Fetal macrosomia; risk factors and validity of its diagnostic tools

INTRODUCTION

Macrosomia, defined as a birth weight of 4000 g or above, is one of the most frequent prenatal problems.

Depending on demographic factors and diagnostic criteria employed, macrosomia is predicted to afflict 0.9–12% of all pregnancies ¹.

It is linked to a significantly increased risk of negative health consequences in both mothers and children.

For example, the majority of researches have shown that being born big is linked to both immediate and long-term health concerns for both the baby and the mother ^2.

When the head size, belly circumference, and weight surpass the 90th percentile for the gestational age, macrosomia may be symmetric in post-term pregnancy or owing to hereditary causes. It was discovered that undiagnosed women with hyperglycemia birth 80 percent of macrosomic infants ^3.

Excessive prenatal weight gain, poorly managed diabetes, and maternal obesity all result in foetal hyperglycemia, which stimulates foetal insulin release, insulin-like growth factors, and other growth factors and growth hormones. The foetal adipose tissue is more plentiful, the liver has more glycogen,

and intrauterine development is accelerated as a result of hyperinsulinemia ^4.

Studies of obese mothers' siblings born before and after bariatric surgery found that birth weight dropped when maternal BMI fell, and their genetic expression was different, indicating improvement in infants after surgery ^5.

Because of the maternal, foetal, and neonatal consequences of macrosomia, pregnant women who are at risk should be counselled and monitored to follow a low-calorie, low-glycemic diet and avoid sedentary activity.

Because of the risk of obesity, diabetes, hypertension, and metabolic syndrome later in life, the mother and the macrosomic infant must be followed for a long time. Because prenatal foetal weight assessment is not always reliable, particularly in foetuses with macrosomia, this research will be conducted to determine the prevalence and predictability of foetal macrosomia.

The goal of this research was to see how often foetal macrosomia was at AL-Azhar University Hospital (Assuit). At addition, we wanted to see how accurate clinical assessment and 2D ultrasound examination were in predicting foetal macrosomia in the AL-Azhar University Hospital (Assuit). 

PATIENTS AND METHODS

The present study was carried out in the Obstetrics and Gynecology department, in Al-Azhar (Assuit) University Hospital from May to October 2020. Ethical permission was sought from a Local Research Ethics Committee (REC) in the department. The patients were given a full and clear explanation about the study.

Cross sectional observational study; Antenatal diagnosis of fetal macrosomia (more than 4kg) was compared with neonatal pondal status to assess accuracy of clinical evaluation and ultrasound examination in diagnosis of these cases.

Inclusion criteria: All pregnant females who were admitted to our hospital and were delivered by CS indicated by prenatal diagnosis of fetal macrosomia.

Exclusion criteria:

 All macrosomic babies caused by congenital fetal malformation such as hydrocephalus, fetal hydrops.

 Multiple pregnancies.

Other obstetric indication of CS.

Abdominal and obstetric examination

Leopold's tactics were utilized by the examiners.

The symphysis-fundal height (SFH) was measured from the mid-point of the maternal pubic symphysis upper border to the highest point on the uterine fundus.

The umbilicus was used to measure the mother's belly circumference.

A flexible tape calibrated in cm was used to collect measurements.

Ultrasound examination

The most frequent technique of examining pregnant women is two-dimensional ultrasonography.

Using particular growth curves, indices, and formulae with varying degrees of sensitivity and specificity, the diagnosis of foetal macrosomia must be linked to the clinical condition.

Unfortunately, as foetal weight rises, so does the number of mistakes.

Two-dimensional ultrasonography was used to evaluate foetal weight, with a single sonographer assessing Bi Parietal Diameter (BPD), Head Circumference (HC), Abdominal Circumference (AC), and Femur Length (FL) before calculating foetal weight using the Hadlock method.

Details of pregnancy outcome were recorded in the form of:

Group A: females who delivered by CS indicated by fetal macrosomia and postnatal evaluation of baby approve our prenatal diagnosis.

Group B: females who delivered by CS indicated by fetal macrosomia, but postnatal evaluation of baby conflict our prenatal diagnosis.

Data analysis:

SPSS (Geometric set for societal skills) version 20 stood castoff during study. Standard t-tests or the Mann-Witney U tests were used for comparison of factors influencing perinatal mortality and different modalities of management.

RESULTS

Through the training retro from May to October 2020, there were a total of 3850 deliveries by Caesarean section 208 were due to macrosomia (took a mass larger than or like to 4000 g clinically and by US) . The prevalence of fetal macrosomia was 5.5%.

Demographic facts of 208 females involved in the training are exposed in (Table 1). The willful females took an age of 31.63±4.97 eons (19-42), Parity of 3.45±1.75 deliveries (1-8), A gestational age 40.05±1.63 weeks, Most of them were postdate. A BMI (kg/m2) 31.98±5.28, Most of them were overweight (84.6%). Most of them had a previous history of fetal macrosomia (71.6%). by routine screening of DM most of studied women are diabetic (69.2%). Most of studied women were Rural and House worker. Maternal and fetal characteristics and pregnancy outcomes obtained from CS indicated by prenatal diagnosis of fetal macrosomia according to actual fetal weight (weight after birth)

Table 1: Demographic data of studied sample (n=208)

There was a sturdy overtone amid fetal macrosomia and caring age bigger than 30 years 135(81.3%) and high parity134 (80.7%), advanced maternal age and high parity should be considered as important risk factors for macrosomia (Table 2).

Table 2: Association between maternal age, parity and fetal macrosomia

Lying-in length superior than 40 weeks was also knowingly allied with fetal macrosomia, 134 (80.7%) of macrosomic cases are postdate (Table 3).

Table 3: Association between gestational age and fetal macrosomia

Fetal macrosomia can be due to superior parental BMI at the time of start, extreme mass gain among conditions in addition to heft advance thru lying-in 135(81.3%) (Table 4).

Table 4: Maternal Obesity and Occurrence of Fetal Macrosomia

Maternal hyperglycemia should be considered a strong predictor of fetal macrosomia. A past of diabetes mellitus (pre-current or gestational) befell more often mid the bags, 111(86.7%) cases of macrosomic baby were of diabetic mother (Table 5).

Table 5: Association between diabetes mellitus and macrosomia

Previous history of macrosomia likely contributes to macrosomia 120(72.3%). The tall manly to girlish percentage in the macrosomic set was stated 131(78.9%) but polyhydraminos not frequently associated with fetal macrosomia (46.4%) (Table 6).

Table 6: Other determinants and risk factors of fetal macrosomia

Cruel utter fault (gm)= weight clinically or by US – AFW(weight after birth) Mean error percentages = Mean absolute error (gm) X 100/ AFW(weight after birth). When comparing absolute mean error at various gestational ages and absolute error > 500g between clinical and ultrasound techniques, the clinical approach had substantially greater absolute mean error at different gestational ages (Table 7).

Table 7: Comparison between clinical and ultrasound methods in weight estimations regarding mean absolute error and mean error percentages, absolute mean error at different gestational ages and error percentages

The importance of clinical and ultrasound EFW determinations in predicting actual foetal weight > 4000 gm is shown in (Table 8). Ultrasound EFW showed a greater sensitivity and a higher AUC (0.781) and higher predictive values.PPV(72.5%) NPV (83.75%).

Table 8: ROC curve of value of clinical and ultrasound EFW determination in predicting actual fetal weight > 4000 gm.

In any absolute error estimates of normal weight women giving delivery, there was no statistically significant difference in the accuracy of foetal weight estimation done using Leopold's manoeuvres vs ultrasonography. At the moment of delivery registration, this may be shown in (Table 9).

Table 9: Accuracy of both weight estimations regarding effective birth weight in all normal weight pregnant women (n=32)

In all absolute error estimates conducted in overweight women giving delivery, there was a statistically significant difference in the accuracy of foetal weight estimation in favour of ultrasonography. At the moment of delivery registration, this may be seen in (Table 10) .

Table 10: Accuracy of both weight estimations regarding effective birth weight in overweight and obese pregnant women (n=176)

A statistically major change in the truth of fetal bulk estimate was observed in all absolute error calculations clinically and by US in diabetic and non diabetic women with higher absolute error in diabetic women especially in clinical estimation of fetal weight (Table 11& 12).

Table 11: Accuracy of both weight estimations regarding effective birth weight in diabetic pregnant women (n=144)

Table 12: Accuracy of both weight estimations regarding effective birth weight in non-diabetic pregnant women (n=64)