Birth weight is associated with inner cell mass grade of blastocysts

Blastocysts with a more developed inner cell mass developed into newborns with a greater weight, when corrected for gestational age and gender.

Frederick Licciardi, M.D., Caroline McCaffrey, Ph.D., Cheongeun Oh, Ph.D., Cecilia Schmidt-Sarosi, M.D., David McCulloh, Ph.D.

Volume 103, Issue 2, Pages 382-387


To determine the relationship between blastocyst growth parameters and birth weight.

Cohort study.

University-affiliated fertility center.

In vitro patients who delivered a singleton after a single-blastocyst transfer.


Main Outcome Measure(s):
Birth weight adjusted for gestational age at delivery and gender, with adjusted birth weight examined for association with blastocyst scores and grades.

After standard in vitro fertilization (IVF) and thawed embryo transfers, greater birth weight was associated with a higher inner cell mass grade. The grade of the trophectoderm and stage of the blastocyst did not relate to weight.

Embryonic growth as early as day 5 can predict the progress of fetal development as measured by birth weight.

  • Shvetha Zarek

    This study is the first to evaluate for an association between ICM and birthweight and was well designed by only evaluating single embryo transfers that resulted in a singleton live birth. Overall, it is reassuring that the mean birth weights stratified by ICM grade A, B and C differed only by 143-182 grams. As the authors correctly acknowledge, these initial findings will need to be confirmed in a larger study with higher proportions of grade A and C blastocysts. In addition, as the authors state, birth weight analysis generally also takes into account covariates like maternal age, maternal BMI, gestational weight gain, parity, and medical conditions that were not available in this data set. Thank you to the esteemed authors for evaluating an important clinical question!

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