Estimation Of Gestational Age Research Articles

Three-dimensional ultrasonography using the VOCAL technique for estimation of reference range between 7 and 11weeks embryonic volume

Abstract Objective Accurate estimation of gestational age (GA) is the basis of vital decisions in pregnancy and hence its importance in obstetric management. This study tries estimating a reference range of 3D embryonic volume using the VOCAL technique for pregnancies between 7 and 11 weeks. Materials and methods This cross-sectional study included 62 singleton normal uneventful pregnancies. All women were essentially sure of the date of last menstrual period. All women were submitted to 3D ultrasonographic examination with VOCAL technique to determine the embryonic volume. In addition the crown-rump length was measured. Regression analysis was performed to predict the gestational age from the fetal volume. Results There was a strong positive correlation between embryonic volume and menstrual age, gestational age and crown-rump length (r = 0.919, 0.938 and 0.941, respectively). Power regression model produced R2 value of 0.838 with a regression equation (y = 52.22 + 6.5 x). Conclusion This study demonstrated that embryonic/fetal volume is a good predictor of gestational age with a power regression equation (y = 52.22 + 6.5 x) for the period from 7 to 10 weeks + 6 days. We suggest using the embryo volume as an early evidence of growth restriction in high risk pregnancy.

Matched sample comparison of intramuscular versus vaginal micronized progesterone for prevention of preterm birth

Objectives: To compare vaginal with intramuscular progesterone administration to prevent preterm labor in women with singleton pregnancies and at increased risk of preterm birth.Study design: Prospective comparative clinical trial.Population: One hundred and sixty pregnant women at 20–24 weeks gestation at the risk of preterm labor were classified into: 80 women who received micronized progesterone tablets 200 mg vaginally daily (Group A) and 80 women who received 100 mg progesterone in the form of intramuscular every third day (Group B).Methods: Estimation of gestational age, assessment of fetal growth and fetal biophysical profile by trans-abdominal ultrasonographic examination was done every 4 weeks till delivery. Measurement of cervical length was achieved by transvaginal ultrasonography, done every 4 weeks till delivery.Main outcome measures: Incidence of preterm delivery, mean gestational age and the incidence of adverse events of intramuscular versus vaginal route of progesterone administration.Results: The incidence of preterm delivery in Group A was 20% and in Group B was 27.5%. The difference between both groups was statistically insignificant. In addition, the rate of adverse events reported in women received injectable progesterone was significantly higher than the rate of adverse events reported in women who received vaginal progesterone therapy.Conclusion: Vaginally administrated progesterone was nearly as equally effective as intramuscular progesterone in the prevention of preterm labor in women at risk and in the meantime has less undesirable events.

Intrauterine Growth Restriction: Effects of Physiological Fetal Growth Determinants on Diagnosis

The growth of the fetus, which is strongly associated with the outcome of pregnancy, reflects interplay of several physiological and pathological factors. The assessment of fetal growth is based on comparison of birthweight (BW) or estimated fetal weight (EFW) to standards which define reference ranges at a spectrum of gestational ages. Most birthweight standards do not take into account effects of physiological determinants of fetal growth. Additionally, gestational age in many standards is based on the menstrual history and is often inaccurate. Fetal growth norms should be based on an early ultrasound estimate of gestational age. Customized standards, which have included only ultrasound-dated pregnancies, seem to be superior to population-based birthweight norms in predicting perinatal mortality and morbidity. Adjustment for individual variation in customized growth curves reduces false-positive diagnosis of IUGR and may lead to a very significant reduction in intervention for suspected IUGR. Customized growth potential identifies better the risk for adverse outcome than the currently used national standards, but customized charts may fail in detecting growth-restricted stillbirth. An individual's birthweight is the sum of physiological and pathological influences operating during pregnancy. Growth potential norms are a better discriminator of aberrations of fetal growth than population, ultrasound, and customized norms.

Determination of gestational age in twin pregnancy: Which fetal crown–rump length should be used?

For twin pregnancy, discrepancies in the crown-rump length (CRL) between two fetuses often exist. Evidence is lacking regarding which fetal CRL should be used for estimation of gestational age (GA). Our aim was to determine whether the larger, smaller or the mean CRL is more accurate in determining the GA in the first trimester of pregnancy. This is a retrospective study of twin pregnancies conceived by assisted reproduction. The oocyte retrieval date was used for determination of the true gestational age. CRL dating charts by Robinson, Hadlock and Chitty were used for reference. The values of the larger, smaller and mean CRL were compared with the reference CRL for the corresponding GA, which was obtained from each of the three reference charts. The differences between the reference CRL and measured CRL were calculated. The percentages of which CRL, the larger, smaller or the mean, was closest to the expected reference values were calculated. A total of 52 pairs of twins were included in the study. According to Robinson's chart, the proportion of larger, smaller and mean CRL values that were closest to the reference value was found in 11.5%, 75.0% and 5.8% of cases respectively. The larger, smaller and the mean CRLs were closest to the reference CRL in the Hadlock chart for 28.9%, 44.2% and 19.2% of cases, respectively, and closest to the reference CRL in the Chitty chart for 17.3%, 59.6% and 15.4% of cases, respectively. The smaller CRL is more accurate in the estimation of the GA for twin pregnancy compared to the larger or mean CRL values.

Accuracy of emergency physician performed bedside ultrasound in determining gestational age in first trimester pregnancy

BackgroundPatient reported menstrual history, physician clinical evaluation, and ultrasonography are used to determine gestational age in the pregnant female. Previous studies have shown that pregnancy dating by last menstrual period (LMP) and physical examination findings can be inaccurate. An ultrasound performed in the radiology department is considered the standard for determining an accurate gestational age. The aim of this study is to determine the accuracy of emergency physician performed bedside ultrasound as an estimation of gestational age (EDUGA) as compared to the radiology department standard.MethodsA prospective convenience sample of ED patients presenting in the first trimester of pregnancy (based upon self-reported LMP) regardless of their presenting complaint were enrolled. EDUGA was compared to gestational age estimated by ultrasound performed in the department of radiology (RGA) as the gold standard. Pearson’s product moment correlation coefficient was used to determine the correlation between EDUGA compared to RGA.ResultsSixty-eight pregnant patients presumed to be in the 1st trimester of pregnancy based upon self-reported LMP consented to enrollment. When excluding the cases with no fetal pole, the median discrepancy of EDUGA versus RGA was 2 days (interquartile range (IQR) 1 to 3.25). The correlation coefficient of EDUGA with RGA was 0.978. When including the six cases without a fetal pole in the data analysis, the median discrepancy of EDUGA compared with RGA was 3 days (IQR 1 to 4). The correlation coefficient of EDUGA with RGA was 0.945.ConclusionBased on our comparison of EDUGA to RGA in patients presenting to the ED in the first trimester of pregnancy, we conclude that emergency physicians are capable of accurately performing this measurement. Emergency physicians should consider using ultrasound to estimate gestational age as it may be useful for the future care of that pregnant patient.

Impact of ovulation and implantation timing on first‐trimester crown–rump length and gestational age

To determine the impact of ovulation and implantation timing on first-trimester crown-rump length (CRL) and the derived gestational age (GA). One hundred and forty-three women who were trying to conceive were recruited prospectively. The timing of ovulation and implantation and the ovulation to implantation (O-I) interval were established in 101 pregnancies using home urinary tests for luteinizing hormone and human chorionic gonadotropin. In 71 ongoing pregnancies, GA determined by measurement of fetal CRL at 10-14 weeks' gestation was compared with GA based on ovulation and implantation day. First-trimester growth was determined by serial ultrasound scans at 6-7, 8-9 and 10-14 weeks. The median ovulation and implantation days were 16 and 27, respectively, with an O-I interval of 11 days. GA estimated from CRL at 10-14 weeks was on average 1.3 days greater than that derived from ovulation timing. CRL Z-score was inversely related to O-I interval (ρ= -0.431, P=0.0009). There was no significant relationship between CRL growth rate and the difference between observed CRL and expected CRL based on GA from last menstrual period (ρ=0.224, P=0.08). Early implantation leads to a larger CRL and late implantation to a smaller CRL at 10-14 weeks, independent of CRL growth rate. Implantation timing is a major determinant of fetal size at 10-14 weeks and largely explains the variation in estimates of GA in the first trimester derived from embryonic or fetal CRL.

A population pharmacokinetic model of piperaquine in pregnant and non-pregnant women with uncomplicated Plasmodium falciparum malaria in Sudan

BackgroundPregnancy is associated with an increased risk of developing a malaria infection and a higher risk of developing severe malaria. The pharmacokinetic properties of many anti-malarials are also altered during pregnancy, often resulting in a decreased drug exposure. Piperaquine is a promising anti-malarial partner drug used in a fixed-dose combination with dihydroartemisinin. The aim of this study was to investigate the population pharmacokinetics of piperaquine in pregnant and non-pregnant Sudanese women with uncomplicated Plasmodium falciparum malaria.MethodSymptomatic patients received a standard dose regimen of the fixed dose oral piperaquine-dihydroartemisinin combination treatment. Densely sampled plasma aliquots were collected and analysed using a previously described LC-MS/MS method. Data from 12 pregnant and 12 non-pregnant women were analysed using nonlinear mixed-effects modelling. A Monte Carlo Mapped Power (MCMP) analysis was conducted based on a previously published study to evaluate the power of detecting covariates in this relatively small study.ResultsA three-compartment disposition model with a transit-absorption model described the observed data well. Body weight was added as an allometric function on all clearance and volume parameters. A statistically significant decrease in estimated terminal piperaquine half-life in pregnant compared with non-pregnant women was found, but there were no differences in post-hoc estimates of total piperaquine exposure. The MCMP analysis indicated a minimum of 13 pregnant and 13 non-pregnant women were required to identify pregnancy as a covariate on relevant pharmacokinetic parameters (80% power and p=0.05). Pregnancy was, therefore, evaluated as a categorical and continuous covariate (i.e. estimate gestational age) in a full covariate approach. Using this approach pregnancy was not associated with any major change in piperaquine elimination clearance. However, a trend of increasing elimination clearance with increasing gestational age could be seen.ConclusionsThe population pharmacokinetic properties of piperaquine were well described by a three-compartment disposition model in pregnant and non-pregnant women with uncomplicated malaria. The modelling approach showed no major difference in piperaquine exposure between the two groups and data presented here do not warrant a dose adjustment in pregnancy in this vulnerable population.

Determining the Gestational Age of Crioulo Mares Based on a Fetal Ocular Measure

The practice of covering in herds is often used in Crioulo breeding farms, thus not allowing the determination of ovulation dates and the early detection of pregnancies. This fact complicates the estimation of gestational age after 70 days of conception. This study aimed to evaluate the diameter of the fetal orbits of Crioulo mares to develop a formula to estimate a gestational date. Measurements of 164 fetal ocular orbits were performed in 124 Crioulo mares with gestational ages ranging between 119 and 341 days. The current study observed a linear growth pattern of Crioulo fetal orbits up to 341 days of gestation. Thus, obtaining a suitable linear regression model to determine the gestational age of Crioulo mares based on fetal ocular orbit diameter measure is possible. The obtained model was y = 8.3756x + 11.90, where y represents the gestational age in days, and x represents the diameter of the fetal ocular orbit in millimeters. This formula had an r2 of 0.985 (P < .001). We conclude that this model allows researchers and veterinarians to accurately estimate the gestational age of Crioulo mares between 4 and 11 months of pregnancy.

Effect of various dating formulae on sonographic estimation of gestational age in extremely preterm infants

Gestational age (GA) is one of the most important obstetric factors and prediction of date of delivery is usually based on ultrasonographic fetal measurements. Our aim was to determine whether applying three different dating formulae to a cohort of extremely preterm infants influenced the estimation of their GA. This was a study of 513 infants delivered before 27 gestational weeks, included in a Swedish national population study (EXPRESS), with information available on mid-trimester ultrasonographically measured biparietal diameter and femur length. We applied using these parameters three dating formulae, the Persson & Weldner formula, commonly used in Sweden, the Hadlock formula and the Mul formula, and compared their GA estimates to the clinically reported GA (recorded at delivery) and the last menstrual period (LMP)-based GA. The mean reported GA was 173.2 days, corresponding well to the GA according to the Persson & Weldner dating formula (173.3). The mean GA according to LMP, the Hadlock formula and the Mul formula were 176.8, 175.3 and 175.6 days, respectively. The Hadlock and Mul GA estimates differed significantly from that based on the Persson & Weldner formula (both P-values < 10(-6)). Among 68 pregnancies with a reported duration of 22 weeks, 33 (49%) had a duration of 23 weeks or more when GA was calculated according to LMP and 22 (32%) when GA was calculated according to the Hadlock formula. Estimated GA among infants delivered before 27 gestational weeks varied significantly depending on the dating formula used to calculate the estimated date of delivery; this might influence the clinical management of extremely preterm fetuses and infants.

Assessment of gestational age using cerebellar measurements at cranial ultrasound: What is the best approach?

Background and aimsClinical assessment of gestational age (GA) in preterm infants can be challenging. Several ultrasound approaches for estimating GA using cerebellar measurements are reported, claiming to be simpler and more accurate than clinical assessment, but they are not widely used. We aimed to compare the accuracy of four previously described measurements and compare their use in preterm infants. MethodsWe studied infants <32weeks of GA defined by in-vitro fertilization date or early fetal ultrasound, excluding infants with neurological problems. Vermis anterior–posterior diameter (VAPD), vermis height (VH), and transverse cerebellar diameter via anterior (TCDa) and mastoid fontanelles (TCDm) were measured.Estimated PMA was calculated using published equations, and compared to known PMA using intraclass correlation coefficient (ICC). Intra and inter-observer reliability were determined. ResultsWe studied 80 infants (mean GA 28.5weeks [range 24–32], mean post-natal age 5.7days). ICC was 0.761 (VAPD), 0.632 (VH), 0.115 (TCDa) and 0.825 (TCDm). The TCDm equation gave the best estimate of GA (mean estimate −2days; 95% CI±13.8days). TCDa and TCDm absolute measurements were similar for each infant. Accuracy for estimating GA was similar for appropriately grown and small-for-gestation infants. Inter and intra-observer reliability was very good for all measurements. ConclusionsThree previously described equations for estimating GA from cerebellar measurements gave good estimates of GA in preterms. The equation described for TCDm gave the narrowest 95% CI. We recommend the TCDm equation for the estimation of GA in VLBW infants but the TCD measurement can be made via either the anterior or mastoid fontanelle.

Association Between Preterm Delivery and Pre-pregnancy Body Mass (BMI), Exercise and Sleep During Pregnancy Among Working Women in Southern California

Little is known about modifiable lifestyle factors beyond quitting smoking that could prevent preterm delivery (PTD, <37 weeks gestation). We examined the individual and joint associations of pre-pregnancy BMI, second trimester exercise and sleep on PTD. We conducted a nested, population-based case-control study interviewing postpartum 344 cases delivering at <37 weeks, as identified by clinical estimate of gestational age from prenatal screening records, and 698 term controls, excluding term low birthweight. Eligible women participated in California's statewide Prenatal Screening Program, worked during pregnancy, and delivered a singleton birth in Southern California in 2002-2003. Modeled separately, moderate (odds ratio [OR] = 0.90; 95% confidence interval [CI] = 0.84-0.96--per hour/week) and vigorous (OR = 0.67; 95% CI = 0.46-0.98 for yes vs. no) exercise during the second trimester were associated with a reduced odds of PTD, and sleep duration was not (OR = 1.09, 95% CI = 0.80-1.48 for <7 h; OR = 0.88, 95% CI = 0.57-1.48 for >8 h vs. 7-8 h). When sleep and exercise variables were modeled together along with pre-pregnancy BMI, only moderate exercise (OR = 0.91; 95% CI 0.85-0.98) continued to be associated with reduced odds of PTD. The benefits of moderate exercise appeared strongest for women with BMI greater than 24 kg/m(2) (OR = 0.85; 95% CI = 0.79-0.93) and weakened with decreasing BMI. No other interactions were found. Moderate exercise is associated with reduced PTD, particularly for women with BMI above the normal range. The results are of public health relevance given that these risk factors are potentially modifiable both pre-conceptionally and during pregnancy and rates of PTD are still high in the United States.

Gestational age estimation using transcerebellar diameter with grading of fetal cerebellar growth

Abstract Background : The transverse cerebellar diameter (TCD) serves as a reliable predictor of gestational age (GA) of the fetus and is a standard against which aberrations in other fetal parameters can be compared, especially when the GA cannot be determined by the date of the last menstrual period or an early pregnancy scan. Aim : The aim of this study was to derive a regression equation and evaluate the relationship between transverse cerebellar diameter and gestational age, which will be helpful in assessing the fetal gestational age and also to evaluate the grades of cerebellum and to see its growth. Materials &amp; methods : The prospective study was carried out in 292 pregnant women between 14-40 weeks of pregnancy attending the Konaseema Institute of Medical Sciences &amp; Research Foundation, Amalapuram for routine ultrasound examination. Transverse cerebellar diameter was measured and cerebellum was graded using ultrasonography. Results : Fetal cerebella were found to be in 29%, 10% and 61 % cases as grade I, II and III respectively. The grade changed from I to III progressively with advancing gestation. The median GA and TCD were 20 wks and 22 mm for grade I, 32 wks and 30 mm for grade II and 36 wks and 38 mm for grade III. Conclusion : Regression analysis indicated a strong relationship between TCD and gestational age indicating TCD is a good marker for estimation of gestational age.

The estimation of gestational age of pregnancy for use in screening for Down syndrome using ultrasound measurements and embryo transfer date

The estimation of gestational age of pregnancy for use in screening for Down syndrome using ultrasound measurements and embryo transfer date

Fetal organ weight estimation by postmortem high‐field magnetic resonance imaging before 20 weeks' gestation

To ascertain whether high-field magnetic resonance imaging (MRI) allows accurate estimation of the weight of various fetal organs at postmortem before 20 weeks' gestation. From 23 fetuses at 9-20 weeks, following termination of pregnancy or in-utero fetal death (IUFD), 207 assorted fetal organs were evaluated by high-field MRI at 9.4 T prior to conventional autopsy. Fetal organ density was calculated by correlating volume and weight at autopsy using linear regression analysis, and this was used to estimate fetal organ weight by MRI. The relative error in MRI estimation of organ weight was calculated as follows: (|MRI weight - autopsy weight|/autopsy weight) × 100 (%). Multiple regression analysis was used to investigate the effect on the relative error of MRI organ weight estimates of gestational age at TOP or delivery following IUFD, autopsy weight, fetal organ examined, IUFD and fetal maceration. Of the 207 organs evaluated, 133 (64%) were examined for fetal organ density and 155 (75%) for fetal organ weight. Fifty-two organs were excluded from our analysis; 41 of these were from fetuses with IUFD, with 39 organs macerated. In 32 cases, exclusion was due to an inability to assess the organ both on MRI and on conventional autopsy. Volume and weight at autopsy correlated significantly, following the linear equation: autopsy volume = (0.9947 × autopsy weight) - 4.7556, where autopsy volume is in mm(3) and weight is in mg (r = 0.99, P < 0.001). Overall the mean relative error in the MRI estimation of organ weight was 68%. Multiple regression analysis showed that the relative error in the MRI estimation of organ weight was significantly associated with gestational age at TOP or delivery following IUFD and fetal maceration, but not with autopsy weight, fetal organ examined or IUFD. In the subgroup of non-macerated organs and for fetuses above 14 weeks' gestation, the mean relative error in the MRI estimation of organ weight was 34%. In fetuses before 20 weeks' gestation, noninvasive estimation of organ weight is feasible using high-field MRI, but there is a mean overestimation. Limitations of the technique occur mainly in cases of small macerated fetuses before 14 weeks' gestation.

Early childhood development when second-trimester ultrasound dating disagrees with last menstrual period: a prospective cohort study

BackgroundWhen an ultrasound-based estimate of gestational age (GA) is less (greater) than an estimate based on a definite last menstrual period, the fetus may grow slower (faster) than average. While the association between these discrepancies in GA estimates and adverse perinatal outcomes has been examined extensively, there is scant evidence about long-term effects, such as child neurodevelopment.MethodsUsing data from a prospective cohort study titled, NICHD Study of Successive Small-for-Gestational Age Births, we examined if GA discrepancies in early second trimester of pregnancy (17 weeks’ gestation) are associated with: (1) impaired motor and mental function at 13 months (measured using Bayley Scales of Infant Development (Bayley)), and (2) impaired cognitive development at five years (assessed by Wechsler Preschool and Primary Scale of Intelligence – Revised Intelligence Quotient (WPPSI-R)) in the infant. The study population consisted of 572 (30% of the overall sample of 1,945) women who presented for prenatal care in Norway and Sweden between 1986 and 1988.ResultsOur results showed that GA discrepancies in early second trimester are significantly associated with birthweight. We found no significant relationship, however, with the Bayley development scores at 13 months and with the WPPSI-R IQ measures at five years.ConclusionsGA discrepancies at 17 weeks’ gestation are not associated child neurodevelopment. These discrepancies do, however, relate to birthweights, providing a basis for detecting fetal growth patterns early in the second trimester of pregnancy. Our study, however, was unable to evaluate the impact of first-trimester discrepancies on impaired neurodevelopment in the infant.

Cross sectional study to determine gestational age by metrical measurements of foot length

Gestational age estimation is essential in certain condition while performing foetal or neonatal autopsy. This study was conducted to assess the gestational age by foot length of foeti. Foot lengths of 126 foeti (77 live and 49 dead) were included in this study. The objective of this study was to assess the accurate gestational age by simple, non-invasive and economical method. The foot length was measured using vernier caliper between the posterior aspect of the heel to the tip of the longest toe. It was observed that there was an increase of 4.11 gestational weeks for increase in 1cm of foot length. The results were encouraging and comparable with other similar studies. The foot length (independent variable) is strongly related with the period of gestation. As this method is simple, economical and accurate it can be used by a basic medical doctor and also paramedical even in a rural setup.

Are the cardiac dimensions spared in growth‐restricted fetuses resulting from uteroplacental insufficiency?

The aim of this study was to investigate the effect of intrauterine growth restriction (IUGR), specifically from uteroplacental insufficiency, on fetal cardiac dimensions. Cardiac circumference (CC) and cardiac area (CA) were measured in four-chamber view in 143 normal fetuses between 18 and 40 weeks of gestation. A study group comprised a homogeneous group of 49 IUGR fetuses with abnormal umbilical artery impedance. Multiple regression analysis was used to compare the cardiac dimensions between normal and IUGR fetuses and to determine if there were differences in cardiac measurements between those with normal and with abnormal ductus venosus Doppler. Fetal cardiac dimensions did not differ significantly between normal and IUGR fetuses. In IUGR fetuses, cardiac dimensions were not statistically different between those with normal and abnormal ductus venosus Doppler. Cardiac dimensions are spared and may be used for gestational age estimation in growth-restricted fetuses resulting from uteroplacental insufficiency.

First trimester sonographic dating formula for the Nigerian obstetric population

Objective: The main purpose of this study is to derive a dating formula for the Nigerian obstetric population, quantify its prediction error, and compare its performance with existing published formulae. Materials and Methods: The crown-rump length (CRL) of 322 fetuses without risk for fetal growth restriction were plotted against menstrual age to obtain a scatter plot from which we derived the best-fit fractional polynomial regression model for estimating gestational age (GA). The accuracy of the formula was compared with that of existing formula in another data set of 88 fetuses. Results: The scatter plot yielded a best-fit equation for the estimation of GA (in weeks) from CRL (in mm) as GA=−0.0008 (CRL2) + 0.168 CRL + 5.397, (R2=0.8017). The mean prediction error was 0.13 for our formula, and 0.16 and 0.20 for Nelson's, and Robinson's formulae, respectively. Conclusion: Our dating formula locally derived was more favorably applicable for the Nigerian population. This has implication for prenatal diagnosis in Nigeria.

Gestational age estimation using transcerebellar diameter with grading of fetal cerebellar growth

Background: The transverse cerebellar diameter (TCD) serves as a reliable predictor of gestational age (GA) of the fetus and is a standard against which aberrations in other fetal parameters can be compared, especially when the GA cannot be determined by the date of the last menstrual period or an early pregnancy scan. Aim: The aim of this study was to derive a regression equation and evaluate the relationship between transverse cerebellar diameter and gestational age, which will be helpful in assessing the fetal gestational age and also to evaluate the grades of cerebellum and to see its growth. Materials & methods: The prospective study was carried out in 292 pregnant women between 14-40 weeks of pregnancy attending the Konaseema Institute of Medical Sciences & Research Foundation, Amalapuram for routine ultrasound examination. Transverse cerebellar diameter was measured and cerebellum was graded using ultrasonography. Results: Fetal cerebella were found to be in 29%, 10% and 61% cases as grade I, II and III respectively. The grade changed from I to III progressively with advancing gestation. The median GA and TCD were 20 wks and 22 min for grade I, 32 wks and 30 mm for grade II and 36 wks and 38 mm for grade III. Conclusion: Regression analysis indicated a strong relationship between TCD and gestational age indicating TCD is a good marker for estimation of gestational age.

Placental thickness & its correlation to gestational age & foetal growth parameters- a cross sectional ultrasonographic study.

The Gestational Age (GA) is frequently over or under estimated, as the conventional gestational estimation is based on the Last Menstrual Period (LMP) and on ultrasonography (USG). Many people are unaware of their LMP and irregular menstruations and USG is bound to have a bias, thereby posing difficulties in the GA estimation. This study was aimed at estimating the (Placental Thickness) PT and at investigating the relationship between PT and the foetal growth parameters in normal singleton pregnancies. Two hundred eleven pregnant women were recruited in a cross sectional prospective study. The pregnancies were between 11 to 40 weeks and they were not complicated by either maternal or foetal diseases. The Biparietal Diameter (BPD), the Abdominal Circumference (AC), the Head Circumference (HC), the Femur Length (FL) and the PT were measured by USG by using a 3.5 MHz transducer. The maximum mean PT in the 1st, 2nd, 3rd and the combined trimesters were 16.5 mm, 23.78 mm, 35.81 mm and 28.49 mm respectively. The correlation between PT and the other foetal parameters was investigated by Pearson's correlation analysis. The values were expressed as mean + standard deviation. The statistical tests were two-tailed, with a p value of < 0.01, which indicated the statistical significance. There was a strong positive correlation between PT and GA, with the correlation coefficient values for the 1st, 2nd and 3rd trimesters being r = 0.609, r = 0.812 and r = 0.814 respectively. There was a significant positive correlation between PT and BPD, AC, FL, ABC, HC and FW also. The mathematical relationships between PT and GA, BPD, AC, FL, ABC, HC, FW were derived by regression analysis. The regression equation which was derived was (x - 22.92) = (0.3604) (w-27.86446) + (1.0256)(y-1.1678) + (0.0015)(z-216.2841) + (0.1047) (t-43.1555) + (0.027) (u.192.79000) + (0.0042) (v-60.3725), where x = GA in weeks, w = PT in mm, y = FW in kg, z = HC in mm, t = FL in mm, u = AC in mm and v = BPD in mm. We conclude that PT can be used as a predictor of the GA. The subnormal PT for the corresponding GA should be evaluated for any disease condition. So, the measurement of PT should therefore be carried out routinely during the obstetric USGs.