[Antenatal screening of maternal alpha-fetoprotein with dried-blood spot samples on filter paper].

Abnormal levels of maternal serum alphafetoprotein (AFP) have been used as a good biochemical marker for the screening of neural tube defects (NTD) and Down syndrome. From January 1988 to June 1989, we conducted a community-based maternal AFP screening program in Nan-Tou County, which is located in the middle of Taiwan. A total of 3,776 pregnant women, which accounted for about 42% of the total number of women pregnant during that period of time in Nan-Tou county, were screened using the filter paper blood collecting technique. Of those screened, 5.1% of them were found to be borderline positive for NTD (2.0 less than MoM less than 2.5). The screening positive rates for NTD (MoM greater than 2.5) and Down syndrome (Down's risk greater than 1/100) were 3.7% and 1.7%, respectively. Except for those lost to follow-up, 3 (2.1%) of the borderline cases were confirmed to have serious pregnancy complications (porencephaly, fetal demise, and imminent miscarriage). Eleven (10.8%) of the abnormal pregnancies, which included 1 case of possible hydrocephalus, 2 cases of anencephalus, and 1 case of triploid, were found in the NTD positive group. Six (18.7%) anomalies (1 Down syndrome, 1 hydatidiform mole, and 4 miscarriages) were detected in the increased Down's risk group. Totally, 20 adverse pregnancies, i.e. 0.5% (20/3,776) of the screened women, were confirmed in this screening program. No false-positive cases were reported, or were found among the 1,777 post-delivery questionnaires completed.(ABSTRACT TRUNCATED AT 250 WORDS)