Fetus

About: Fetus is a research topic. Over the lifetime, 21567 publications have been published within this topic receiving 646380 citations. The topic is also known as: foetus & fœtus.

Fetal cerebral blood flow redistribution in late gestation: identification of compromise in small fetuses with normal umbilical artery Doppler

Abstract: Objective To evaluate the role of middle cerebral artery Doppler in small fetuses during the late third trimester. Design Prospective observational study of structurally normal fetuses with an estimated fetal weight , 5th percentile for gestation. Perinatal outcome was determined using a structured datasheet sent to each referring obstetrician. Subjects Structurally normal fetuses at 35 or more weeks of gestation referred during a 2-year period to the fetal growth clinic of a regional fetal medicine unit in North London. Fetuses with aneuploidy and/or major structural abnormalities were excluded. Methods Umbilical artery and middle cerebral artery (MCA) Doppler waveforms were recorded and considered abnormal if above 95th or below 5th percentiles, respectively. Amniotic fluid was considered reduced if the maximum vertical cord-free pool was , 2 cm. The placenta was considered mature if the Grannum grade was II or III. The head circumference (HC)/abdominal circumference (AC) ratio was considered abnormal if . 95th percentile for gestation. Fetal growth, amniotic fluid, biophysical profile score and umbilical artery Doppler were used to advise the referring obstetrician about fetal well-being and he/she independently decided both the timing and mode of delivery. Results Forty-seven fetuses fulfilled the entry criteria. Thirty-four (72%) demonstrated normal umbilical artery Doppler waveforms. Sixteen (34%) demonstrated middle cerebral artery redistribution, of which nine (56%) had normal umbilical artery Doppler waveforms. MCA blood flow redistribution was associated with an increased incidence of cesarean delivery and need for neonatal admission. Of all gray-scale parameters, an elevated HC/ AC ratio has the strongest association with MCA blood flow redistribution (15/16 vs. 1/31; P , 0.01). Conclusions MCA Doppler may be a useful tool to assess the health of small fetuses in the late third trimester. Redistribution may occur in the presence of normal umbilical artery Doppler and should be suspected when the HC/AC ratio is elevated.

Echocardiographic Studies of the Human Fetus: Prenatal Diagnosis of Congenital Heart Disease and Cardiac Dysrhythmias

Abstract: During obstetrical ultrasound examinations, 200 M-mode and 35 real-time two-dimensional echocardiographic studies were performed on 180 fetuses of high-risk pregnancies. Fetal gestational ages ranged from 18 to 41 weeks. M-mode "sweeps" demonstrating mitral- and septal-aortic fibrous continuity were obtained in 115 studies. Paradoxic septal motion in 50 fetuses suggested relarive right ventricular volume loading. Congenital cardiac malformations were accurately diagnosed in a 34-week fetus with pulmonary atresia and hypoplastic right ventricle and in a 28-week fetus with a univentricular heart. Congenital complete atrioventricular block was diagnosed in a 28-week fetus and atrial flutter with variable atrioventricular block was diagnosed in a 38-week fetus. The use of echocardiographic studies to evaluate cardiac structure and rhythm in utero assists in counseling prospective parents and in planning postnatal management for their offspring.

Fetal cardiac output, distribution to the placenta and impact of placental compromise

Abstract: Objectives Intrauterine growth restriction is a common clinical problem, but the underlying hemodynamic changes are not well known. Our aim was to determine the normal distribution of fetal cardiac output to the placenta during the second half of pregnancy, and to assess the changes imposed by growth restriction with various degrees of placental compromise. Methods A cross-sectional study of 212 low-risk pregnancies with a gestational age of 18–41 weeks constituted the reference population. A second group of 64 pregnancies with an estimated fetal weight ⩽ 2.5th percentile constituted the study group. Ultrasound measurements of inner diameters and velocities at the fetal left and right ventricular outlets and intra-abdominal umbilical vein were used to determine combined left and right cardiac output (CCO) and the fraction distributed to the placenta. Placental compromise was graded according to umbilical artery waveform: pulsatility index normal, > 97.5th percentile, or absent/reversed end-diastolic velocity. Regression analysis and Z-score (SD-score) statistics were used to establish normal ranges and to compare groups. Results During gestational weeks 18–41 the normal CCO/kg was on average 400 mL/min/kg and the fraction directed to the placenta was on average 32%, while after 32 weeks it was 21%. In intrauterine growth restriction the CCO/kg was not significantly different, but the fraction to the placenta was lower (P < 0.001). This effect was more pronounced in severe placental compromise (P < 0.001). Conclusions Normally, one third of the fetal CCO is distributed to the placenta in most of the second half of pregnancy, and one fifth near term. In placental compromise this fraction is reduced while CCO/kg is maintained at normal levels, signifying an increased recirculation of umbilical blood in the fetal body. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.

Pregnancy induces a fetal antigen-specific maternal T regulatory cell response that contributes to tolerance

Abstract: A fetus is inherently antigenic to its mother and yet is not rejected. The T regulatory (Treg) subset of CD4+ T cells can limit immune responses and has been implicated in maternal tolerance of the fetus. Using virgin inbred mice undergoing a first syngenic pregnancy, in which only the male fetuses are antigenic, we demonstrate a maternal splenocyte proliferative response to the CD4+ T cell restricted epitope of the male antigen (H-Y) in proportion to the fetal antigen load. A portion of the maternal immune response to fetal antigens is Treg in nature. The bystander suppressive function of pregnancy-generated Tregs requires the presence of the fetal antigen, demonstrating their inherent antigen specificity. In vivo targeting of diphtheria toxin to kill Tregs leads to a lower fraction of live male offspring and a selective reduction in mass of the surviving males. Thus, Tregs generated in the context of pregnancy function in an antigen-specific manner to limit the maternal immune response to the fetus in a successful pregnancy.

Uterine and fetal cerebral Doppler predict the outcome of third‐trimester small‐for‐gestational age fetuses with normal umbilical artery Doppler

Abstract: Objective To assess the value of different admission tests in predicting the outcome of small-for-gestational age (SGA) fetuses with normal Doppler waveforms in the umbilical artery. Methods Criteria for admission into this retrospective study included: singleton pregnancy with a birth weight < 10th centile; absence of severe maternal complications; no evidence of fetal anomalies on the sonogram; normal umbilical artery Doppler; and availability of complete follow-up. At the first antenatal sonogram classifying the fetus as SGA, Doppler analysis of the uterine and middle cerebral arteries was performed and amniotic fluid volume was assessed. Outcome variables included adverse perinatal outcome (perinatal death, severe morbidity) and emergency Cesarean section for fetal distress. Results Two hundred and thirty-one pregnancies were included in the study. The mean ± standard deriation birth weight and gestational age at delivery were 2222 ± 502 g and 37.3 ± 2.9 weeks, respectively. In 37 cases (16%), an emergency Cesarean section was performed. There was one intrauterine death and three fetuses delivered by emergency Cesarean section developed severe morbidity. Logistic regression demonstrated that abnormal velocimetry of the uterine arteries and fetal middle cerebral artery were independently correlated with the occurrence of Cesarean section. Conclusions SGA fetuses with normal umbilical artery Doppler waveforms and abnormal uterine arteries and fetal middle cerebral artery waveforms have an increased risk of developing distress and being delivered by emergency Cesarean section. Particularly when both uterine and fetal cerebral waveforms are altered at the same time, the risk is exceedingly high (86%) and delivery as soon as fetal maturity is achieved seems advisable. On the other hand, when both vessels have normal waveforms, the chances of fetal distress are small (4%) and expectant management is the most reasonable choice.