Ultrasound Measurement of the Fetal Adrenal Gland as a Predictor of Spontaneous Preterm Birth.

OBJECTIVE: To estimate whether ultrasound measurement of the fetal adrenal gland remote from delivery in asymptomatic women can accurately predict spontaneous preterm birth. METHODS: We conducted a prospective multicenter observational nested cohort study of asymptomatic nulliparous women with a singleton pregnancy to study adverse pregnancy outcomes. Between 22 0/7 and 30 6/7 weeks of gestation, credentialed ultrasonographers measured the width (width), length (length), and, when able, depth (depth) of the "fetal zone" of the fetal adrenal gland as well as the width (Width), length (Length), and depth (Depth) of the total gland. We used the ratios of each measurement (width/Width, length/Length, and depth/Depth) to control for variation in adrenal size by gestational age. The accuracy of each ratio measurement in predicting spontaneous preterm birth at less than 37 0/7 weeks of gestation and spontaneous preterm birth at less than 34 0/7 weeks of gestation was assessed by receiver operating characteristic curves using area under the curve. RESULTS: Pregnancy outcomes were available for 1,697 women with one or more fetal adrenal gland measurements. Spontaneous preterm birth at less than 37 0/7 weeks of gestation and spontaneous preterm birth at less than 34 0/7 weeks of gestation occurred in 82 (4.8%) and six women (0.4%), respectively. None of the fetal adrenal gland measurements distinguished spontaneous preterm birth from term birth. The areas under the curve (95% confidence intervals) for spontaneous preterm birth at less than 37 0/7 weeks of gestation were 0.51 (0.45-0.58), 0.50 (0.44-0.56), and 0.52 (0.41-0.63) for width/Width, length/Length, and depth/Depth ratios, respectively. The areas under the curve for spontaneous preterm birth at less than 34 0/7 weeks of gestation were 0.52 (0.25-0.79) and 0.55 (0.31-0.79) for width/Width and length/Length ratios, respectively. Additionally, none of the means of the gland measurements were statistically different between those delivering at term and spontaneous at preterm (P>.05). CONCLUSION: Fetal adrenal size, as measured by ultrasonography between 22 0/7 and 30 6/7 weeks of gestation, is not predictive of spontaneous preterm birth in asymptomatic nulliparous women.

Positive cell-free fetal DNA testing for trisomy 13 reveals confined placental mosaicism.

PURPOSE: We report on a case in which cell-free fetal DNA was positive for trisomy 13 most likely due to confined placental mosaicism. Cell-free fetal DNA testing analyzes DNA derived from placental trophoblast cells and can lead to incorrect results that are not representative of the fetus. METHODS: We sought to confirm commercial cell-free fetal DNA testing results by chorionic villus sampling and amniocentesis. These results were followed up by postnatal chromosome analysis of cord blood and placental tissue. RESULTS: First-trimester cell-free fetal DNA test results were positive for trisomy 13. Cytogenetic analysis of chorionic villus sampling yielded a mosaic karyotype of 47,XY,+13[10]/46,XY[12]. G-banded analysis of amniotic fluid was normal, 46,XY. Postnatal cytogenetic analysis of cord blood was normal. Karyotyping of tissues from four quadrants of the placenta demonstrated mosaicism for trisomy 13 in two of the quadrants and a normal karyotype in the other two. CONCLUSION: Our case illustrates several important aspects of this new testing methodology: that cell-free fetal DNA may not be representative of the fetal karyotype; that follow-up with diagnostic testing of chorionic villus sampling and/or amniotic fluid for abnormal test results should be performed; and that pretest counseling regarding the full benefits, limitations, and possible testing outcomes of cell-free fetal DNA screening is important.

Genomic loss of imprinting in first-trimester human placenta.

OBJECTIVE: The purpose of this study was to investigate imprinting patterns in first-trimester human placentas. STUDY DESIGN: Using samples of 17 first-trimester and 14 term placentas from uncomplicated pregnancies, we assessed loss of imprinting (LOI) at the RNA level in a panel of 14 genes that are known to be imprinted in the placenta with the use of a quantitative allele-specific reverse transcriptase polymerase chain reaction analysis of those genes that contained readout single nucleotide polymorphisms in their transcripts. RESULTS: There is significant LOI (ie, biallelic expression) in all 14 genes in first-trimester placentas. LOI was more variable and generally at lower levels at term. Although there is little difference in gene expression, the level of LOI is higher in the first-trimester placentas, compared with term placentas. CONCLUSION: Genomic imprinting appears to be a dynamic maturational process across gestation in human placenta. In contrast with prevailing theories, epigenetic imprints may continue to evolve past 12 weeks of gestation.