Zona pellucida thickness variation and occurrence of visible mononucleated blastomers in preembryos are associated with a high pregnancy rate in IVF treatment.
OBJECTIVE
The ability of six morphological criteria (embryo development rate, fragmentation, regularity of blastomere shape, equality of blastomere size, zona pellucida thickness variation [ZPTV], and visible mononucleated blastomeres [VMBs]) to predict pregnancy in IVF treatment cycles was evaluated.


METHODS
In order to select a homogeneous study group, 85 consecutive nulliparous couples with single tubal infertility undergoing their first IVF treatment and receiving three preembryos at embryo replacement 2 days after ovum pickup were included.


RESULTS
A total of 255 preembryos was replaced two days after ovum pickup and resulted in 34 clinical pregnancies (40%). By logistic regression analysis, ZPTV and VMBs showed highly significant and strong predictive values, whereas none of the other parameters was a significant predictor of pregnancy. In the treatments in which all replaced preembryos had a ZPTV of less than 15%, the pregnancy rate was extremely low (1/22). If the maximum ZPTV of any of the replaced preembryos was in the interval between 15 and 20%, the pregnancy rate was 24.1% (7129). In the treatments in which at least one preembryo had a ZPTV of more than 20%, the pregnancy rate was 76.5% (26/34). When VMBs were added to the results of the ZPTV analysis, the pregnancy rate was as high as 92.3% (24/26).


CONCLUSIONS
ZPTV and VMBs seem to be strong predictors of pregnancy in IVF treatment and thus important indicators of good embryo quality.
Palmstierna
M
M
Department of Woman and Child Health, Karolinska Hospital, Stockholm, Sweden.
Murkes
D
D
Csemiczky
G
G
Andersson
O
O
Wramsby
H
H
D000328:Adult; D001757:Blastomeres / Q000502:physiology* / Q000648:ultrastructure; D004624:Embryo Transfer; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D016015:Logistic Models; D008297:Male; D008858:Microscopy, Phase-Contrast; D006080:Ovarian Follicle / Q000000981:diagnostic imaging / Q000502:physiology; D011237:Predictive Value of Tests; D011247:Pregnancy; D018873:Pregnancy Rate; D011786:Quality Control; D016896:Treatment Outcome; D014463:Ultrasonography; D014743:Videotape Recording; D015044:Zona Pellucida / Q000502:physiology* / Q000648:ultrastructure