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Table 4 Reference values for GSD, YSD, CRL and HR in previous studies and the present study

From: Reference intervals of gestational sac, yolk sac, embryonic length, embryonic heart rate at 6–10 weeks after in vitro fertilization-embryo transfer

Author Studied population Inclusion criteria Scanning method Gestational days
45 55 65
GSD
mm
CRL
mm
YSD
mm
HR
bpm
GSD
mm
CRL
mm
YSD
mm
HR
bpm
GSD
mm
CRL
mm
YSD
mm
HR
bpm
Robinson and Fleming, 1975 [7] (n = 334) Spontaneous No information about outcome TA 6.1 13.8 24.2
Lindsay et al., [21]
1992 (n = 327)
Spontaneous Pregnancy continued ≥ 27 weeks TV 2.7 3.1 3.5
Grisolia et al., [22]
1993 (n = 248)
Spontaneous Normal live birth TV/TA 14.0 7.0 26.0 15.0 38.0 25.0
Britten et al., [23]
1994 (n = 361)
Assisted reproduction Normal live birth TV 123.3 163.0
Yapar et al., [24]
1995 (n = 1331)
No information No information about outcome TV 128.2 161.6 175.1
Coulam et al. [25]
1996 (n = 361)
Assisted reproduction Normal live birth TV 16.0 5.5 123.0 29.0 15.3 163.0
Tannirandorn et al., [2] 2000 (n = 547) Spontaneous Normal live birth TV 147.4 163.9 172.7
McLennan et al., [26]
2008 (n = 396)
Mixed spontaneous + assisted Pregnancy continued ≥ 20 weeks TV/TA 7.0 15.0 26.0
Papaioannou et al. [5] 2010 (n = 4698) Mixed (spontaneous 97.9% + assisted 2.1%) Normal live birth TV 17.4 5.4 3.6 120.0 27.3 14.0 4.2 156.0 37.3 24.6 4.8 174.0
Our study 9
(n = 30,416)
Assisted reproduction Normal live birth TV 19.0 3.4 3.7 117.0 29.0 13.6 4.5 159.0 40.0 24.0 5.0 176.0
  1. GSD gestational sac diamter, CRL crown rump length, YSD yolk sac diameter, HR heart rate, TA, transabdominal, TV transvaginal