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Fertil Steril. 2015 Jan;103(1):95-100. doi: 10.1016/j.fertnstert.2014.10.013. Epub 2014 Nov 5.

Blastocyst transfer is not associated with increased rates of monozygotic twins when controlling for embryo cohort quality.

Author information

1
Division of Reproductive Endocrinology, Department of Obstetrics Gynecology and Reproductive Sciences, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey. Electronic address: jfranasiak@rmanj.com.
2
Winthrop University Hospital, Mineola, New York.
3
Reproductive Medicine Associates of New Jersey, Basking Ridge, New Jersey.
4
Division of Reproductive Endocrinology, Department of Obstetrics Gynecology and Reproductive Sciences, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey; Reproductive Medicine Associates of New Jersey, Basking Ridge, New Jersey.
5
Division of Reproductive Endocrinology, Department of Obstetrics Gynecology and Reproductive Sciences, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey.

Erratum in

  • Fertil Steril. 2015 Mar;103(3):862.

Abstract

OBJECTIVE:

To compare monozygotic twinning (MZT) rates in patients undergoing blastocyst or cleavage-stage ET.

DESIGN:

Retrospective cohort.

SETTING:

Academic research center.

PATIENT(S):

Autologous, fresh IVF cycles resulting in a clinical pregnancy from 1999 to 2014.

INTERVENTION(S):

None.

MAIN OUTCOME MEASURE(S):

Monozygotic twin pregnancy in blastocyst-stage transfer vs. cleavage-stage transfer when controlling for patient prognosis and embryo cohort quality factors.

RESULT(S):

There were a total of 9,969 fresh transfer cycles resulting in a pregnancy during the study period. Of these pregnancies, 234 monozygotic twin pregnancies were identified (2.4%). Of all transfers, 5,191 were cleavage-stage and 4,778 were blastocyst-stage transfers. There were a total of 99 MZT identified in the cleavage-stage group (1.9%) and 135 MZT in the blastocyst ET group (2.4%), which was significant. Multivariable logistic regression revealed that increasing age was associated with a significant reduction in MZT, regardless of transfer order. Embryo cohort quality factors, including the number and proportion of six- to eight-cell embryos and availability of supernumerary embryos, were also significant. When controlling for patient age, time period during which the cycle took place, the number and proportion of six- to eight-cell embryos, and availability of supernumerary embryos, there was no longer a difference in MZT rate between blastocyst and cleavage transfer.

CONCLUSION(S):

Patient prognosis and embryo cohort quality seem to be major factors in MZT rate in women undergoing blastocyst transfer. Although technology-based effects cannot be excluded, patient and embryo characteristics play an important role.

KEYWORDS:

IVF; blastocyst; monozygotic pregnancy; twinning

[Indexed for MEDLINE]

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