The application of individualised fetal growth curves

First-trimester prediction of macrosomia

OBJECTIVE

To determine if combinations of maternal characteristics and measurements of parameters used in screening for aneuploidies at 11-13 weeks provide significant prediction of macrosomia.

METHOD

Maternal characteristics, fetal nuchal translucency (NT), free β-human chorionic gonadotrophin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A) were recorded at 11(+0)-13(+6) weeks in 36,743 singleton pregnancies. Regression analysis was used to determine if in predicting macrosomia significant contributions are provided by maternal factors, fetal NT, free β-hCG and PAPP-A.

RESULTS

The risk for macrosomia increased with maternal weight and height and was higher in parous women with previous delivery of a macrosomic baby and in those with diabetes mellitus; the risk was lower in women of African and South Asian racial origins, in cigarette smokers and in those with chronic hypertension. In the macrosomic group compared to the unaffected group there were higher Δ-NT (0.167 vs. 0.116 mm), free β-hCG (1.010 vs. 0.964 MoM) and PAPP-A (1.103 vs. 1.003 MoM). Prediction of macrosomia provided by maternal factors was significantly improved by fetal NT, free β-hCG and PAPP-A (34.4 vs. 33.1% at a false-positive rate of 10%).

CONCLUSION

Prediction of macrosomia is provided in the first trimester of pregnancy by a combination of maternal characteristics and measurements of parameters used in screening for aneuploidies.

The fetus that is small for gestational age

The symmetric small for gestational age (SGA) fetus presents a complex management problem for the obstetrician, but the growth restriction affects morbidity and mortality at all stages of life. The differential diagnosis in symmetric growth aberration includes the constitutionally small fetus, the fetus with pathology, and the cases with incorrect dating of pregnancy. The ultrasonographic examination focuses in the detection of anomalies, signs of intrauterine infection, and serial assessment of fetal growth. Accuracy of fetal biometry may be improved by using individualized fetal growth curves. From the available surveillance tools, the uterine artery Doppler has a value in predicting poor perinatal outcome. Magnetic resonance imaging is also useful in the evaluation of anomalies. Cesarean section is not justified for all symmetric SGA fetuses that may carry a guarded prognosis.

Ethnic variations in birthweight percentiles in Kuwait

The objectives of this retrospective study were to assess the effect of ethnicity on birthweight percentiles and to compare ethnic-specific percentiles with other references. Analysis was made of 35 768 singleton live births from 22 to 44 completed weeks of gestation at two major obstetric hospitals in Kuwait, after exclusion of data with inaccurate gestational age, major congenital abnormalities, stillbirths, and outlying birthweights. The population included four major ethnic groups: Gulf Arabs, Mediterranean Arabs, Egyptians, and a group combining Indians and Southeast Asians. Total population and ethnic-specific smoothed birthweight percentiles according to gestational age were developed. Indians-Asians had the smallest birthweights, the highest prevalence of small-for-gestational-age (SGA) birthweights and the lowest prevalence of large-for-gestational-age (LGA) birthweights. On the contrary, Egyptians had the largest birthweights, the lowest prevalence of SGA birthweights and the highest prevalence of LGA birthweights. Plotting our birthweights on a reference from Canada resulted in a low prediction rate for SGA and a low sensitivity in identifying LGA of all ethnic groups. We conclude that interpretation of fetal growth and birthweight should involve locally derived and ethnically specific percentiles based on accurately calculated gestational age.

Secular trends in neonatal macrosomia in Berlin: influences of potential determinants

To investigate the trend in the prevalence of neonatal macrosomia and to evaluate the influences of potential determinants, key features of 206 308 hospital deliveries (97% of all) in Berlin in the years 1993-99, collected by the Berlin Medical Board, were analysed using SPSS 10.0. After exclusion of multiple births and preterm infants, there was a significant increase over 7 years (P < 0.01) in the prevalence of birthweights >or= 4000 g, maternal age >or= 30 years, height of >or= 165 cm, prepregnancy BMI (body mass index) >or= 26 kg/m2 and pregnancy weight gain> 16 kg, but no substantial trend in the prevalence of recognised diabetes or maternal smoking. The adjusted model (OR [95% CI]) for delivering a newborn >or= 4000 g was statistically significant for post-term delivery (2.56 [2.39, 2.75]), women aged >or= 30 years (1.06 [1.02-1.11]), >or= 165 cm tall (1.94 [1.87,2.01]), multiparae (1.98 [1.91, 2.05]), not smoking in pregnancy (2.03 [1.93, 2.14]), prepregnancy BMI >or= 26 compared with < 20 (4.01 [3.77, 4.26]), pregnancy weight gain >or= 16 kg compared with < 10 kg (3.37.[3.22, 3.53]) and for recognised diabetes (1.85.[1.69, 2.04]). It is speculated that this increase in the prevalence of neonatal macrosomia may contribute to the secular trend of overweight and obesity under affluent living conditions.