PMID- 11775983
OWN - NLM
STAT- MEDLINE
DCOM- 20020201
LR  - 20190822
IS  - 0093-691X (Print)
IS  - 0093-691X (Linking)
VI  - 57
IP  - 1
DP  - 2002 Jan 1
TI  - High rates of embryonic loss, yet high incidence of multiple births in human ART: 
      is this paradoxical?
PG  - 87-96
AB  - Humans have low natural fecundity, as the probability of establishing a viable 
      conception in any one menstrual cycle is 20-25% for a healthy, fertile couple. 
      There are numerous underlying causes for this low rate of human fertility, not 
      the least of which are intrinsic abnormalities within the oocyte and/or embryo, 
      which likely account for greater than 50% of failed conceptions. During assisted 
      reproduction technology (ART) interventions, controlled ovarian stimulation is 
      used to obtain several oocytes in attempts to increase the likelihood of having 
      at least one developmentally competent embryo available for transfer. However, 
      current techniques for identifying the competent embryo(s) are by no means 
      perfect. These limitations, coupled with pressures to maximize the chance of 
      pregnancy, typically result in the transfer of multiple embryos. Not 
      surprisingly, this practice has resulted in an unacceptably high rate of multiple 
      pregnancies arising from ART. During the last few years, concerted efforts have 
      focused on reducing these rates. Programs for ART are developing patient-specific 
      policies, restricting the number of embryos to transfer. In addition, strategies 
      are being adopted to improve the accuracy for selecting viable embryos for 
      transfer. One such strategy involves further refinement of morphological criteria 
      associated with improved viability by considering, for example, pronuclei 
      disposition, nucleolar organization, and identification of the fast-cleaving 
      embryos with only mononucleate blastomeres. Another strategy employs 
      pre-implantation genetic diagnosis (PGD) whereby a biopsied blastomere is tested 
      for ploidy using fluorescence in situ hybridization (FISH). A final strategy 
      involves extending the duration of culture to the blastocyst stage, thereby 
      allowing self-selection of those embryos capable of proceeding to blastulation 
      and exclusion of those less viable embryos that succumb to developmental arrest. 
      Together, these strategies are enabling fewer embryos of higher quality to be 
      transferred. Accordingly, the overall pregnancy rate from ART continues to 
      increase, while the rate of triplet and higher order multiple births continues to 
      decline. Nevertheless, the high incidence of intrinsic developmental anomalies in 
      human oocytes inevitably will continue to result in a high degree of embryonic 
      loss in ART.
FAU - Racowsky, C
AU  - Racowsky C
AD  - Department of Obstetrics, Gynecology and Reproductive Biology, Brigham and 
      Women's Hospital, Harvard Medical School, Boston, MA, USA.
LA  - eng
PT  - Journal Article
PT  - Review
PL  - United States
TA  - Theriogenology
JT  - Theriogenology
JID - 0421510
SB  - IM
MH  - Adult
MH  - Aneuploidy
MH  - *Embryo Transfer/adverse effects/standards
MH  - Embryo, Mammalian/anatomy & histology/*physiology
MH  - Female
MH  - Fertilization in Vitro/*methods
MH  - Humans
MH  - In Situ Hybridization, Fluorescence
MH  - Incidence
MH  - Pregnancy
MH  - Pregnancy Outcome
MH  - Pregnancy, Multiple/*physiology/statistics & numerical data
MH  - Preimplantation Diagnosis
RF  - 52
EDAT- 2002/01/05 10:00
MHDA- 2002/02/02 10:01
CRDT- 2002/01/05 10:00
PHST- 2002/01/05 10:00 [pubmed]
PHST- 2002/02/02 10:01 [medline]
PHST- 2002/01/05 10:00 [entrez]
AID - S0093691X01006598 [pii]
AID - 10.1016/s0093-691x(01)00659-8 [doi]
PST - ppublish
SO  - Theriogenology. 2002 Jan 1;57(1):87-96. doi: 10.1016/s0093-691x(01)00659-8.