Comparison of birth weights in patients randomly assigned to fresh or frozen-thawed embryo transfer

Fertil Steril. 2016 Aug;106(2):317-21. doi: 10.1016/j.fertnstert.2016.03.049. Epub 2016 Jul 7.

Abstract

Objective: To estimate birth weight differences between patients randomized to fresh or thawed ET.

Design: Post hoc analysis of results from two similar randomized trials.

Setting: Private fertility center.

Patient(s): One hundred thirty-four first-time IVF patients, ages 18-40 years at oocyte retrieval, who had live birth.

Intervention(s): Patients were randomly assigned to have either fresh blastocyst transfer or all bipronuclear oocytes frozen followed by thaw, extended culture, and blastocyst transfer in a subsequent cycle. Preimplantation genetic screening was not allowed.

Main outcome measure(s): Mean birth weight.

Result(s): After allowing for the contributions of multiple significant variables (gestational age at birth, the presence of a vanished twin, number of infants delivered) in multiple linear regression, the adjusted mean birth weight was 166 g (95% confidence interval, 43-290 g) lower after fresh blastocyst transfer when compared with transfer of blastocysts derived from thawed bipronuclear oocytes.

Conclusion(s): Birth weights are lower in cycles with fresh blastocyst transfer after controlled ovarian stimulation than in transfers of frozen-thawed embryos in the absence of ovarian stimulation. This finding confirms similar results reported in many retrospective studies.

Clinical trial registration numbers: NCT00963625 and NCT00963079.

Keywords: Assisted reproduction; birth weight; embryo cryopreservation; ovarian stimulation.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Birth Weight*
  • Blastocyst / physiology*
  • Cryopreservation*
  • Embryo Culture Techniques
  • Embryo Transfer* / adverse effects
  • Female
  • Fertility
  • Fertilization in Vitro* / adverse effects
  • Humans
  • Infant, Newborn
  • Infertility / diagnosis
  • Infertility / physiopathology
  • Infertility / therapy*
  • Live Birth
  • Oocyte Retrieval
  • Ovulation Induction* / adverse effects
  • Pregnancy
  • Pregnancy Rate
  • Risk Factors
  • Treatment Outcome
  • Young Adult

Associated data

  • ClinicalTrials.gov/NCT00963625
  • ClinicalTrials.gov/NCT00963079