Individual growth patterns in the first trimester: evidence for difference in embryonic and fetal growth rates.
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OBJECTIVE: To evaluate individual fetal growth during the first trimester in pregnancies resulting from spontaneous and in vitro fertilization (IVF). METHODS: The growth of 11 fetuses conceived by spontaneous fertilization (known dates of ovulation) in nine patients and 15 fetuses conceived by IVF in 12 patients were evaluated at weekly intervals from 6 weeks, menstrual age, to 14 weeks. Fetal length was determined at each examination. Measures of fetal length included the crown-rump length (CRL), maximum straight line length (MSLL) and maximum axial length (MAL). Comparisons of CRL and MSLL to MAL were carried out. The MSLL was used as the measure of length except when the MAL was available. Linear and quadratic functions were fitted to the complete data sets of individual fetuses in the two groups. Individual data sets from ten fetuses in each group were then divided into early and late growth phases, and linear functions were fitted to each data subset. Start points and pivotal points for each fetus were estimated from the coefficients of these two functions. Growth in these two groups of fetuses was compared, on the basis of slope values. RESULTS: Evaluation of length measures indicated that, before 8 weeks, only MSLL could be measured. After 8 weeks, all three measures could be obtained, with the MAL being the largest. Both the linear and quadratic models performed well with individual data sets (mean R2(+/- SD): linear 98.1 (1.0)%; quadratic 99.4 (0.4)%), with no differences found between spontaneous and IVF groups (maximum possible differences in mean slopes (95% probability): 5-8%). Similar findings were obtained for the early and late growth phase data subsets. Slope values in the early and late growth phases showed low variability (CV: early 13.5%; late 11.6%), but were significantly different (early 0.72 (+/- 0.10 SD) cm/week; late 1.21 (+/- 0.14 SD) cm/week). The mean start point was 5.9 (+/- 0.3 SD) weeks' menstrual age, while the mean pivotal point was 9.2 (+/- 0.7 SD) weeks, menstrual age. CONCLUSIONS: First-trimester growth studies in individual fetuses indicate that there is a change in length growth rate between 9 and 10 weeks, menstrual age. This is consistent with a shift in development from organogenesis to growth. These results can be used for more accurate assessment of first-trimester growth and may aid in the detection of fetal problems that manifest themselves as growth abnormalities. (+info)
The 'Mickey Mouse' sign and the diagnosis of anencephaly in early pregnancy.
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OBJECTIVES: To assess the sonographic screening for anencephaly in the first trimester in a low-risk obstetric population. METHODS: Since 1994, 5388 women attended our clinic for a first-trimester scan (11-14 weeks of gestation) and screening for structural and chromosomal abnormalities. The patients underwent transabdominal scanning, and transvaginal scanning if necessary. RESULTS: The ultrasonographic appearances of anencephaly in the first trimester are different from the familiar second-trimester signs. The cerebral hemispheres are present and exposed to the surrounding amniotic fluid. The ultrasound appearances in the coronal section of the head are best described as 'Mickey Mouse face'. There were six cases of anencephaly (incidence 1.1:1000). All cases were diagnosed in the first trimester and five demonstrated this sign. There were no false-positive diagnoses. The crown-rump length was significantly reduced in all affected fetuses. CONCLUSION: First-trimester ultrasonographic diagnosis of anencephaly is accurate, but sonographers should be familiar with the ultrasound appearances that are different from those in the second trimester. (+info)
Biometrical threshold of biparietal diameter for certain fetal sex assignment by ultrasound.
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OBJECTIVES: The aim of this study was to establish the biometric threshold of biparietal diameter (BPD), assumed to be an independent variable of gestational age, at which 100% accuracy in the assessment of fetal sex by ultrasonography is achievable. METHODS: Transvaginal and/or transabdominal sonography was used for detecting the 'sagittal sign' as a marker of fetal sex in 385 fetuses with BPD between 18 and 29 mm. The results of ultrasound examination were compared with sex at birth or with karyotype obtained from amniotic fluid cells or chorionic villus sampling. RESULTS: Fetal sex assignment was feasible in 337 of 385 cases (87.5%). Of the 312 fetuses with known fetal sex outcome, 164 were males and 148 were females. An accuracy rate of 100% was achieved when a BPD of > or = 23 mm was obtained. CONCLUSION: This study provides important information about the earliest stage of fetal development, expressed in terms of BPD, at which a diagnosis of fetal sex can be made with 100% accuracy. (+info)
Maternal cigarette smoking during pregnancy and infant ponderal index at birth in the Swedish Medical Birth Register, 1991-1992.
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OBJECTIVES: This study examined the effect of maternal smoking during pregnancy on infant body proportion. METHODS: The ponderal index, defined as birthweight divided by crown-heel length cubed, was examined in 207,607 infants from the Swedish Medical Birth Register for 1991 and 1992. RESULTS: Infant ponderal index was used as the outcome variable in an ordinary least squares continuous regression, which included early pregnancy smoking status, gestational age, and birthweight among the predictors. Ponderal index increased by 0.030 (+/- 0.0014) among infants of moderate smokers and by 0.040 (+/- 0.0017) among infants of heavy smokers, showing a dose response. CONCLUSIONS: Smoking differentially alters the trajectory of weight vs length growth in the fetus. (+info)
Relationship between fetal femur diaphysis length and neonatal crown-heel length: the effect of race.
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OBJECTIVE: To determine whether racial differences affect the relationship between the fetal femur diaphysis length and the neonatal crown-heel length. DESIGN: A prospective study in a teaching hospital with a multiracial population. SUBJECTS: Four hundred and fifty pregnant women (150 Malays, 150 Chinese and 150 Indians) who delivered live infants. METHODS: Ultrasound scan measurement of the fetal femur diaphysis length was carried out within 48 h of delivery in all cases. The relationship between the neonatal crown-heel length and the femur diaphysis length was obtained by regression using the method of least squares. Dummy or indicator variables were used to determine the effect of race on the relationship. RESULTS: The relationship between the neonatal crown-heel length and the femur diaphysis length in all three races was well described by a linear model but a quadratic model described the relationship better. There was no significant difference in relationship of the neonatal crown-heel length and the femur diaphysis length between the Malay and Chinese populations, but the relationship in the Indian population was significantly different was from both the Chinese and Malay. For a given femur diaphysis length, the crown-heel length of the Indian population was found on average to be 1.1 cm shorter than the crown-heel length of the Malay and Chinese populations. CONCLUSION: Differences in fetal body proportions exist between some races. The longer femur diaphysis length noted in certain races does not necessarily imply that the corresponding crown-heel length is longer. These inter-racial differences may increase the error of fetal weight and length estimates if formulae, which have been derived from samples racially dissimilar to that of the target population are used. (+info)
Gestational age in pregnancies conceived after in vitro fertilization: a comparison between age assessed from oocyte retrieval, crown-rump length and biparietal diameter.
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OBJECTIVE: To compare gestational age (GA) and day of delivery estimated from the time of in vitro fertilization (IVF) (oocyte retrieval + 14 days), the ultrasonic measurement of the crown-rump length (CRL) and the biparietal diameter (BPD) in pregnancies conceived in an IVF setting. DESIGN: Included were 208 singletons and 72 twin pregnancies conceived after IVF. GA estimated from the time of IVF was compared with the GA estimated from the ultrasonic measurement of the CRL in the first trimester and the BPD in the second trimester. RESULTS: In singletons the mean difference in gestational age was 0.9 days between IVF and CRL estimates and 2.1 days between IVF and BPD estimates. The gestational age as estimated from CRL or BPD was shorter than the GA estimated from IVF. There was no systematic variation in the mean differences in GA between the methods. In three pregnancies there was a difference of more than 7 days between the gestational age estimated from IVF and CRL and in 22 pregnancies between gestational age estimated from IVF and BPD. A difference of > 14 days for any of the estimates was not found in any case. In singletons there was a high correlation in the gestational age at birth assessed from the time of IVF and from CRL, from the time of IVF and from BPD. CONCLUSION: Assessment of gestational age from the time of IVF, CRL and BPD in pregnancies conceived after IVF shows equally high agreement between the three methods. This supports the use of ultrasound as a reliable method for estimation of gestational age. (+info)
Alobar holoprosencephaly at 9 weeks gestational age visualized by two- and three-dimensional ultrasound.
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We present the ultrasound detection of alobar holoprosencephaly (HPE) with cyclopia in an embryo of 9 weeks 2 days last menstrual period (LMP)-based gestational age; the crown-rump length (CRL) was 22 mm. The use of three-dimensional (3-D) ultrasound made additional diagnostic ultrasound tomograms possible, and the volume reconstructions improved the imaging and the understanding of the condition. (+info)
The prenatal cranial base complex and hand in Turner syndrome.
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From early childhood, Turner syndrome patients have a flattened cranial base, maxillary retrognathism, and short hands. There are, however, no studies that show when these genotype-determined abnormalities occur prenatally. The purpose of the present study was to measure craniofacial profile and hand radiographs of second trimester foetuses with Turner syndrome and compare the results with similar measurements from normal foetuses. The subjects consisted of 12 Turner syndrome foetuses, gestational age (GA) varying between 15 and 24 weeks, and crown-rump length (CRL) between 108 and 220 mm. The mid-sagittal block of each cranium was analysed as part of the requested brain analysis (pituitary gland analysis). This block and the right hand from seven foetuses were radiographed, and the skeletal maturity of the cranial base complex, i.e. the cranial base and the maxilla, was evaluated from the profile radiographs. Shape and size measurements in the cranial base were performed, and compared with normal values according to cranial maturity and to CRL. The cranial base angle in Turner syndrome was greater and the maxillary prognathism was reduced compared with the normal group. The dimensions in the cranial complex and in the hand showed that the bone lengths and distances in relation to CRL were generally smaller compared with normal foetuses. This investigation showed that the abnormal shape of the cranial base complex and the short hands in Turner syndrome are present prenatally. (+info)