Equine fetal gender determination from mid- to advanced-gestation by ultrasound

Equine fetal gender can be easily determined by ultrasound between Days 120 and 210. A combination of transrectal and transabdominal ultrasound examinations can visualise fetal sex organs up to 8 months of gestation. Early equine fetal sexing techniques, performed between approximately Days 58 and 70, are aimed at identifying the position of the genital tubercle. A wider diagnostic window, a diagnosis based on several parameters, and the ease of identification of fully developed fetal primary sex organs make gender diagnosis in mid- to advanced-gestation a preferable technique.     

Ultrasonographic features of the mule embryo, fetus and fetal-placental unit

The aim of this study was to establish baseline ultrasound data concerning the mule conceptus during gestation. Ten multiparous Trotter mares were artificially inseminated with chilled semen from an Amiatino jack donkey. Daily transrectal ultrasonography was carried out from the day of ovulation until Day 50 of gestation to determine the following: first detection of the embryonic vesicle (EV), mobility phase, EV diameter, day of EV fixation, changes in EV shape, date of yolk sac regression and embryo crown-rump length. Monthly ultrasonic assessments from Day 50 of gestation to term were carried out. These assessments included an evaluation of fetal well-being and the growth of the mule conceptus, which were monitored using the following variables: cardiac activity, fetal activity and presentation, fetal fluid echogenicity, combined thickness of the utero-placenta unit and fetal orbital and aortic diameter. Mule EV first detection was observed earlier (37% at Day 8) than that observed in the equine pregnancy. EV diameter at first detection was 4.6 ± 1.1 mm. At Day 10, 75% of EVs were detected. EV fixation occurred on Day 17.1 ± 1.1, with a mean EV diameter of 2.5 ± 0.2 cm. EV growth rate was 4.04 mm/day from Days 11 to 16, 0.4 mm/day from Days 16 to 28 and 1.78 mm/day from Days 28 to 45 of pregnancy. The embryo proper was first detected on Day 19.9 ± 1.9 (average length 2.4 ± 1.4 mm), and the embryonic heartbeat was first detected on Day 24 ± 2.4. The fetal carotid pulse was observed at six months of gestation and provided a good means by which to estimate fetal cardiac activity in advanced gestation. The fetal heart rate was recorded from Month 2 of gestation to term. The mean ± SD of the combined uteroplacental thickness was assessed at the cervical-placental junction and at the ventral abdomen in mares between Months 2 and 5 until term, respectively. An abnormal fetal-placental unit and fetal inactivity was observed in association with abortion. Mule-conceptus biometric measurements correlated significantly with the gestational age, and these data were used to predict an unusually large mule fetus, which might result in dystocia. In conclusion, we can assume that early diagnosis of pregnancy failure and assessment of fetal biophysical profile and growth charts could improve the chances of gestation completion in mule-pregnant mares. The early detection of mares at risk for an abnormal pregnancy or delivery may increase the success of prompt treatments, therefore preventing costly emergency procedures and allowing proper obstetrical and neonatal assistance.     

Gestational Dietary Protein Is Associated with Sex Specific Decrease in Blood Flow,Fetal Heart Growth and Post-Natal Blood Pressure of Progeny

Study Overview

The incidence of adverse pregnancy outcomes is higher in pregnancies where the fetus is male. Sex specific differences in feto-placental perfusion indices identified by Doppler assessment have recently been associated with placental insufficiency and fetal growth restriction. This study aims to investigate sex specific differences in placental perfusion and to correlate these changes with fetal growth. It represents the largest comprehensive study under field conditions of uterine hemodynamics in a monotocous species, with a similar long gestation period to the human. Primiparous 14mo heifers in Australia (n=360) and UK (n=180) were either individually or group fed, respectively, diets with differing protein content (18, 14, 10 or 7% crude protein (CP)) from 60d prior to 98 days post conception (dpc). Fetuses and placentae were excised at 98dpc (n = 48). Fetal development an median uterine artery blood flow were assessed monthly from 36dpc until term using B-mode and Doppler ultrasonography. MUA blood flow to the male feto-placental unit increased in early pregnancy associated with increased fetal growth. Protein restriction before and shortly after conception (-60d up to 23dpc) increased MUA diameter and indices of velocity during late pregnancy, reduced fetal heart weight in the female fetus and increased heart rate at birth, but decreased systolic blood pressure at six months of age.

Conclusion and Significance

Sex specific differences both in feto-placental Doppler perfusion indices and response of these indices to dietary perturbations were observed. Further, maternal diet affected development of fetal cardiovascular system associated with altered fetal haemodynamics in utero, with such effects having a sex bias. The results from this study provide further insight into the gender specific circulatory differences present in the fetal period and developing cardiovascular system.     

Three-dimensional ultrasound imaging of the equine fetus

The objective was to assess the optimal procedure for real-time, three-dimensional (3D) ultrasound (US) imaging for assessing the equine fetus during the first half of gestation and the possibility of using 3D US imaging of the equine fetus in clinical applications. Seventeen pregnant mares were examined by 3D US between Days 35 and 180 of gestation. Abdominal and endo-vaginal real-time 3D transducers used in human medicine were used for transrectal and transvaginal examinations, respectively. Images were recorded by both 3D stationary and real-time movies. In a comparison of four methods, transrectal examination with a bulb-shaped abdominal 3D transducer enabled the equine fetus to be clearly visualized, and did not require sedation of the mare. Therefore, this approach was the most suitable procedure for examining equine fetuses during the first half of gestation. Each scan required only a few seconds and an entire examination took <10 min in total. The 3D volume image was easy to restore after the examination and could be rotated to any angle the examiner desired. Fetal surface structures, including the head, body, limbs, and genital tubercle, were observed as 3D images which enabled fetal development to be characterized. For early (Days 60-70), but not later (Days 90-150) periods, 3D ultrasonography was not able to evaluate fetal structure in detail as well as conventional 2D ultrasonography. In conclusion, 3D ultrasonography of the equine fetus was a valuable adjunct to 2D ultrasonography and a convenient modality for more detailed assessment of fetal structures.     

Fetal blood sampling in baboons (Papio spp.): Important procedural aspects and literature review

Background  The baboons ( Papio cynocephalus ) have similarities with human placentation and fetal development. Fetal blood sampling allows investigators to assess fetal condition at a specific point in gestation as well as transplacental transfer of medications. Unfortunately, assessing fetal status during gestation has been difficult and fetal instrumentation associated with high rate of pregnancy loss. Our objectives are to describe the technique of ultrasound guided cordocentesis (UGC) in baboons, report post-procedural outcomes, and review existing publications.
Methods  This is a procedural paper describing the technique of UGC in baboons. After confirming pregnancy and gestational age via ultrasound, animals participating in approved research protocols that required fetal assessment underwent UGC.
Results  We successfully performed UGC in four animals (five samples) using this technique. Animals were sampled in the second and third trimesters with fetal blood sampling achieved by sampling a free cord loop, placental cord insertion site or the intrahepatic umbilical vein. All procedures were without complication and these animals delivered at term.
Conclusions  Ultrasound guided fetal umbilical cord venipuncture is a useful and safe technique to sample the fetal circulation with minimal risk to the fetus or mother. We believe this technique could be used for repeated fetal venous blood sampling in the baboons.     

Maternal and feto-placental prostanoid responses to a single course of antenatal betamethasone

We tested the hypothesis that antenatal betamethasone alters prostanoid levels in the maternal and feto-placental compartments. Forty-three singleton pregnancies were studied. Group I were women treated with a single course of antenatal betamethasone and who delivered <37 weeks gestation; Group II were untreated women who delivered <37 weeks; and Group III were untreated women who delivered >38 weeks. Maternal and mixed cord blood; and placental samples were collected at delivery and analyzed for PGE2, PGF(2alpha), 6-ketoPGF(1alpha), and TxB2 levels. Antenatal betamethasone decreased maternal PGE2 levels with concomitant increases in the feto-placental compartment. Umbilical cord TxB2 levels in the treated group were significantly lower than the non-treated pre-term and term groups resulting in a higher 6-ketoPGF(1alpha):TxB2 ratio. Considering the regulatory role of PGE2 and PGI2 in fetal lung development and neonatal transition homeostasis, these results suggest a mechanism, at least in part, for the beneficial effects of antenatal steroids on fetal lung maturation and neonatal cardio-pulmonary homeostasis at birth.     

Estimation of mouse fetal weight by ultrasonography: application from clinic to laboratory

Ultrasonographic assessment of fetal growth to estimate fetal weight has been widely used in clinical obstetrics but not in laboratory mice. Even though it is important to assess fetal growth abnormalities for gene-targeting studies using mice, there have been no reports of accurately estimated fetal weight using fetal biometric parameters in mice. The aim of this study was to establish an accurate mouse formula using fetal biometric parameters under ultrasound imaging. Using a high-frequency ultrasound system with a 40 MHz transducer, we measured 293 fetuses of biparietal diameter and mean abdominal diameter from day 12.5 postcoitus (p.c.) until day 18.5 p.c every day. Thirteen algorithms for humans based on head and/or abdominal measurements were assessed. We established an accurate formula based on measurement of the abdomen in Jcl:ICR mice to investigate gestational complications, such as intrauterine growth restriction.     

Sex Specific Differences in Fetal Middle Cerebral Artery and Umbilical Venous Doppler

Background

The incidence of several adverse pregnancy outcomes including fetal growth restriction are higher in pregnancies where the fetus is male, leading to suggestions that placental insufficiency is more common in these fetuses. Placental insufficiency associated with fetal growth restriction may be identified by multi-vessel Doppler assessment, but little evidence exists regarding sex specific differences in these Doppler indices or placental function. This study aims to investigate sex specific differences in fetal and placental perfusion and to correlate these changes with intra-partum outcome.

Methods and Findings

This is a prospective cohort study. We measured Doppler indices of 388 term pregnancies immediately prior to the onset of active labour (≤3 cm dilatation). Fetal sex was unknown at the time of the ultrasound assessment. Information from the ultrasound scan was not made available to clinical staff. Case notes and electronic records were reviewed following delivery. We report significantly lower Middle Cerebral artery pulsatility index (1.34 vs. 1.43, p = 0.004), Middle Cerebral artery peak velocity (53.47 cm/s vs. 58.10 cm/s, p = <0.001), and Umbilical venous flow/kg (56 ml/min/kg vs. 61 ml/min/kg, p = 0.02) in male fetuses. These differences however, were not associated with significant differences in intra-partum outcome.

Conclusion

Sex specific differences in feto-placental perfusion indices exist. Whilst the physiological relevance of these is currently unknown, the identification of these differences adds to our knowledge of the physiology of male and female fetuses in utero. A number of disease processes have now been shown to have an association with changes in fetal haemodynamics in-utero, as well as having a sex bias, making further investigation of the sex specific differences present during fetal life important. Whilst the clinical application of these findings is currently limited, the results from this study do provide further insight into the gender specific circulatory differences present in the fetal period.     

The effects of maternal undernutrition on maternal and fetal serum insulin-like growth factors, thyroid hormones and cortisol in the guinea pig.

The insulin-like growth factors (IGF-I and -II) are potential mediators of the effects of maternal undernutrition on fetal growth and muscle development. The effects of a 40% reduction in maternal feed intake on serum levels of the IGFs, the thyroid hormones and cortisol, were investigated for the last two trimesters (day 25 to birth). This level of undernutrition is known to cause a 35% reduction in fetal and placental weights, and a 20-25% reduction in muscle fibre number. Maternal IGF-I level was greater than non-pregnant levels on day 25 gestation, in both control and restricted dams, and declined with gestational age. The increase in IGF-I level in the 40% restricted group was approximately two-thirds that of control animals. Fetal serum IGF-I was also reduced in undernourished fetuses throughout gestation. Maternal IGF-II did not change with gestational age and was unaffected by undernutrition. Fetal IGF-II reached a peak at day 55 of gestation, this peak was greatly diminished by maternal feed restriction. Both IGF-I and IGF-II tended to be related to fetal, placental and muscle weights at day 65 of gestation. Thyroid hormone concentration declined in maternal serum and increased in fetal serum with increasing gestational age. Levels were not significantly affected by undernutrition. Both triiodothyronine (T3) and thyroxine (T4) were correlated with IGF-I in maternal serum (P < 0.05), but not in fetal serum. Cortisol levels were elevated by undernutrition in both maternal and fetal serum, and increased with gestational age. Cortisol was inversely correlated with serum IGF-I in both maternal and fetal serum. Maternal serum IGF-I may mediate the effects of undernutrition on fetal growth by affecting the growth and establishment of the feto-placental unit in mid-gestation. Fetal IGF-I may mediate the effects on muscle growth, whereas IGF-II seems to be related to hepatic glycogen deposition. Cortisol may play a role via its effect on the IGFs, but the thyroid hormones are unlikely to be important until the late gestation/early postnatal period.     

Plasma concentrations of pregnancy-associated glycoprotein-1 (PAG-1) in high producing dairy cows suffering early fetal loss during the warm season

The present study was designed to establish whether plasma pregnancy-associated glycoprotein-1 (PAG-1) measurements during the early fetal period can be associated with early fetal loss. Blood samples were obtained and ultrasound controls performed on days 35, 42, 49, 56, and 63 of gestation or until pregnancy loss from 98 lactating dairy cows. Radioimmunoassay systems were used to determine PAG-1 and progesterone concentrations. Of the 98 pregnancies investigated 18 (18.4%) suffered early fetal loss: 15 (18.5%) in cows carrying singletons, and 3 (16.7%) in twin pregnancies. In cows suffering pregnancy loss, all living embryos registered on day 35 seemed normal in size and development in all weekly ultrasound controls before fetal expulsion. Using analysis of variance, plasma PAG-1 and progesterone values were not different between no loss and fetal loss groups for every gestation period. Based on the odds ratio, and considering only PAG-1 values obtained on day 35 of gestation, the risk of fetal loss was 10 and 6.8 times more likely in cows with low (<2.5 ng/ml) and high (>4 ng/ml) PAG-1 values, respectively, than in cows with medium PAG-1 values, used as reference. Of the 10 inseminating bulls included in the study, one was related to increased fetal loss by odds ratio of 21.7, whereas one bull was attributed fetal loss rate reduced by odds ratio of 12.5 (1/0.08) These findings can have a clear clinical application: PAG-1 measurements from one single sample taken on day 35 of gestation provided more useful information than a series of values obtained from day 35 to 63 of gestation, and can be indicators of subsequent fetal loss.     

Determination of heart rate and heart rate variability in the equine fetus by fetomaternal electrocardiography

Heart rate is an important parameter of fetal well-being. We have analyzed fetal heart rate (HR) and heart rate variability (HRV) by fetomaternal electrocardiography (ECG) in the horse (Equus caballus) from midpregnancy to foaling. It was the aim of the study to detect changes in the regulation of fetal cardiac activity over time and to establish normal values in undisturbed pregnancies. A total of 22 mares were available for the study. Fetomaternal electrocardiography was a reliable technique to detect cardiac signals in fetuses between Day 173 of gestation and foaling. Fetal HR decreased from 115 ± 4 beats/min (Days 170 to 240 of gestation) to 83 ± 3 beats/min (Day 320) to 79 ± 1 beats/min (1 d before foaling; P < 0.001). Mean beat to beat (RR) interval and standard deviation of the RR interval (SDRR) increased (P < 0.001). Gestational age thus affects RR interval and HR in the equine fetus. From Days 270 to 340 of gestation, SDRR increased from 11.4 ± 1.3 msec on Day 270 to 27.8 ± 3.6 msec on Day 340 (P < 0.05), and the root mean square of successive RR differences (RMSSD) tended to increase (P = 0.07), indicating maturation of the fetal autonomous nervous system. For the last 10 d before foaling, fetal HR and HRV remained constant and did not allow predicting the onset of parturition in the horse. Only during the last 30 min before the foal was born, in 4 of 5 fetuses, HR decreased and RR interval increased. Accelerations and decelerations in HR were detectable at all times, but neither their number nor duration changed over time.     

Effect of prenatal exposure to diagnostic ultrasound on the development of mice.

Pregnant Swiss albino mice were exposed to diagnostic ultrasound (3.5 MHz, approximately 65 mW) for 10 min on Day 3.5 (preimplantation period), 6.5 (early organogenesis period), or 11.5 (late organogenesis period) of gestation. Sham-exposed controls were maintained for comparison. Exposed as well as control fetuses were dissected out on the 18th day of gestation, and changes in total mortality, body weight, body length, head length, brain weight, sex ratio, and microphthalmia were recorded. Exposure on Day 3.5 of gestation resulted in a small increase in the resorption rate and a significant reduction in fetal body weight. A low fetal weight and an increase in the number of growth-retarded fetuses were produced by exposure on Day 6.5 postcoitus. A statistically nonsignificant increase in the incidence of microphthalmia was induced in fetuses exposed on Day 6.5 or Day 11.5 of gestation. These results indicate that ultrasound may have some adverse effects on the mouse embryos depending on the developmental stage at which the exposure occurred.     

Current Perspectives on Umbilical Cord Abnormalities Including Blood Flow Parameters Based on Ultrasound Observations

The umbilical cord is a vital structure between the fetus and placenta for the growth and well-being of the fetus. Although the umbilical cord may be the only organ that dies at the beginning of life, it is one of the most important parts of the feta-placental unit and plays a role in determining how life begins. In general, the prenatal examination of the umbilical cord is limited to the observation of the number of vessels and the evaluation of umbilical artery blood flow parameters. Pathologists have done more research on the morphological characteristics of the umbilical cord and linked them to perinatal outcomes. The introduction of advanced imaging technology makes it possible to study the characteristics of fetal umbilical cord from early to late gestation. Many studies have shown that the changes of umbilical cord structure may be related to pathological conditions, such as preeclampsia, fetal growth restriction. Prenatal morphometric umbilical cord characteristics and arterial blood flow parameters in normal and pathologic conditions are discussed in this review.     

Ultrasonographic evaluation of the equine placenta by transrectal and transabdominal approach in the normal pregnant mare

The objective of this study was to determine normal variations in the utero placental thickness during mid- and late gestation in the mare. Normal, healthy pregnant mares (n = 9) were examined monthly from 4 mo of gestation until parturition by transrectal and transabdominal ultrasonography. At each examination, the combined thickness of the uterus and the placenta (CTUP) was measured at the placento-cervical junction (transrectally) and at the uterine body or the uterine horns (transabdominally). In addition, the echogenicity of the amniotic and allantoic fluids was evaluated by transrectal ultrasonography. Following parturition and expulsion of the fetal membranes, the allantochorion was measured and visually examined for abnormalities. At all examinations, both transrectal and transabdominal, the chorioallantois and the uterus were indistinguishable from each other on the ultrasound image. The CTUP, measured by transrectal ultrasonography did not change between 4 and 8 mo of gestation, but increased significantly for each month between 10 and 12 mo of gestation (P < 0.001). A change in the CTUP was detected between months when measured by transabdominal ultrasonography, but no distinct pattern in these changes was observed. No correlation was found between transabdominal and transrectal measurements of the CTUP. The echogenicity of the amniotic and allantoic fluids did not consistently change over time during mid- and late gestation. The amniotic fluid was more echogenic than the allantoic fluid at most examinations from 6 mo of pregnancy and throughout gestation (P < 0.05). It was concluded that transrectal ultrasonographic examination to assess the CTUP and the echogenicity of the fetal fluids is superior to the transabdominal approach. We suggest that transrectal ultrasonographic examination should be added to current diagnostic tools during late gestation and that it be part of the biophysical profile of high risk equine pregnancies.     

Effects of sodium valproate and oxygen on the CD-1 mouse fetus

This study reports the effects of valproic acid (VA) on the CD-1 mouse fetus when the drug is administered continuously via osmotic minipumps at human therapeutic drug plasma levels. Two VA-filled Alzet osmotic minipumps were implanted subcutaneously on gestation day 5 for continuous exposure of a total daily dosage of 850 mg/kg on gestation days 5-12. Dams were then exposed continuously to either normoxic (21% oxygen), hyperoxic (50% oxygen), or hypoxic (12% oxygen) controlled environments during gestation days 5-12, in order to determine if hyperoxic maternal conditions offered a protective environment for the fetus, and conversely, if hypoxia exacerbated teratogenicity. Dams were sacrificed on gestation day 18, and litter and fetal data were collected. It was determined in separate groups under normoxic conditions that the osmotic minipump system maintained VA plasma levels corresponding to human therapeutic levels. Sodium valproate was found to induce developmental toxicity in the CD-1 mouse fetus at human therapeutic drug plasma levels. Fetal weights were reduced, and the number of resorptions, deaths, and hematomas was increased. While hypoxia exacerbated the toxic effect on the fetus, hyperoxia failed to ameliorate the outcome.     

Real-time ultrasonography for determining pregnancy status and viable fetal numbers in ewes

The reproductive tracts of 26 estrus synchronized, bred ewes were scanned with a portable 5.0 MHz real-time ultrasound unit within 1 to 6 d postbreeding. Intrarectal scanning was performed on alternate days until Days 28 to 30 and twice weekly until Days 50 of gestation. Transabdominal uterine scans were conducted twice weekly from Days 25 to 65 and continued weekly until parturition. A total of 24 ewes (92%) became pregnant. A nonpregnant ewe was recognized 100% of the time by both methods of ultrasonic screening. Correct identification of a gravid ewe as pregnant was 100% from Days 51 to 150 of gestation using transabdominal real-time ultrasonography. There was a significant association (P < 0.005) between the number of lambs born and the number of fetuses observed using transabdominal real-time ultrasonography after Day 25 of gestation. Accurate differentiation of fetal numbers by transabdominal scanning was 100.0% for ewes carrying one lamb and 97.3% for ewes carrying two lambs at Days 51 to 75 of gestation. Fetal attrition was documented in one ewe at Day 49 of gestation. Hydrops allantois was diagnosed in another ewe at 110 d of gestation. A total of 37 lambs were born to 23 ewes in the project flock. No congenital abnormalities were noted in any of the lambs. Transabdominal real-time ultrasonography is a safe, rapid, accurate and practical method for assessing pregnancy status, fetal number and fetal viability in sheep.     

Maternal age and parity influence ultrasonographic measurements of fetal growth in Dutch Warmblood mares

Ultrasonographic examination of the equine fetus in mid-late gestation is usually performed only if there are concerns about fetal or maternal health. Even then it is difficult to determine whether development is ‘normal’ for gestational age because the reference values include considerable error margins. This study examined maternal factors that influence fetal growth with the aim of producing more precise late gestation fetal growth curves for Dutch Warmblood horses. Fetal development was monitored at 2-week intervals from day 100 of gestation until term in 32 mares ranging from 4 to 18 years in age; seven of the mares were primiparous. Transrectal and/or transabdominal ultrasonographic measurement of the fetal eye orbit, cranium, aorta, heart rate and of the combined thickness of uterus and placenta (CTUP) were performed using a portable ultrasound machine equipped with 6 MHz linear and 3.5 MHz curved array probes.During days 100–250 of gestation, the CTUP was thicker in primiparous than multiparous mares (p < 0.05). After day 220 the maximum cross-sectional area, but not diameter, of both the eye orbit and cranium were also greater in primiparous than multiparous mares (p < 0.05). Fetal aorta diameter was not influenced by parity but was affected by maternal age, being smaller in mares ≥15 years of age than younger animals (p < 0.05). Only biparietal cross-sectional surface area and aorta diameter increased linearly throughout late gestation. However, even allowing for the effects of parity and maternal age, the late gestational variation in fetal size is such that serial measurements may be required to definitively identify abnormal development.     

Patterns of soluble cellular proteins during fetal rat hepatocyte development

Soluble cellular proteins from fetal rat hepatocytes, at 13-20 days of gestation were analyzed by 2-D gel electrophoresis and compared with protein patterns from adult hepatocytes and two hepatoma lines. The patterns of 13, 15 and 17 day fetal hepatocyte proteins were very similar. A number of proteins which were prominent in early fetal hepatocytes, were absent from the adult hepatocyte. Several proteins, which were also present in the adult pattern, appeared by day 17 of gestation. By day 20 of gestation, numerous proteins appeared and increased levels of a number of other proteins were observed. The adult hepatocyte protein pattern differed markedly from those of fetal hepatocytes. Many proteins present at low levels in fetal hepatocytes were increased in the adult, and at least thirty six new proteins appeared. The protein patterns of two hepatoma lines more closely resembled the early fetal rather than the adult hepatocyte pattern.     

Congenital high airway obstruction syndrome

Congenital high airway obstruction syndrome (CHAOS) is a very rare fetal malformation caused by obstruction of fetal airway because of laryngeal or tracheal atresia, subglottic stenosis, laryngeal cyst or laryngeal web. The prenatal diagnosis is inferred from secondary changes such as enlarged, hyperechogenic lungs, ascites and/or hydrops, flattened or everted diaphragms, dilated distal airways and mediastinal compression. There are only few cases of long-term survival described in literature. We present the case of fetus with such secondary changes diagnosed during routine ultrasound evaluation in 20 weeks' gestation. There were no other abnormalities and the kariotype was normal. In 26 weeks' gestation fetal hydrops appeared and subsequent polyhydramnios occurred in 28 weeks' gestation. The patient was planned for EXIT procedure during labor in experienced in CHAOS cases center. In 29 weeks' gestation the premature rupture of membranes and regular uterine contractions occurred and we've performed cesarean section. A multidisciplinary team of neonatologists, laryngologists and pediatric surgeons made their efforts to save the newborn, but there was complete laryngeal atresia and tracheal agenesia and immediate tracheostomy was impossible. The most important about CHAOS are early diagnosis, detailed fetal assessment and an adequate postnatal intervention for establishing fetal airways.