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Gestational Age Terminology
Excerpt from NICI-net posting on 10/11/2000 by
Dr. Catherine Partyka,
Division of Neonatology, Sinai Hospital of Baltimore. Reprinted here with permission.
"Please, I beg of the community to standardize its language regarding gestational age.
POST-MENSTRUAL AGE (PMA) is the gestational age at birth we are most familiar with, dated by the mother's last LMP. (e.g. this is a 850g 27 3/7 week female....)
CORRECTED GESTATIONAL AGE (CGA) is the PMA plus weeks after birth. (e.g. the afore-mentioned 27 weeker is 31+ weeks CGA at 4 weeks of age).
POST-CONCEPTIONAL AGE (PCA) is the weeks post conception. As you remember, this occurs two weeks after the LMP. Therefore, a term PCA is 38 weeks. The only real use for this term is with IVF babies! In fact one must add two weeks gestation to the date of fertilization to come up with the familiar PMA that we all use. People use this term all the time without realizing the difference, OR to make their BPD, or LOS data look sneakily better. READ the methods. (i.e. discharge or no BPD at 36 weeks PCA looks better than at 38 wks CGA (PMA + postnatal age). They are THE SAME)."
Comment. I must admit that I am among those who have misused these terms. In particular, I have been guilty of using Corrected Gestational Age (CGA) and Post-Conceptional Age (PCA) interchangeably. As Dr. Partyka so clearly points out, the PCA should be 2 weeks less than the CGA. It seems like a small point, but as we embark on our statewide outcomes data collection project, it is important that we are all using uniform data guidelines. Please note that our proposed outcomes data collection form uses CGA (EGA + PNA) to report oxygen dependency at 36 weeks corrected age.
Andrew B. Kairalla MD