Screening for Down's syndrome

Psychological consequences for parents of false negative results on prenatal screening for Down's syndrome: retrospective interview study

OBJECTIVE

To determine the psychological consequences for parents of children with Down's syndrome of having received a false negative result on prenatal screening.

DESIGN

Comparison of adjustment of parents who received a false negative result with that of parents not offered a test and those who declined a test.

SETTING

Parents were interviewed in their own homes.

PARTICIPANTS

Parents of 179 children with Down's syndrome (mean age 4 (range 2-6) years).

MAIN OUTCOME MEASURES

Anxiety, depression, parenting stress, attitudes towards the child, and attributions of blame for the birth of the affected child.

RESULTS

Overall, regardless of screening history, parents adjusted well to having a child with Down's syndrome. Compared with mothers who declined a test, mothers in the false negative group had higher parenting stress (mean score 81.2 v 71.8, P=0.016, 95% confidence interval for the difference 1.8 to 17.0) and more negative attitudes towards their children (124.9 v 134.2, P=0. 009, -16.2 to -2.4). Fathers in the false negative group had higher parenting stress test scores (77.8 v 70.0, P=0.046, 1.5 to 14.2) than fathers not offered a test. Mothers in the false negative group were more likely to blame others for the outcome than mothers who had not been offered the test (28% v 13%, P=0.032, 3% to 27%). Mothers and fathers in the false negative group were more likely to blame others for this outcome than parents who had declined a test (mothers 28% v 0%, P=0.001, 19% to 37%; fathers 27% v 0%, P=0.004, 17% to 38%). Blaming others was associated with poorer adjustment for mothers and fathers.

CONCLUSIONS

A false negative result on prenatal screening seems to have a small adverse effect on parental adjustment evident two to six years after the birth of an affected child.

Prospective study of prenatal screening for Down's syndrome with free beta human chorionic gonadotrophin

OBJECTIVE

To assess the value and impact of a screening programme for Down's syndrome that uses the two maternal serum markers: alpha fetoprotein and free beta human chorionic gonadotrophin.

DESIGN

All women booked into clinics were screened. Further tests were offered to women with a risk of one in 300 or greater of having an affected baby. Follow up of outcome of all pregnancies.

SETTING

Biochemical screening laboratory serving two health districts.

SUBJECTS

8179 women of all ages with singleton pregnancies screened between 15 and 22 weeks' gestation from 1 April 1991 to 31 March 1992.

MAIN OUTCOME MEASURES

Detection rate of Down's syndrome, false positive rate, uptake of screening, uptake of amniocentesis in women identified as at increased risk, prevalence of Down's syndrome at birth.

RESULTS

Overall 89% (8317/9345) of women underwent screening. The rate of detection of Down's syndrome was 69% (11/16; 95% confidence interval 41 to 89%) with a 5.2% false positive rate (426/179; 4.7 to 5.7%). In women under 30 the detection rate was 50% (four out of eight; 32 to 86%) Uptake of amniocentesis was 89% (389/437), resulting in a reduction of prevalence of Down's syndrome at birth from 1.1 per 1000 in previous years (66/59,696) to 0.4 per 1000 during the screening year (4/9345). Additionally, several other abnormalities were identified.

CONCLUSION

The benefit of a high detection rate with this approach and the additional anomalies identified should encourage others to introduce screening programmes for Down's syndrome that use free beta human chorionic gonadotrophin and alpha fetoprotein.