European Journal of Cardiovascular Medicine

Precise determination of fetal weight is crucial in the supervision of labor and childbirth. In recent years, the practice of include estimated fetal weight in the regular antepartum assessment of high-risk pregnancies and deliveries has become common. Examples include the administration of diabetes pregnancy, vaginal birth following a prior cesarean section, and intrapartum treatment.

The care of fetuses in the breech position will be significantly impacted by the projected weight of the fetus.[1,2]
Furthermore, in cases of expected premature birth, perinatal counseling may rely on the estimation of anticipated birth weight to determine the likelihood of survival, the interventions used to delay premature delivery, the most suitable method of delivery, and the appropriate level of hospital for the delivery. Classifying fetal weight as either little or large for gestational age can result in obstetric interventions being performed at specific times, which significantly deviate from standard prenatal care.[3-5] A significant proportion of this issue is associated with birth weight, which continues to be the 

primary factor determining the survival of newborns.[6,7]  Approximately 16% of newborns are believed to have low birth-weight, a condition that is linked to increased rates of illness and death throughout the perinatal period. Fetal macrosomia is linked to maternal morbidity, shoulder dystocia, delivery hypoxia, and birth trauma.[8]  In 1991, the Obafemi Awolowo University Teaching Hospital Complex in IleIfe reported an incidence of 1.6% of macrosomia. In the series from 1983 to 1985 at the Lagos University Teaching Hospital, a higher prevalence of 4.9% was reported.[9]
Precise estimation of fetal weight is believed to be beneficial for effectively managing labor, providing care for newborns during the neonatal period, and preventing complications related to fetal macrosomia in low-birth-weight infants. This, in turn, reduces perinatal morbidity and mortality rates.[10] The primary approaches utilized in contemporary obstetrics for determining birth-weight are clinical techniques involving abdominal palpation of fetal components and calculations based on fundal height. Sonographic measurements of fetal skeletal structures are utilized in regression models to calculate predicted fetal weight. While several researchers argue that sonographic estimations are superior to clinical estimates, others who have compared both procedures simultaneously have found that they provide equivalent levels of accuracy.[10]

The available techniques can be categorized into broad classifications:

Medical techniques Assessment of fetal size through touch, such as using Leopold's maneuver; evaluation of clinical risk factors; estimation of fetal weight by the mother; and prediction of birth weight using mathematical calculations. Imaging techniques Ultrasonography and magnetic resonance imaging are two diagnostic techniques. The objective of this investigation is to assess the precision of clinical and ultrasonographic methods in estimating fetal weight, and to determine their link with the actual birth weight. The aims of this study are to assess the agreement between clinically estimated fetal weight and actual birth weight, to evaluate the agreement between ultrasonographic estimated fetal weight and actual birth weight, to establish the correlation between clinically estimated fetal weight and actual birth weight, to determine the correlation between ultrasonographic estimated fetal weight and actual birth weight, and to examine the correlation between clinically estimated fetal weight and ultrasonographic weight, followed by the correlation with actual birth weight.

The study was a prospective study. The sample size consists of 70 term pregnant women fir as per our inclusion criteria. All term pregnant women with a singleton pregnancy , cephalic presentation , coming in early stages of labor and who are 18 years of age or older and visiting the Antenatal Care Outpatient Department (ANC OPD)were included while Pregnant women with fetal congenital anomalies, multiple pregnancies, coming in late phases of labor, Malpresentation, with a pelvic mass, Intra-uterine death and or with Polyhydramnios / oligohydramnios were excluded.

Objective of present study were as follows

1. Determination of fetal weight using clinical methodology and ultrasound.
2. The correlation between the estimated birth weight and the actual birth weight.
   3. The objective is to ascertain the comparative accuracy of clinical and sonographic methods for estimating fetal weight.
   • Methodology

Assessment of fetal weight using Dare's formulas in a clinical setting. Following the completion of bladder voiding and the correction of dextrorotation of the uterus, a clinical weight estimation was conducted. The mother was instructed to recline in a supine position with her legs straightened, and her symphysio-fundal height (SFH) was measured using a tape measure both before birth and at the level of the umbilicus. Additionally, the abdominal girth was measured. Participants and case files are queried regarding their age, date of their most recent menstrual period, duration of pregnancy, and number of previous pregnancies.

• Dare’s formulae

Weight in grams = Abdominal Girth (centimeters) x Symphysiofundal Height(centimeters).

• Hadlock’s formula

After the Head Circumference (HC), Abdominal Circumference (AC), and Femur Length (FL) of the fetus was measured in centimeters, the sonography machine calculates the fetal weight.

Log (10) BW=1.335-0.0034 (abdominal circumference) (femur           length)            +0.0316(bi-parietal            diameter)

+0.0457(AC)+0.1623(FL).

Both clinical and ultrasound estimates were documented in a chart. The infant's birth weight was determined within half an hour after delivery using a traditional analog scale.
The accuracy of clinical or sonographic fetal weights compared to the actual birth weight was evaluated using percentage error, absolute error, and the proportion of estimations within 10% of the actual birth weight.The percentage error of the approach was determined by applying the formula: percentage error = (x / A) x 100, where x represents the inaccuracy in grams and A represents the actual birth weight.The clinical and ultrasonographic fetal weights were compared to the actual weights, and statistical analysis was conducted using the trial version of SPSS software and MS EXCEL 2007. The descriptive statistics were reported as the mean plus the standard deviation (SD) and as percentages. Karl Pearson's work on correlation the coefficient of correlation is used to determine the correlation between variables. Statistical analyses evaluated p-values less than 0.05 as statistically significant.

Table 1 illustrates the distribution of subjects by gestational age, revealing that the majority of females are at 39-40 weeks of pregnancy, constituting 58% of the total sample. Following closely behind, 36% of the subjects are at 37-38 weeks gestation, while only a minority, comprising 6%, are beyond 40 weeks. This distribution suggests a concentration of pregnancies around full term, with fewer instances either preceding or surpassing this range.

Table 2 outlines the distribution of subjects according to the age of the mother, indicating that the majority, at 58%, fall within the 20-25 years age bracket. Following this, 30% of the subjects are between 26-30 years old, while a smaller portion, comprising 12%, are aged 30-35 years. This distribution highlights a predominant concentration of mothers in the younger age groups, particularly within the 20-25 years range.

Table 3 presents the distribution of subjects based on their parity, indicating that 45% of the pregnant individuals are primigravida (first-time mothers), followed by 33% who are 2nd gravida, 15% 3rd gravida, and 7% 4th gravida. This distribution underscores a notable representation of first-time mothers among the sample, with decreasing proportions observed among those with higher gravidity.

Table 4 delineates the distribution of subjects based on the birth weight of their babies, revealing that the most prevalent category is 2.6-3.0 kg, encompassing 41% of the total sample. Following this, 30% of the subjects have babies weighing 3.1-3.5 kg, while 19% fall within the 2.1-2.5 kg range. Additionally, smaller proportions are observed for babies weighing 3.6-4.0 kg (7%) and 1.5-2.0 kg (3%). This distribution signifies a predominant concentration of newborns within the normal birth weight range of 2.6-3.5 kg, with fewer instances of low or high birth weights.

Table 5 presents the distribution of subjects based on the mean birth weight predicted by Hadlock's and Dare's formulae alongside the actual mean weight in kilograms. Hadlock's formula predicts a mean birth weight of 2.92 kg, with a median of 2.92 kg, standard deviation of 0.39 kg, and ranging from 1.50 kg to 3.80 kg. Conversely, Dare's formula yields a slightly higher mean birth weight of 3.06 kg, with a median of 3.14 kg, standard deviation of 0.45 kg, and ranging from 1.69 kg to 3.89 kg. In comparison, the actual mean birth weight observed is 3.02 kg, with a median of 3.04 kg, standard deviation of 0.49 kg, and ranging from 1.60 kg to 3.80 kg. This comparison suggests that both formulas provide relatively close predictions to the actual birth weight, with Dare's formula slightly overestimating compared to Hadlock's, yet both demonstrating reasonably accurate estimates.

Table 6 displays the distribution of subjects based on their Body Mass Index (BMI). Among the sample, 5.7% of individuals have a BMI less than 18.5 kg/m², while the majority, constituting 35.7%, fall within the 18.5-22.9 kg/m² range. Additionally, 25.7% of subjects have a BMI between 23 and 24.9 kg/m², while 32.8% have a BMI greater than 25 kg/m². This distribution indicates a varied representation across different BMI categories, with a significant portion of the sample falling within the normal weight range, but notable proportions also in the overweight and underweight categories.

Table 7 presents the assessment of the correlation between actual birth weight and birth weight predicted by various methods. Hadlock's formula demonstrates a significant correlation with actual birth weight, with r-values ranging from 0.74 to 0.72 across different birth weight categories, all with associated p-values of less than 0.01. Similarly, Dare's formula also exhibits a strong correlation with actual birth weight, with r-values ranging from 0.82 to 0.77 and associated p-values of less than 0.01 across different birth weight categories. These results suggest that both Hadlock's and Dare's formulas are highly correlated with actual birth weight, indicating their efficacy as predictors in estimating birth weight.

The birth weight of an infant significantly influences the occurrence of health issues during the pregnancy and neonatal stages. Intrauterine growth restriction and macrosomic fetuses are associated with long-term neurologic and developmental problems, as well as an increased risk of neonatal morbidity and mortality. Delivery is recommended at 37 weeks of pregnancy when there is intrauterine growth restriction in order to reduce the risk of fetal mortality. Similarly, when macrosomia is diagnosed, a caesarean section is frequently performed to mitigate the potential complications associated with a botched vaginal delivery and shoulder dystocia. [11]
Additional unconventional sonographic parameters employed include the measurement of soft tissue thickness in the humeral region and the distance between the cheeks. Nonstandard measurements do not enhance the efficacy of sonography in predicting birth weight, particularly in exceptional circumstances like diabetic moms.[12] The presence of an anterior placenta, maternal obesity, and oligohydramnios are all factors that can limit the accuracy of sonographic fetal weight estimates. Additional disadvantages of ultrasonography include its intricacy and demanding nature, as well as its restricted visualization of fetal components. During standard obstetric practice, the clinical examination involves measuring the symphysio-fundal height at each antenatal appointment, as demonstrated in a study conducted by Ingale A et al. [12] In this study, we conducted a prospective comparison of clinical and sonographic methods for predicting fetal weight at term. Our findings indicate that the clinical approach is equally accurate to the ultrasonographic approaches, which aligns with the results reported by Dare et al., Avirupa Guha Roy et al, [13], and Ingale A et al. [12] Ultrasonography is now widely accepted as the preferred method for measuring the weight of a fetus in most medical facilities. The formulas developed by Johnson and Dawn for determining clinical birth weight are no longer in use. Due to the limited availability of ultrasound in economically disadvantaged countries like ours, it is important to consider affordability before recommending this investigation. In such cases, clinical birth weight estimation can serve as an alternative tool to identify patients who are at risk of pregnancy-related complications. Hadlock's model predicts that 75% of the newborns would have a weight ranging from 2.5 to 4 kilograms, and only one baby is likely to weigh more than 2.5 kilograms. It indicates a weight that is slightly below the mean.

Previous research has confirmed that ultrasound has a tendency to overestimate lower birth weight categories and underestimate higher birth weight categories when compared to actual birth weight (ABW). In the current investigation, Dare's and Hadlock's equations predicted mean birth weights of 3.07 and 2.90kg, respectively. However, the p-value of 0.45 indicates that these results are not statistically significant. The average actual birth weight was 3.01kg.
The formulas developed by Dare and Hadlock demonstrate a robust correlation with actual birth weight across all weight ranges (r = 0.77 and 0.72; p < 0.05 for both). The highest level of linkage is shown at a birth weight of 100 pounds. The current study found that Dare's formula had a mean error of -2.09% in predicting birth weight, while Hadlock's formula had a mean error of -3.56%. When measured in grams, Dare's formula had a mean error of 60.0 gm, while Hadlock's formula had a mean error of -111.0 gm. This demonstrates that formulas based on ultrasonography (USG) tend to estimate fetal weight on the lower end, whereas clinical formulas tend to slightly overestimate it.
This study exclusively utilized Dare's algorithm for clinical fetal weight assessment.
A bigger sample size with a multicentric investigation would be more appropriate for identifying the true diagnostic value of clinical and ultrasound weight assessment, as the current study was limited by its modest sample size and focus on only one hospital. Because there were just a few underweight and macrosomic neonates included in this study, it was not possible to determine the diagnostic accuracy for detecting underweight and macrosomic fetuses. The primary discovery of the study is that clinical fetal weight assessment is equally precise as ultrasonographic foetal weight estimation within the range of typical birth weights. The significance of our findings lies in the limited accessibility of ultrasound technology in healthcare systems of developing nations, such as ours, especially in rural regions.

Our findings imply that clinical assessment of birth weight can be used as a diagnostic tool, and that clinical estimation is sufficient for managing labour and delivery in a term pregnancy. Except with low-birth-weight newborns, clinical birth weight assessment may be as accurate as regular ultrasonographic measurement. As a result, if the clinical method indicates a weight less than 2,500 g, further sonographic estimation is recommended to provide a more accurate prediction and to assess fetal well-being. Recommendation that all health care personnel be taught how to estimate fetal weight as a normal screening protocol for all pregnant women

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