Estimation du poids de naissance de fœtus de petit poids (≤2500g) et de gros poids (≥4000g) à partir des données échographiques

Are there specific factors associated with prenatally undiagnosed foetal macrosomia?

OBJECTIVE

Fetal macrosomia is known to increase maternal and neonatal complications, but 20%-50% of the macrosomic fetuses are prenatally undiagnosed. Our objective was to identify specific factors associated with undiagnosed fetal macrosomia in women without diabetes.

METHODS

Retrospective case-control study in a tertiary maternity unit between January 1st and December 31st, 2016. Inclusion of all women delivering after 37 weeks of a single live-born macrosomic infant, i.e., with a birth weight ≥ 90th percentile for gestational age (GA). Women with pre-existing or gestational diabetes were excluded. To identify specific factors associated with undiagnosed foetal macrosomia, we compared risk factors for macrosomia, maternal characteristics, father's body mass index (BMI) and prenatal follow up between two groups depending on whether macrosomia was prenatally diagnosed or not.

RESULTS

Among 428 macrosomic newborns, 224 (52.3 %) were prenatally undiagnosed. Known risk factors for macrosomia, maternal characteristics (such as low socio-economic level, low education level) and father's BMI were similar between the two groups. The prenatal follow up was comparable between the two groups. Ultrasound estimated foetal weight during the 3rd trimester was lower in the undiagnosed macrosomic foetuses compared to diagnosed macrosomic foetuses (2130±279 vs 2445±333, p<0.001).

CONCLUSIONS

No specific factor of undiagnosed macrosomia was identified, and women with prenatally undiagnosed fetal macrosomia had the same risk factors than women with diagnosed macrosomia. Our study suggests that our groups have different growth curves. This hypothesis has yet to be studied.

[Accuracy of ultrasound estimated fetal weight performed by residents at delivery day]

Ultrasound fetal weight estimation (EFW) has become a routine practice in obstetrics with a major impact on obstetrical management.

OBJECTIVES

To evaluate the accuracy of sonographic fetal weight estimations performed by residents in obstetrics at the delivery day and to search parameters influencing this exam.

METHODS

A prospective study performed in 299 patients at 37 weeks of gestation or more, during their delivery day. Ultrasound fetal weight estimations were performed by residents and compared to birth weights (BW). The estimated fetal weight (EFW) was calculated using the formula of Hadlock: Log10 EPF=1,335+0.0316 BIP+0,0457 PA+0,1623 LF-0,0034 PA LF.

RESULTS

Mean absolute difference between EFW and BW was 200g [100-450]. Mean absolute percentage error was 5.71 % [2.7-11.37]. The proportion of the EFW within 10 % of BW was 69.6 %. There was a good correlation between EFW and BW (R=0.79). Obesity and fetal macrosomia had negatively influenced ultrasound performance. For the diagnosis of macrosomia, ultrasound has a sensibility of 38 % and a specificity of 99.59 %.

CONCLUSION

Ultrasound fetal weight estimations performed by residents in the delivery room were as accurate as those performed by experimented sonographers. Thus, the predictive performance remains limited with a low sensitivity in the diagnosis of macrosomia.