Search PubMed⌕ Search

Biomedical subjects

M Y Divon

Publications and source records attributed to M Y Divon.

At least 19 recordsLinked to original sources
PubMed2002

Maternal pain and anxiety in genetic amniocentesis: expectation versus reality.

OBJECTIVE: To investigate maternal perceptions of both pain and anxiety before and after genetic amniocentesis. STUDY DESIGN: This prospective study of midtrimester, singleton pregnancies was conducted between March 2000 and July 2000. Study variables included patient demographics, medical and obstetric histories, indication for amniocentesis and a description of the source of information used by the patient regarding the procedure and technical degree of difficulty. Maternal pain and anxiety associated with performing amniocentesis were subjectively quantified with the use of the visual analog scale (VAS). Statistical analysis included Wilcoxon signed rank test, anova, and simple and stepwise regression analyses. RESULTS: One hundred and eighty-three women participated in the study. Perception of pain before amniocentesis was significantly higher compared to that expressed immediately after the procedure, with a mean VAS score of 3.7 +/- 2.5 vs. 2.1 +/- 2.0 (P < 0.0001). Similarly, perception of anxiety was significantly greater prior to the procedure, with a mean VAS score of 4.6 +/- 2.8 vs. 2.8 +/- 2.4 after the amniocentesis (P < 0.0001). Perceptions of pain and anxiety were significantly and positively correlated to each other both before and after the procedure (P < 0.0001). History of a prior amniocentesis was the only variable associated with reducing expected pain and anxiety (negative correlation, P < 0.001), whereas the technical degree of difficulty was the only significant variable impacting on the actual pain and anxiety (positive correlation, P < 0.005). CONCLUSIONS: Preamniocentesis counseling should emphasize the fact that, for most women, the actual pain and anxiety experienced during the procedure are significantly lower than expected. In fact, on a scale of 0-10, the mean level of pain was only 2.1, with a slightly higher mean level of anxiety.

Adult↗
PubMed2002

The association between fetal and maternal sleep patterns in third-trimester pregnancies.

OBJECTIVE: We sought to investigate the association between fetal heart rate and maternal electroencephalogram patterns during overnight sleep. STUDY DESIGN: Data were collected prospectively between December 1, 1999, and June 30, 2001. Initially, the participating patients were asked to complete a 66-question survey for the assessment of maternal perception of sleep quality that was referred to as the sleep disturbance score: a continuous score from 0 (no evidence of sleep disturbance) to 110 (extreme sleep disturbance). Second, a subgroup of patients was monitored overnight by concomitant fetal heart rate and maternal electroencephalogram tracings. Statistical analysis included the Student t test, chi2 test, logistic regression, and Cramer's V contingency correlation. RESULTS: One hundred two singleton pregnancies formed the study population. The mean sleep disturbance score was 26.7 +/- 9.9. Maternal age was the only variable that correlated with sleep disturbance score. A subgroup of 11 patients was studied overnight. A significant correlation between active fetal sleep and maternal wakefulness was demonstrated in 6 patients. The mean sleep disturbance score for these patients was significantly higher than for patients without such correlation (P =.04). CONCLUSION: This study establishes an association between fetal activity and maternal wakefulness, which explains many of the maternal awakenings during sleep in the third trimester.

Adult↗
PubMed2002

Nucleated red blood cells in human fetal scalp capillary blood samples: a feasibility study.

OBJECTIVE: Elevated umbilical cord nucleated red blood cell (NRBC) counts have been suggested as a predictor of adverse perinatal outcome. We sought to evaluate the feasibility of obtaining fetal scalp capillary blood NRBC counts during labor and to assess their correlation with umbilical cord NRBC counts. METHODS: Fetal scalp capillary blood specimens were prospectively collected in laboring patients who underwent scalp sampling because of the presence of an abnormal fetal heart rate pattern. Matched umbilical cord blood samples were collected immediately after birth. Outcome measures were the feasibility of obtaining fetal scalp NRBC counts and their correlation with umbilical cord NRBC counts. RESULTS: Thirteen term singleton pregnancies formed the study population. In four patients, fetal scalp capillary blood sampling was performed twice. Of the attempts to evaluate fetal scalp capillary samples for NRBC counts, 16 out of 17 (94.1%) were successful. The mean fetal scalp capillary blood NRBC count per 100 white blood cells was 12.6 +/- 7.6 (+/- SD). Umbilical cord mixed, venous and arterial NRBC counts were 15.5 +/- 8.8, 13.4 +/- 10.7 and 12.6 +/- 10.7, with p = 0.09, p = 0.59 and p = 0.68, respectively, when compared to the corresponding scalp sample. The Spearman rank correlation between fetal scalp capillary samples and umbilical cord mixed, venous and arterial NRBC counts were r = 0.86, r = 0.92 and r = 0.95, respectively, with all p values < 0.001. CONCLUSION: Previous studies have established the clinical utility of umbilical cord NRBC counts. Our study demonstrated that it was possible to obtain NRBC counts from a fetal scalp capillary sample and that these counts correlated highly with umbilical cord NRBC counts. Future studies are needed to evaluate fetal scalp NRBC counts as a predictor of perinatal outcome.

Blood Specimen Collection↗
PubMed2001

Non-reassuring fetal status in the prolonged pregnancy: the impact of fetal weight.

OBJECTIVE: To evaluate the incidence of abnormal fetal findings and Cesarean delivery for non-reassuring fetal status as a function of birth weight in the uncomplicated prolonged pregnancy. METHODS: Seven hundred and ninety-two patients at or beyond 41 weeks' gestation were managed expectantly. Population-specific birth-weight percentiles were calculated. Fetuses were retrospectively categorized as small (birth weight < 10th percentile), average (10th percentile < or = birth weight < or = 90th percentile) or large (birth weight > 90th percentile). The incidences of abnormal antepartum fetal testing results (i.e. oligohydramnios and/or abnormal non-stress testing) and Cesarean delivery for intrapartum non-reassuring fetal status were calculated for these three birth-weight categories. RESULTS: There was a significant inverse relationship between the incidence of abnormal fetal testing and birth-weight category (36%, 14% and 9% for small, average and large fetuses, respectively, P < 0.001). Small fetuses were more likely to require a Cesarean delivery for non-reassuring fetal status during labor than were all other fetuses (12.3% vs. 5.3%, P = 0.024). CONCLUSIONS: The frequency of oligohydramnios and abnormal non-stress testing is inversely related to birth weight in the expectantly managed prolonged pregnancy. In addition, small fetuses born at or beyond 41 weeks' gestation have an increased rate of Cesarean delivery for intrapartum non-reassuring fetal status.

Birth Weight↗
PubMed2001

Umbilical artery Doppler velocimetry--an update.

Doppler ultrasonography was introduced into clinical obstetric practice over 20 years ago. It is also accepted that a variety of common obstetrical complications such as preeclampsia and intrauterine growth restriction have their origin in abnormal development of the placental vasculature and this could be reflected in abnormal Doppler velocimetry. Doppler velocimetry of the umbilical artery has been the subject of multiple clinical studies but results have often been disputed due to differences in study populations and methodologies. In recent years, meta-analysis of randomized clinical trials have shown that incorporation of Doppler velocimetry into clinical practice will reduce perinatal mortality in high-risk patients. This article reviews the data of the meta-analyses as it pertains to the management of high-risk pregnant patients.

Blood Flow Velocity↗
PubMed2001

The impact of maternal ketonuria on fetal test results in the setting of postterm pregnancy.

OBJECTIVE: The aim of this study was to determine whether ketonuria, a commonly assessed urinary marker of maternal starvation and dehydration, is associated with abnormal fetal test results in the setting of postterm pregnancy. STUDY DESIGN: During a 4-year period (January 1993-December 1996), a total of 3655 visits for antepartum maternal-fetal testing of postterm pregnancies (> or =41 weeks' gestation) occurred at our institution. Maternal assessment included vital signs and urinalysis. The presence and degree of maternal ketonuria was correlated against abnormal results of fetal heart rate tests, nonstress tests, amniotic fluid index measurements, and biophysical profile scores performed on the same day. RESULTS: There were 3601 encounters suitable for inclusion in the study. Clinically detectable ketonuria occurred in 10.9% of the patients studied. Patients with clinically detectable ketonuria were at increased risk relative to patients without ketonuria for abnormal outcomes during postterm testing, including the presence of oligohydramnios (24% vs. 9.3%; P<.0001 ), nonreactive nonstress tests (6.2% vs. 2.15%; P<.0001), and fetal heart rate decelerations (14% vs 9.2%; P =.0039 ). CONCLUSION: Maternal ketonuria among patients with postterm pregnancy was associated with a >2-fold increase in the occurrence of oligohydramnios, a 3-fold increase in nonreactive nonstress tests, and a significant increase in fetal heart rate decelerations. Further studies are required to evaluate the potential benefits of treating ketonuria before fetal testing.

Adult↗
PubMed2000

Nucleated red blood cell count in the differentiation of fetuses with pathologic growth restriction from healthy small-for-gestational-age fetuses.

OBJECTIVE: The purpose of this study was to evaluate the utility of the neonatal nucleated red blood cell count in differentiating the fetus with growth restriction from the small but otherwise healthy fetus. STUDY DESIGN: Perinatal outcomes were evaluated prospectively for all neonates admitted to the neonatal intensive care unit in 1997. Nonanomalous neonates with normal phenotype and a complete blood cell count performed within the first 6 hours after birth were included in the study. All neonates with birth weights lower than the 10th percentile for gestational age were considered small for gestational age. Neonates were divided into four groups: small-for-gestational-age neonates with elevated nucleated red blood cell counts, appropriately grown neonates with elevated nucleated red blood cell counts, small-for-gestational-age neonates with normal nucleated red blood cell counts, and appropriately grown neonates with normal nucleated red blood cell counts. Analysis of variance, chi(2) tests, and stepwise regression were used for statistical analysis. RESULTS: Two hundred thirty-seven neonates met the inclusion criteria. Forty-three were small for gestational age. Small-for-gestational-age neonates with high nucleated red blood cell counts had significantly lower umbilical artery pH and were more likely to require mechanical ventilation or blood pressure support agents. Subgroup analysis demonstrated that small-for-gestational-age neonates with elevated nucleated red blood cell counts had significantly more adverse outcomes than did small-for-gestational-age neonates with normal nucleated red blood cell counts. Outcomes of small-for-gestational-age neonates with normal nucleated red blood cell counts were essentially identical to those of appropriately grown neonates. CONCLUSION: An elevated nucleated red blood cell count may distinguish the fetus with growth restriction from the small but healthy fetus.

Erythroblasts↗
PubMed1999

Receiver operating characteristic curves of ultrasonographic estimates of fetal weight for prediction of fetal growth restriction in prolonged pregnancies.

OBJECTIVE: Recent studies have documented increased perinatal morbidity and mortality rates in the growth-restricted postterm fetus. Our purpose was to evaluate the receiver operating characteristic curve of ultrasonographically estimated fetal weight as a predictor of fetal growth restriction in prolonged pregnancies. STUDY DESIGN: Fetal weight was estimated ultrasonographically within 9 days of delivery (mode 1 day) in members of a cohort of 410 patients with prolonged pregnancies (>41 weeks). Estimated fetal weights were compared with birth weights in receiver operating characteristic curve analysis. RESULTS: The areas under the receiver operating characteristic curves for predicting birth weights <10th percentile (3125 g in this population) and <5th percentile (2930 g in this population) were 0.89 and 0.96, respectively. Both areas were significantly different from an area indicating a useless test. The estimated fetal weight values corresponding to the inflection points for the receiver operating characteristic curves predicting birth weights <10th percentile and <5th percentile were 3370 and 3200 g, respectively. With estimated fetal weight at less than these test cutoff values, the relative risks for a fetus to have a birth weight <10th percentile or <5th percentile were 14.6 (95% confidence interval, 6.25-33.8) and 89.8 (95% confidence interval, 12.1-665), respectively. Analysis of the receiver operating characteristic curves resulted in improved test characteristics relative to using the actual 10th and 5th birth weight percentiles as cutoff values for estimated fetal weight (relative risk of 14.6 vs 9.5 and 89.8 vs 26.0, respectively). CONCLUSIONS: Ultrasonographic estimation of fetal weight is a useful test for predicting fetal growth restriction in prolonged pregnancies. Future studies should evaluate whether intervention on the basis of this identification results in improved perinatal outcome.

Birth Weight↗
PubMed1999

Transplantation of CD34 human cells into mice with severe combined immunodeficiency results in functional T cells 4 weeks after transplantation.

OBJECTIVE: Our purpose was to determine whether transplantation of fetal human CD34(+) cells into mice with severe combined immunodeficiency results in functional T cells. STUDY DESIGN: The cells used in this study were isolated from fetal human liver tissue obtained after elective termination of normal 18- to 24-week pregnancies. Women with medical conditions that could confound the outcome were excluded. Cells were labeled with fluorochrome-conjugated antibodies that recognized CD34 or other cell surface antigens. The cells were then sorted with the use of a fluorescein-activated cell sorter. The human sorted cells were injected intraperitoneally in mice with severe combined immunodeficiency. Four groups of mice were studied: group 1, injected with 10(5) CD34(+) cells (n = 17); group 2, injected with 10(5) CD34(-) cells (n = 14); group 3, injected with 10(6) unsorted cells (n = 19); and group 4, sham-injected with phosphate-buffered saline solution as controls (n = 14). At 1, 2, and 4 weeks after transplantation, the peripheral blood monocytes of the study mice were analyzed for functional T cells. Aliquots of cells (10(5)) were incubated for 48 hours with 0, 5, 10, and 20 micrograms of phytohemagglutinin. Thereafter the cells were treated with 1 microCi of tritiated thymidine. Subsequently the incorporation of tritiated thymidine was determined by liquid scintillation counting. RESULTS: Cells from mice transplanted with either unsorted cells, sorted CD34(+) cells, or CD34(-) cells showed a response to phytohemagglutinin that varied with time and with the mitogen concentration. Even though unsorted fetal human liver cells had a maximal response at 2 weeks, this posttransplantation response was not statistically significant. CD34(+) cell response to phytohemagglutinin was significant at 4 weeks after transplantation. CD34(-) cells also had a peripheral blood cell response at 4 weeks after transplantation; however, this response was not statistically significant. In addition, all mice transplanted with fetal human liver cells had some functional T cells at 4 weeks; however, this response was statistically significant only for CD34(+) cells. CONCLUSION: Transplantation of either sorted CD34 (positive or negative) cells or unsorted fetal human liver cell preparations into mice with severe combined immunodeficiency results in functional T cells. However, only the mice with transplanted CD34(+) cells demonstrated a statistically significant response.

Animals↗
PubMed1998

Fetal and neonatal mortality in the postterm pregnancy: the impact of gestational age and fetal growth restriction.

OBJECTIVE: Our purpose was to examine the impact of gestational age and fetal growth restriction on fetal and neonatal mortality rates in the postterm pregnancy. STUDY DESIGN: All deliveries occurring in Sweden between Jan. 1, 1987, and Dec. 31, 1992, were evaluated for participation in this study. Data were derived from the National Swedish Medical Birth Registry. Pregnancies were selected for inclusion in the study on the basis of the following criteria: (1) singleton pregnancy, (2) reliable dates, (3) gestational age > or = 40 weeks, and (4) maternal age 15 to 44 years. Fetal growth restriction was defined as birth weight <2 SD below the mean for gestational age. A total of 181,524 pregnancies met the inclusion criteria and formed the study population. Fetal and neonatal mortalities at 40 weeks' gestation were used as reference levels. Logistic regression analysis was used to estimate the independent effects of gestational age and fetal growth restriction on fetal and neonatal mortality rates. RESULTS: A significant rise in the odds ratio for fetal death was detected from 41 weeks' gestation and on (odds ratios 1.5, 1.8, and 2.9 at 41, 42, and 43 weeks, respectively). Odds ratios for neonatal mortality did not demonstrate a significant gestational age dependency. Fetal growth restriction was associated with significantly higher odds ratios for both fetal and neonatal mortality rates at every gestational age examined (with odds ratios ranging from 7.1 to 10.0 for fetal death and from 3.4 to 9.4 for neonatal death). CONCLUSIONS: Postterm pregnancies have long been considered to be at high risk for adverse perinatal outcome. This study documents a small but significant increase in fetal mortality in accurately dated pregnancies that extend beyond 41 weeks of gestation. This study also demonstrates that fetal growth restriction is independently associated with increased perinatal mortality in these pregnancies.

Adolescent↗
PubMed1998

Prenatal sonographic findings associated with sporadic subcortical nodular heterotopia.

BACKGROUND: Subcortical nodular heterotopia is a neuronal migration disorder of uncertain etiology. This disorder occurs primarily in females and has a familial X-linked dominant inheritance pattern. The predominant symptom associated with heterotopia is seizures. CASE: At 23 weeks' gestation, prenatal sonography disclosed an isoechoic supratentorial intracranial mass causing right-sided shift of midline structures and compression of the contralateral cerebral ventricle. Serial ultrasound examinations of this mass were significant for the absence of invasion into surrounding structures, gross enlargement of cranial biometric parameters, and hydrocephalus and hydrops fetalis. Neonatal magnetic resonance imaging findings were consistent with gray matter heterotopia and were confirmed as such by brain biopsy. CONCLUSION: Subcortical nodular heterotopia manifested unique prenatal sonographic findings. This case suggests the possibility of prenatal diagnosis in families at risk for this lesion.

Adult↗
PubMed1998

Fetal growth restriction at term: myth or reality?

OBJECTIVE: To evaluate the morbidity and mortality associated with the small for gestational age (SGA) fetus born at term to an otherwise uncomplicated pregnancy. METHODS: Small for gestational age, singleton newborns (birth weight below the tenth percentile for gestational age) born at 37-42 weeks' gestation were identified by medical record discharge coding. We excluded gestations complicated by structural or chromosomal abnormalities, maternal diabetes mellitus, preeclampsia, chronic hypertension, asthma, or renal, endocrine, or autoimmune disease. Three low-risk, appropriate for gestational age (AGA) fetuses, matched for gestational age at delivery, were selected randomly for each SGA fetus and served as controls. Maternal and neonatal data were abstracted via medical record review. Statistical analysis included chi2 Fisher exact test, and analysis of variance. RESULTS: There were 67 newborns in the study group and 201 in the control group. There were no fetal or neonatal deaths in any of these cases. The maternal age at delivery, prepregnancy weight, race, smoking status, weight gain during pregnancy, and neonatal gender did not statistically differ between the two groups. Compared with AGA infants, a larger proportion of SGA newborns had low 1-minute Apgar scores and SGA newborns were more likely to be admitted to the neonatal intensive care unit, and have respiratory distress, hypoglycemia, thrombocytopenia, and hyperbilirubinemia. They were also significantly more likely to be delivered by cesarean. CONCLUSION: The SGA newborn from an uncomplicated pregnancy delivered at term has increased neonatal morbidity compared with its AGA counterpart. These results dispute the notion that term growth restriction is a benign condition.

Adult↗
PubMed1998

Transvaginal sonography of the forewaters in the assessment of amniotic fluid volume in patients with oligohydramnios.

OBJECTIVE: To determine whether the forewaters should be considered in the assessment of amniotic fluid (AF) volume in patients beyond 37 weeks' gestation. METHODS: Sixty patients were prospectively studied and designated as having oligohydramnios or normal AF volume based upon on the standard four-quadrant AF index (AFI) of < or = 5 cm or > 5 cm, respectively. The distance between the internal os and the fetal head was measured transvaginally. This measurement was first added to the standard AFI and subsequently interchanged with the lowest of the two lower abdominal quadrant measurements. Statistical analysis included Student's t-test with p < 0.05 considered significant. RESULTS: Thirty patients were classified as oligohydramnios and 30 normal AF volume. The two subgroups did not differ as to maternal age, parity, gestational age at sonographic examination, incidence of meconium-stained amniotic fluid or 5-min Apgar scores < 7, or birth weight. No significant difference was noted between the mean forewaters measurement of patients with oligohydramnios and controls (0.2 +/- 0.1 and 0.4 +/- 0.1 cm, respectively). In patients with oligohydramnios, there was no significant difference between the standard AFI and the AF volume with the forewaters in each of the methods assessed (2.7 +/- 0.3, 2.9 +/- 0.3, and 2.7 +/- 0.3 cm, respectively). CONCLUSION: We conclude that various permutations of the AFI, which include sonographic assessment of the forewaters, do not impact on the diagnosis of oligohydramnios.

Abdomen↗
PubMed1998

Uncomplicated baseline fetal tachycardia or bradycardia in postterm pregnancies and perinatal outcome.

OBJECTIVE: to assess perinatal outcome in post-term pregnancies in which fetal heart rate (FHR) monitoring revealed either uncomplicated baseline fetal tachycardia (> or = 160 bpm) or fetal bradycardia (< or = 120 bpm). STUDY DESIGN: We performed a case-control study of patients who underwent fetal assessment between July 1989 and June 1995, as part of post-term evaluation. Inclusion criteria consisted of nonlaboring afebrile patients with singleton post-term pregnancies > or = 41 weeks of gestation by strict dating criteria (last menstrual period consistent with ultrasound biometric parameters obtained prior to 20 weeks' gestation), normal fetal anatomy, intact membranes, and reactive nonstress test with no evidence of chorioamnionitis. Patients with fetal tachy or brady arrhythmias, FHR decelerations, or loss of short-term beat-to-beat variability were excluded. Baseline FHR was recorded retrospectively by an observer blinded to maternal and neonatal clinical outcome. For each case of uncomplicated baseline fetal tachycardia (> or = 160 bpm) or bradycardia (< or = 120 bpm), either two or three control cases (matched for maternal age and parity), with FHR > 120 bpm and < 160 bpm, were identified. Outcome variables assessed included: incidence of cesarean delivery, nuchal cord at delivery, meconium-stained amniotic fluid (AF), 5-min Apgar score < 7, fetal growth restriction (< 10th percentile for 41 weeks' gestation), meconium aspiration syndrome, and neonatal intensive care unit (NICU) admission. Statistical analysis included two-tailed t-test and chi2 test when appropriate, with p < 0.05 considered significant throughout. RESULTS: During the study period 1390 post-term patients (6.81% of the general population) were assessed. Of these, 31 (2.23%) fetuses exhibited baseline FHR > or = 160 bpm, and 76 fetuses (5.46%) exhibited baseline FHR < or = 120 bpm. No significant differences were noted in the incidence of cesarean delivery, presence of nuchal cord at delivery, meconium-stained AF, 5-min Apgar scores < 7, fetal growth restriction, meconium aspiration syndrome, or the incidence of NICU admissions between the groups of patients with fetal tachycardia, bradycardia, and their respective controls. CONCLUSIONS: Uncomplicated baseline fetal tachycardia or bradycardia in postterm patients are not associated with an increase in the incidence of adverse perinatal outcome.

Bradycardia↗
PubMed1997

Neonatal nucleated red blood cell counts in small-for-gestational age fetuses with abnormal umbilical artery Doppler studies.

OBJECTIVE: The presence of elevated nucleated red blood cell counts in neonatal blood has been associated with fetal hypoxia. We sought to determine whether small-for-gestational-age fetuses with abnormal umbilical artery Doppler velocity waveforms have elevated nucleated red blood cell counts. STUDY DESIGN: Hospital charts of neonates with the discharge diagnosis of small for gestational age (birth weight < 10th percentile) who were delivered between October 1988 and June 1995 were reviewed for antepartum testing, delivery conditions, and neonatal outcome. We studied fetuses who had an umbilical artery systolic/diastolic ratio within 3 days of delivery and a complete blood cell count on the first day of life. Multiple gestations, anomalous fetuses, and infants of diabetic mothers were excluded. Statistical analysis included the Student t test, chi 2 analysis, analysis of variance, and simple and stepwise regression. RESULTS: Fifty-two infants met the inclusion criteria. Those with absent or reversed end-diastolic velocity (n = 19) had significantly greater nucleated red blood cell counts than did those with end-diastolic velocity present (n = 33) (nucleated red blood cells/100 nucleated cells +/- SD: 135.5 +/- 138 vs 17.4 +/- 23.7, p < 0.0001). These infants exhibited significantly longer time intervals for clearance of nucleated red blood cells from their circulation (p < 0.0001). They also had lower birth weights (p < 0.05), lower initial platelet count (p = 0.0006), lower arterial cord blood pH (p < 0.05), higher cord blood base deficit (p < 0.05), and an increased likelihood of cesarean section for "fetal distress" (p < 0.05). Multivariate analysis demonstrated that absent or reversed end-diastolic velocity (p < 0.0001) and low birth weight (p < 0.0001) contributed to the elevation of the nucleated red blood cell count, whereas gestational age at delivery was not a significant contributor. CONCLUSION: We observed significantly greater nucleated red blood cell counts and lower platelet counts in small-for-gestational-age fetuses with abnormal umbilical artery Doppler studies. This may suggest that antenatal thrombotic events lead to an increased placental impedance. Fetal response to this chronic condition may result in an increased nucleated red blood cell count.

Adult↗
PubMed1997

Immunophenotypic characterization of human fetal liver hematopoietic stem cells during the midtrimester of gestation.

OBJECTIVE: Our purpose was to define the extent to which gestational age influences the number of fetal liver cells that coexpress phenotypic markers associated with hematopoietic stem cells and major histocompatibility antigens. STUDY DESIGN: Fetal liver cells from abortuses of 9 to 24 weeks of gestation were studied (n = 61). Low-density nucleated liver cells were isolated on a discontinuous density gradient and subsequently incubated with antibodies that recognize markers of hematopoietic stem cells (i.e., CD33, CD34, CDw90, CD117, and CD123). Human leukocyte antigen class I (A, B, C) and class II (DR) antigens were also determined on these cells. Each sample was analyzed by immunocytochemistry and flow cytometry. Analysis of variance was used for statistical analysis. RESULTS: Of the markers measured, only the percentage of CD123-positive cells increased significantly with gestational age (p < 0.01). The percentage of triple-positive cells (CD34+, CD117+, and CD123+) increased with age but did not reach significance (p = 0.05). Human leukocyte A, B, and C antigens were expressed on all nucleated cells from 9 to 24 weeks of gestation. Human leukocyte DR antigen, however, was expressed only on 50% of these cells. The percentage of cells that expressed both hematopoietic stem cell markers and DR antigen did not vary with gestational age. CONCLUSIONS: From 9 to 24 weeks of gestation the number of human fetal liver hematopoietic stem cells that coexpress major histocompatibility antigens increases with advancing gestational age, largely because the percentage of these cells remains constant while the liver mass increases.

Adolescent↗