). CONCLUSION: Our findings demonstrate that risks of major pulmonary, gastrointestinal, genitourinary, and musculoskeletal structural birth defects exist for NT measurements ≥95th percentile. The ≥3-fold risks were observed for congenital hydrocephalus; agenesis, hypoplasia, and dysplasia of the lung; atresia and stenosis of the small intestine; osteodystrophies; and diaphragm anomalies.

Obstetric, perinatal, and fetal outcomes in pregnancies with false-positive integrated screening results.

OBJECTIVE: To assess the risk of adverse obstetric, perinatal, and fetal outcomes for pregnant women participating in prenatal sequential integrated screening through the California Prenatal Screening Program who had a false-positive screening result. METHODS: Women who underwent first- and second-trimester prenatal integrated screening plus nuchal translucency measurement with outcome information available were included. Fetuses and neonates with chromosomal or neural tube defects were excluded. We compared the risk of adverse outcomes for all women with a positive screening result compared with a 10% random sample of women with a negative screening result. Logistic binomial regression was used to compare adverse outcomes in screen-positive compared with screen-negative women. RESULTS: We identified 9,051 screen-positive and 30,928 screen-negative pregnancies with outcome information available. Compared with screen-negative pregnancies, screen-positive women were more likely to be diagnosed with preeclampsia, placenta previa, or abruption (7.6% screen-positive, 3.8% screen-negative; relative risk 1.7, 95% confidence interval [CI] 1.6-1.8) or experience fetal loss before 20 weeks of gestation (1.9% screen-positive, 0.2% screen-negative; relative risk 3.5, 95% CI 3.2-3.8). Women with positive results for more than one screened condition were at substantially greater risk of fetal and neonatal mortality (relative risks 33.6-156.7, 95% CIs 21.8-194.4). CONCLUSION: Among pregnancies without chromosomal or neural tube defects, prenatal sequential integrated screening provides information regarding risk across a variety of adverse pregnancy outcomes.

The California Prenatal Screening Program: "options and choices" not "coercion and eugenics".

The California Prenatal Screening Program is designed to make prenatal screening available to the state's large and diverse population. The Program provides information to women which will allow them to make informed choices regarding prenatal screening and prenatal diagnosis. Since the Program's inception in 1986, women in California have had the option to participate in prenatal screening or to decline prenatal screening. The California Program offers prenatal diagnostic services to women whose screening tests indicate an increased risk for birth defects, including Down syndrome. Women can decline any or all of these follow-up services. Genetic counseling, diagnostic services, and the presentation of diagnostic results are performed by medical professionals (not State staff) who follow established guidelines for nondirective counseling. Program data clearly demonstrate that women in California have a wide range of options and make a wide range of choices regarding prenatal screening and prenatal diagnosis. California's comprehensive Prenatal Screening Program promotes optimal care for all women within all options and choices. The important and necessary communication among organizations and stakeholders involved in prenatal screening and diagnosis, and in related care for pregnant women and for people with Down syndrome, is not served by misrepresentation and inflammatory rhetoric.