by: Dr. Sung Tae Kim, PhD, HCLD (ABB) Laboratory Director 

Can transferring multiple embryos really increase the chance of pregnancy?

We analyzed 191 cases of IVF patients using their own eggs and 65 cases of IVF patients using donor eggs from 2016 to July 2017. As you can see, the pregnancy rate does not vary significantly based on the number of embryos transferred. However, the risk of multiples is significantly higher for those women who used donor eggs AND transferred two embryos (47.4% vs. 64.9%).


IVF Patients Who Used Their Own Eggs & Are Under 38 Years Old IVF Patients Who Used Donor Eggs                      
# embryos transferred 1 embryo 2 embryos 1 embryo 2 embryos
# of transfer cycles 72 119 18 47
% pregnant 72.2% 75.6% 72.2% 78.7%
% fetal heart beat 88.5% 86.7% 100% 97.3%
% multi heart beat 0 47.4% 0 64.9%


ASRM (American Society for Reproductive Medicine) and SART (Society for Assisted Reproductive Technology) strongly recommend single embryo transfer for PGS cases and for women under the age of 38 (Table 1).



Increased complications in a multiple pregnancy

Infants born in multiple births are more often born early (preterm), are smaller (low birth weight), and experience more adverse health outcomes than singleton infants. SET (single embryo transfer) helps women avoid several risks to their own health that are associated with carrying multiples. It also helps families achieve success while preventing some risks known to be associated with giving birth to twins or what is called “high order multiple births” (three or more children born at the same time). There is consensus among experts that the desired outcome of ART (assisted reproductive technology) is a healthy singleton infant.


Singleton Twin Triplet
Ave. month at birth 9 month 8 month 7 month
% Very premature (<7 month) 1.7% 14% 41%
Ave. birth weight 7.4 lbs 5.2 lbs 3.8 lbs
% Severe handicap 1.9% 3.4% 5.7%
% Infant mortality 1.1% 6.6% 19%


How to select one embryo for transfer?

The selection of the best embryo for transfer relies on morphological evaluation with extended culture until day 5 or 6. In addition, PGS (preimplantation genetic screening) helps to select a chromosomally normal embryo (visit previous Blog about PGS).


Carolina Conceptions has a very well established frozen embryo transfer system. There is no difference of pregnancy rate between fresh and frozen embryo transfer in Carolina Conceptions. It is better idea to save your excess embryos for another pregnancy. Our goal is to have a healthy child, not just to be pregnant.



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