Risk of abnormal triple screen for Down syndrome is significantly higher in patients with female fetuses.

Previous studies have shown that mid-trimester maternal serum alpha-fetoprotein (AFP) levels are significantly higher and human chorionic gonadotrophin (hCG) levels significantly lower in women with male compared with female fetuses. We have evaluated whether triple-screen criteria are more likely to identify women with female fetuses as at risk for Down syndrome. From the Georgetown University genetics database we obtained the absolute values and corresponding multiples of the median (MoM) for AFP, hCG and unconjugated oestriol (uE3) in singleton gestations for the period database November 1992 July 1996. A Down syndrome risk of 1/270 or greater at mid-trimester was considered as high risk. A total of 977 patients with triple screen and outcome information were identified, including 502 female and 475 male fetuses. Patients with female fetuses were significantly more likely to have lower serum AFP (p=0.003) and a positive triple screen for Down syndrome (72 (14 per cent) versus 45 (9 per cent), p<0.02) than those with male fetuses. The gestational age at triple screen, maternal serum hCG and uE3, race and diabetes were not significantly different between the two groups. Since Down syndrome is less common in female than male fetuses, and the rates of female and male Down syndrome fetuses detected by triple screen and subsequent amniocentesis are not significantly different, the excess of positive mid-trimester maternal serum triple screen in women with female fetuses is likely due to false-positive results.

Second-trimester amniotic fluid or maternal serum interleukin-10 levels and small for gestational age neonates.

OBJECTIVE: To evaluate if interleukin-10 levels in either early second-trimester amniotic fluid (AF) or maternal serum can be utilized as a predictor of the subsequent occurrence of small for gestational age (SGA) infants after controlling for gestational age at delivery. METHODS: We identified patients who underwent genetic amniocentesis for standard genetic indications or maternal blood sampling for maternal serum alpha-fetoprotein (MSAFP)/triple screen between January 1992 and February 1995 with available follow-up delivery data. Small for gestational age was defined as birth weight less than the tenth percentile for gestational age. Control patients were matched for gestational age at delivery, maternal age, race, and parity with at least two controls for each study patient. We excluded patients with maternal immune disease, chronic hypertension, diabetes, asthma, congenital heart disease, multiple gestation, and fetuses with structural or chromosomal anomalies. Second-trimester AF and serum samples were assayed for interleukin-10. Potential confounding variables considered were MSAFP level, smoking history, pregnancy-induced hypertension, and neonatal gender. The interleukin-10 levels were normalized using natural log transformation for statistical analysis. Statistical analysis included chi 2, Fisher exact test, and analysis of variance, with P < .05 considered significant. RESULTS. From the AF data base, 18 patients (6%) delivered SGA neonates and were matched with 46 controls. From the maternal serum data base, 13 patients (7%) delivered SGA neonates and were matched with 45 controls. Neither AF nor maternal serum interleukin-10 levels were significantly different in patients subsequently delivering SGA neonates compared with controls (AF: median 21.0 pg/mL. [range 13.8-27.6] versus 17.5 pg/mL. [range 8.9-362.12], P = .18; serum: median 15.7 pg/mL [range 9.9-73.5] versus 18.7 pg/mL [range 9.7-71.7], P = .60, respectively). No significant differences were identified in gestational age at sampling, maternal smoking history, pregnancy-induced hypertension, or elevated MSAFP in patients delivering SGA neonates compared with controls (P > .05 for each). As expected, birth weight was significantly lower in patients delivering SGA neonates compared with controls (P < .001). CONCLUSION: Second-trimester AF or maternal serum interleukin-10 levels are not predictive of subsequent delivery of SGA infants.