Embryonic growth discordance is a term given to a twin growth discordance occurring during the early embryonic period. It is principally manifested by a discrepancy in crown rump length. It is considered independent of the chorionicity of the twins 5.
Embryonic growth discordance can be a relatively common finding in early twin pregnancies with the mean discrepancy according to one study at around 3-4%.
Many associations have been described which include:
- major growth delay of one twin: later in the course of the pregnancy 2
- aneuploidy 2
- loss of one fetus 6
- for milder degrees of discrepancy some authors suggest the CRL of the smaller fetus being a more accurate estimate of the actual gestational age.
- in the absence of aneuploidy or structural fetal abnormality, a recent study has suggested CRL discordance having a poor predictive value for adverse perinatal outcome in both monochorionic and dichorionic twin pregnancies; the CRL discordance is not recommended to identify twin pregnancies at high risk of adverse perinatal outcome 4
- 1. Bhide A, Sankaran S, Sairam S et-al. Relationship of intertwin crown-rump length discrepancy to chorionicity, fetal demise and birth-weight discordance. Ultrasound Obstet Gynecol. 2009;34 (2): 131-5. doi:10.1002/uog.6396 - Pubmed citation
- 2. Salomon LJ, Cavicchioni O, Bernard JP et-al. Growth discrepancy in twins in the first trimester of pregnancy. Ultrasound Obstet Gynecol. 2005;26 (5): 512-6. doi:10.1002/uog.1966 - Pubmed citation
- 3. D'Antonio F, Khalil A, Mantovani E et-al. Embryonic growth discordance and early fetal loss: the STORK multiple pregnancy cohort and systematic review. Hum. Reprod. 2013;28 (10): 2621-7. doi:10.1093/humrep/det277 - Pubmed citation
- 4. D'Antonio F, Khalil A, Dias T et-al. Crown-rump length discordance and adverse perinatal outcome in twins: analysis of the Southwest Thames Obstetric Research Collaborative (STORK) multiple pregnancy cohort. Ultrasound Obstet Gynecol. 2013;41 (6): 621-6. doi:10.1002/uog.12430 - Pubmed citation
- 5. Dias T, Bhide A, Thilaganathan B. Early pregnancy growth and pregnancy outcome in twin pregnancies. Ceylon Med J. 2010;55 (3): 80-4. Pubmed citation
- 6. Bora SA, Bourne T, Bottomley C et-al. Twin growth discrepancy in early pregnancy. Ultrasound Obstet Gynecol. 2009;34 (1): 38-42. doi:10.1002/uog.6422 - Pubmed citation
- 7. Bhide A, Sankaran S, Sairam S et-al. Relationship of intertwin crown-rump length discrepancy to chorionicity, fetal demise and birth-weight discordance. Ultrasound Obstet Gynecol. 2009;34 (2): 131-5. doi:10.1002/uog.6396 - Pubmed citation