Background
The Intergrowth‐21st (IG) project proposed prescriptive fetal growth standards for global use based on ultrasound measurements from a multicounty study of low‐risk pregnancies selected ...using strict criteria. We examined whether the IG standards are appropriate for fetal growth monitoring in France and whether potential differences could be due to IG criteria for “healthy” pregnancies.
Method
We analysed data on femur length and abdominal circumference at the second and/or the third recommended ultrasound examination from 14 607 singleton pregnancies from the Elfe national birth cohort. We compared concordance of centile thresholds using the IG standards and current French references and used restricted cubic splines to plot z‐scores by gestational age. A “healthy pregnancy” sub‐sample was created based on maternal and pregnancy selection criteria, as specified by IG.
Results
Mean gestational age‐specific z‐scores for femur length and abdominal circumference using French references fluctuated around 0 (−0.2 to 0.1), while those based on IG standards were higher (0.3‐0.8). Using IG standards, 2.5% and 5.2% of fetuses at the third ultrasound were <10th centile for femur length and abdominal circumference, respectively, and 31.5% and 16.7% were >90th. Only 34% of pregnancies fulfilled IG low‐risk criteria, but sub‐analyses yielded very similar results.
Conclusion
Intergrowth standards differed from fetal biometric measures in France, including among low‐risk pregnancies selected to replicate IG's healthy pregnancy sample. These results challenge the project's assumption that careful constitution of a low‐risk population makes it possible to describe normative fetal growth across populations.
These clinical practice guidelines from the French National College of Midwives (CNSF) are intended to define the messages and the preventive interventions to be provided to women and co‐parents by ...the different professionals providing care to women or their children during the perinatal period. These guidelines are divided into 10 sections, corresponding to 4 themes: 1/ the adaptation of maternal behaviors (physical activity, psychoactive agents); 2/ dietary behaviors; 3/ household exposure to toxic substances (household uses, cosmetics); 4/ promotion of child health (breastfeeding, attachment and bonding, screen use, sudden unexplained infant death, and shaken baby syndrome). We suggest a ranking to prioritize the different preventive messages for each period, to take into account professionals’ time constraints.
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