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Fetal growth in early pregnancy and risk of delivering low birth weight infant: prospective cohort study

BMJ 2007; 334 doi: (Published 19 April 2007) Cite this as: BMJ 2007;334:836
  1. Radek Bukowski, associate professor1,
  2. Gordon C S Smith, professor2,
  3. Fergal D Malone, professor3,
  4. Robert H Ball, associate professor4,
  5. David A Nyberg, director5,
  6. Christine H Comstock, director of fetal imaging6,
  7. Gary D V Hankins, professor1,
  8. Richard L Berkowitz, professor7,
  9. Susan J Gross, associate professor8,
  10. Lorraine Dugoff, associate professor9,
  11. Sabrina D Craigo, professor10,
  12. Ilan E Timor-Tritsch, professor11,
  13. Stephen R Carr, associate professor12,
  14. Honor M Wolfe, associate professor13,
  15. Mary E D'Alton, professor7
  16. for the FASTER Research Consortium
  1. 1Department of Obstetrics and Gynecology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA
  2. 2Department of Obstetrics and Gynaecology, Cambridge University, Cambridge CB2 2SW
  3. 3Department of Obstetrics and Gynaecology, Royal College of Surgeons in Ireland, Rotunda Hospital, Dublin 1, Ireland
  4. 4University of California San Francisco, San Francisco, CA 94143-013, USA
  5. 5Fetal and Women's Center of Arizona, Scottsdale, AZ 85258, USA
  6. 6William Beaumont Hospital, Royal Oak, MI 48073, USA
  7. 7Department of Obstetrics and Gynaecology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
  8. 8Albert Einstein College of Medicine, Department of Obstetrics and Gynecology and Women's Health, Montefiore Medical Center/Albert Einstein College of Medicine, Bronx, NY 10461
  9. 9University of Colorado Health Sciences Center, Denver, CO 80262, USA
  10. 10Tufts University School of Medicine, Boston, MA 02111, USA
  11. 11Division of Ob/Gyn Ultrasound, New York University School of Medicine, New York, NY 10016-9196
  12. 12Brown University School of Medicine, Providence, RI 02905, USA
  13. 13University of North Carolina Medical Center, University of North Carolina, Chapel Hill, NC 27599, USA
  1. Correspondence to: R Bukowski rkbukows{at}
  • Accepted 1 February 2007


Objective To determine if first trimester fetal growth is associated with birth weight, duration of pregnancy, and the risk of delivering a small for gestational age infant.

Design Prospective cohort study of 38 033 pregnancies between 1999 and 2003.

Setting 15 centres representing major regions of the United States.

Participants 976 women from the original cohort who conceived as the result of assisted reproductive technology, had a first trimester ultrasound measurement of fetal crown-rump length, and delivered live singleton infants without evidence of chromosomal or congenital abnormalities. First trimester growth was expressed as the difference between the observed and expected size of the fetus, expressed as equivalence to days of gestational age.

Main outcome measures Birth weight, duration of pregnancy, and risk of delivering a small for gestational age infant.

Results For each one day increase in the observed size of the fetus, birth weight increased by 28.2 (95% confidence interval 14.6 to 41.2) g. The association was substantially attenuated by adjustment for duration of pregnancy (adjusted coefficient 17.1 (6.6 to 27.5) g). Further adjustments for maternal characteristics and complications of pregnancy did not have a significant effect. The risk of delivering a small for gestational age infant decreased with increasing size in the first trimester (odds ratio for a one day increase 0.87, 0.81 to 0.94). The association was not materially affected by adjustment for maternal characteristics or complications of pregnancy.

Conclusion Variation in birth weight may be determined, at least in part, by fetal growth in the first 12 weeks after conception through effects on timing of delivery and fetal growth velocity.


  • Contributors: RB and GCSS conceptualised and designed the study, analysed and interpreted the data, drafted the paper, and approved the version to be published. All authors participated in analysis and interpretation of data, revised the manuscript critically for important intellectual content, and approved the version to be published. RB is the guarantor.

  • Funding: The FASTER trial was supported by grant from the National Institutes of Health and National Institute of Child Health and Human Development (RO1 HD 38625). The funders had no role in study design; data collection and analysis; decision to publish; or preparation, review, and approval of the manuscript.

  • Competing interests: None declared.

  • Ethical approval: Institutional review boards in all centres gave approval.

  • Accepted 1 February 2007
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