Influence of medically assisted reproduction techniques on crown rump length and biochemical markers of trisomy 21 in the first trimester of pregnancy

Capsule:
There is a significant difference between the crown-rump length measured in fetuses conceived by assisted reproduction techniques and fetuses conceived by spontaneous pregnancy, which may be indicative of a difference in early growth.

Authors:
Stéphanie Bonne, M.D., Eric Sauleau, M.D., Ph.D., Nicolas Sananes, M.D., Cherif Akaladios, M.D., Catherine Rongières, M.D., Olivier Pirrello, M.D.

Volume 105, Issue 2, Pages 410-416

Abstract:

Objective:
To determine whether there is a difference between the known gestational age in pregnancies conceived after IVF and the estimated gestational age based on the crump-rump length (CRL) measurement during the first trimester.

Design:
We retrospectively (between 2007 and 2012) studied a cohort of 6,739 patients who underwent ultrasonography between 11 and 13+6 weeks of amenorrhea.

Setting:
All of the ultrasonograms were performed at the Centre Médico-Chirurgical et Obstétrique, Strasbourg, France.

Patient(s):
Group A consisted of 6,621 patients with regular menses whose term was calculated based on the date of their last menstrual period (LMP). Group B consisted of 529 patients whose pregnancies had been achieved by IVF and in whom term was calculated based on the date of fresh or frozen ET.

Intervention(s):
None.

Main Outcome Measure(s):
The gestational age difference was obtained by measuring the CRL (Robinson’s curve) and the gestational age calculated in accordance with the LMP or the ET day was measured in each group.

Result(s):
The gestational age difference was significantly more in group B (2.3 days vs. 0.84 days in group A). We found a significant difference regarding biochemical markers for trisomy 21 to the detriment of group B with a significantly reduced pregnancy-associated protein P-A multiple of median (0.78 vs. 0.92).

Conclusion(s):
There appears to be a small difference in CRL development between spontaneous pregnancies and pregnancies conceived by assisted reproductive technology (ART). Specific ultrasonographic curves for pregnancies conceived by ART would be more relevant and precise. The underlying pathophysiological mechanisms are not very clear and offer possibilities for future research.

  • Jason M. Franasiak

    A very interesting finding. Was there a standard protocol utilized for CRL designation? A single measurement or mean of 3 separate measurements? Do the authors have any similar data on frozen embryo transfer cycles and if so noted any difference in fresh and frozen cycles?

    • Stephanie Bonne

      Thank you for your questions.
      All the CRL measurement have been made by the same medical team. They are used to select the best measurement according usual ultrasound criteria for CRL measurement.
      Gestationnal age difference was similar in fresh and frozen embryo transfer cycles (p=0,67).

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