Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Oct 1;146(4):515-523.
doi: 10.1097/AOG.0000000000006031. Epub 2025 Aug 14.

Dating Discrepancies on Research Ultrasonography and Risk of Pregnancy Loss in a Prospective Cohort

Alexandra C Sundermann  1 , Elizabeth A Jasper, Suchita E Kumar, Katherine E Hartmann, Digna R Velez Edwards
Affiliations

Dating Discrepancies on Research Ultrasonography and Risk of Pregnancy Loss in a Prospective Cohort

Alexandra C Sundermann et al. Obstet Gynecol. .

Abstract

Objective: To estimate the risk associated with discrepancies between last menstrual period (LMP)-based and ultrasound-based gestational dating and pregnancy loss in a prospective cohort of individuals of normal fertility who underwent standardized early-pregnancy ultrasonography.

Methods: Participants in a community-based, prospective pregnancy cohort were recruited preconceptionally or in early pregnancy. Participants underwent standardized research ultrasonography targeted for the sixth week of gestation. We calculated the magnitude of lag between ultrasound-based age and LMP-based age at the research ultrasonogram. Cox proportional-hazards models were used to estimate the association between this difference and pregnancy loss. To assess for effect modification, analyses were stratified by week of research ultrasonogram, developmental features observed on the ultrasonogram, and menstrual regularity.

Results: Among 4,935 participants, the median difference between LMP-based and ultrasound-based gestational age on the research ultrasonogram was 1 day (interquartile range -1 to 5 days), and 9.3% of pregnancies ended in loss. Risk of pregnancy loss increased exponentially with each additional day ultrasound-based dating lagged LMP-based dating ( P <.001). This association persisted when stratified by week of ultrasonography and was more pronounced among pregnancies with a measurable crown-rump length. Ultrasound-based gestational age lagging LMP-based gestational age by more than 3 days was associated with a fivefold increased risk of pregnancy loss (adjusted hazard ratio [HR] 5.34, 95% CI, 4.37-6.52), and a lag of more than 5 days was associated with a greater than sixfold increased risk (adjusted HR 6.99, 95% CI, 5.78-8.44). These findings persisted when analyses were restricted to individuals with regular cycles and certain LMP dates.

Conclusion: Increasing lag between ultrasound-based dating and LMP-based dating among asymptomatic patients was strongly associated with pregnancy loss risk. This clinically quantifiable measure can inform concern for pregnancy loss before symptom onset among individuals with a certain LMP.

PubMed Disclaimer

Conflict of interest statement

Financial Disclosure The authors did not report any potential conflicts of interest.

Figures

Figure 1.
Figure 1.
Distribution of difference between last menstrual period (LMP)-based and ultrasound-based gestational dating at first-trimester research ultrasound in the entire cohort (A) and stratified by pregnancy outcome (B). Positive values indicate differences in dating such that ultrasound-based gestational age lags LMP-based gestational age and negative values indicate difference in dating such that ultrasound-based gestational age is ahead of LMP-based gestational age (n=4,935).
Figure 2.
Figure 2.
The association between the magnitude of lag between ultrasound-based gestational age compared to last menstrual period (LMP)-based gestational age in days and pregnancy loss. Discrepancy modeled using restricted cubic splines, trimmed to observations where ultrasound-based dating lags LMP-based dating by fourteen days or less and adjusted for gestational age at study ultrasound (n=4,614).
See this image and copyright information in PMC

References

    1. Wilcox AJ, Weinberg CR, O’Connor JF, Baird DD, Schlatterer JP, Canfield RE, et al. Incidence of early loss of pregnancy. New Engl J Med 1988;319:189–94. doi: 10.1056/nejm198807283190401 - DOI - PubMed
    1. Wegienka G, Baird DD. A Comparison of Recalled Date of Last Menstrual Period with Prospectively Recorded Dates. J Womens Health 2005;14:248–52. doi: 10.1089/jwh.2005.14.248 - DOI - PubMed
    1. Hoffman CS, Messer LC, Mendola P, Savitz DA, Herring AH, Hartmann KE. Comparison of gestational age at birth based on last menstrual period and ultrasound during the first trimester. Paediatr Perinat Epidemiol 2008;22:587–96. doi: 10.1111/j.1365-3016.2008.00965 - DOI - PubMed
    1. Savitz DA, Terry JW, Dole N, Thorp JM, Siega-Riz AM, Herring AH. Comparison of pregnancy dating by last menstrual period, ultrasound scanning, and their combination. Am J Obstet Gynecol 2002;187:1660–6. doi: 10.1067/mob.2002.127601 - DOI - PubMed
    1. Committee Opinion No 700: Methods for Estimating the Due Date. Obstet Gynecol 2017;129:e150–4. doi: 10.1097/aog.0000000000002046 - DOI - PubMed