Correlation between first trimester fetal bone length and maternal serum pregnancy-associated plasma protein-A (PAPP-A).

BACKGROUND: Pregnancy-associated plasma protein-A (PAPP-A) is produced by the embryo and placenta during pregnancy, and its maternal serum concentrations are related to subsequent fetal growth. Evidence from animal models and in vitro experiments suggests that PAPP-A is particularly involved in the regulation of bone development. The aim of this study was to assess the correlation between late first trimester fetal bone length and maternal serum levels of PAPP-A. METHODS: In a cross-sectional observational study, ultrasound measurements of fetal long bones and fluorimetric immunoassays for maternal serum PAPP-A were performed in 514 singleton pregnancies at 10-14 weeks of gestation. RESULTS: There were 501 uncomplicated pregnancies. There were significant correlations between PAPP-A values and length of humerus, femur and tibia [r values 0.12 (P = 0.01), 0.11 (P = 0.01) and 0.10 (P = 0.03), respectively]. The association with the length of ulna and foot did not reach statistical significance (r values 0.08 and -0.03, respectively). CONCLUSIONS: Maternal serum PAPP-A levels at 10-14 weeks of gestation are significantly associated with the length of fetal long bones such as humerus, femur and tibia. This provides further evidence that PAPP-A may be involved in the regulation of bone development.

Early vaginal bleeding and first-trimester markers for Down syndrome.

OBJECTIVES: To assess the effect of early vaginal bleeding on first-trimester markers for Down syndrome. METHODS: A retrospective study was conducted on 2330 normal singleton fetuses who underwent first-trimester combined screening for Down syndrome based on ultrasound and maternal serum markers. Fetal nuchal translucency (NT), maternal serum pregnancy-associated plasma protein A (PAPP-A), free beta-hCG and the false-positive rate of the test were compared between pregnancies with (n = 253) and without (n = 2077) a history of early vaginal bleeding. RESULTS: The mean +/- SD log(10) MoM for NT, PAPP-A and free beta-hCG was -0.024 +/- 0.101, 0.007 +/- 0.244, 0.047 +/- 0.273 and -0.011 +/- 0.108, -0.006 +/- 0.223, 0.008 +/- 0.264 in pregnancies with and without a history of early vaginal bleeding, with a p value of 0.07, 0.40 and 0.03 respectively. The false-positive rate was 2.4% and 3.6% (p = 0.33). CONCLUSIONS: An earlier episode of vaginal bleeding is associated with an increase in maternal serum free beta-hCG levels at first-trimester combined screening for Down syndrome. However, this phenomenon is unlikely to significantly affect the false-positive rate of the test.