The clinical significance of an estimated fetal weight below the 10th percentile: a comparison of outcomes of <5th vs 5th–9th percentile

Malgorzata Mlynarczyk, Suneet P. Chauhan, Hind A. Baydoun, Catherine M. Wilkes, Kimberly R. Earhart, Yili Zhao, Christopher Goodier, Eugene Chang, Nicole M. Lee Plenty, E. Kaitlyn Mize, Michelle Owens, Shilpa Babbar, Dev Maulik, Emily DeFranco, David McKinney, Alfred Z. Abuhamad

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Background The association between small-for-gestational-age (birthweight <10th percentile for gestational age) and neonatal morbidity is well established. Yet, there is a paucity of data on the relationship between suspected small for gestational age (sonographic-estimated fetal weight <10th percentile) at 2 thresholds and subsequent neonatal morbidity. Objective The objective of this study was to determine the relationship between sonographic-estimated fetal weight <5th percentile vs 5–9th percentile and neonatal morbidity. Study Design This retrospective study involved 5 centers and included nonanomalous, singletons with sonographic-estimated fetal weight <10th percentile for gestational age who delivered from 2009–2012. Composite neonatal morbidity included respiratory distress syndrome, proven sepsis, intraventricular hemorrhage grade III or IV, necrotizing enterocolitis, thrombocytopenia, seizures, or death. Odd ratios were adjusted for center, maternal age, race, body mass index at first visit, smoking status, use of alcohol, use of drugs, and neonatal gender. Results Of 834 women with suspected small-for-gestational-age fetuses, 513 (62%) had sonographic-estimated fetal weight <5th percentile, and 321 (38%) had sonographic-estimated fetal weight of 5–9th percentile for gestational age. At delivery, 81% of women with a suspected small-for-gestational-age fetus had a confirmed small-for-gestational-age fetus. In the group with a sonographic-estimated fetal weight <5th percentile, 59% of neonates had birthweight <5th percentile; in the group with a sonographic-estimated fetal weight 5–9th percentile, 41% had birthweight <5th percentile, and 36% had birthweight at 5–9th percentile. Neonatal intensive care unit admission differed significantly for those fetuses at <5th percentile (29%) compared with those fetuses at 5–9th percentile (15%; P<.001). The composite neonatal morbidity among the sonographic-estimated fetal weight <5th percentile group was higher than the sonographic-estimated fetal weight of 5–9th percentile group (31% vs 13%; adjusted odds ratio, 2.41; 95% confidence interval, 1.53–3.80). Similar findings were noted when the analysis was limited to sonographic-estimated fetal weight within 28 days of delivery (adjusted odds ratio, 2.22; 95% confidence interval, 1.34–3.67). Conclusion Eight of 10 suspected small-for-gestational-age fetuses had birthweight <10th percentile for gestational age; the prediction of actual birthweight was more accurate in the <5th percentile group. Neonates with sonographic-estimated fetal weight of <5th percentile were more likely to be admitted to the neonatal intensive care unit and have complications than were those neonates with sonographic-estimated fetal weight of 5–9th percentile.

Original languageEnglish
Pages (from-to)198.e1-198.e11
JournalAmerican Journal of Obstetrics and Gynecology
Issue number2
StatePublished - Aug 2017

Bibliographical note

Publisher Copyright:
© 2017 Elsevier Inc.


  • small for gestational age
  • sonographic-estimated fetal weight

ASJC Scopus subject areas

  • Obstetrics and Gynecology


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