Risk assessment of amniocentesis between 11 and 15 weeks: comparison to later amniocentesis controls.

We studied 693 consecutive early amniocenteses (prior to 15 weeks) and found a spontaneous abortion rate to 28 weeks' gestation of 1.5 per cent. A control group of women having standard amniocentesis (15-20 weeks) experienced a 0.6 per cent fetal loss in the same period. There were no other apparent differences between the two groups. Early amniocentesis results are generally available 4-6 weeks before standard amniocentesis and 1-3 weeks after chorionic villus sampling (CVS). Alpha-fetoprotein (AFP) can be accurately assayed in 11- to 15-week amniotic fluid samples but additional studies are necessary to determine the accuracy of neural tube defect (NTD) detection. Including the present study, over 5800 early amniocenteses have been reported and the results suggest that this is a relatively safe prenatal diagnostic test and an alternative to CVS and later amniocentesis.

Racial differences in maternal serum human chorionic gonadotropin and unconjugated oestriol levels.

We assayed maternal serum samples from 134 black and 268 white women from 16 to 18 weeks of gestation for intact human chorionic gonadotropin (hCG), and unconjugated oestriol (uE3). Serum from women with high (> or = 2.5 MOMs) or low (risk for Down syndrome > or = 1/365) maternal serum alpha-fetoprotein (MSAFP) levels were excluded. After correcting for maternal weight, we found that median hCG levels were 16 per cent higher in black women but uE3 levels were not significantly different. These results confirm three other studies for hCG and one study for uE3. Corrections are recommended for both maternal serum hCG and AFP before calculating the risk for Down syndrome in black women.