Table 4. Best-fit regression coefficients and standard error for the three groups of variables.

Embryonic day	model	Set of parameters	Coefficient	Standard error	p
E7.5–E9.5	Group 1	Implantation site length	0,1343	0,05011	0,0092
		Gestational sac thickness	0,1853	0,07057	0,0107
		Gestational sac length	0,4520	0,06622	<0,0001
		Crown-rump length (CRL)	0,4988	0,1061	<0,0001
		Constant	6,3475
E9.5–E11.5	Group 2	Gestational sac thickness	0,1270	0,03938	0,0022
		Gestational sac length	0,07384	0,02222	0,0016
		Placental length	0,2023	0,05277	0,0003
		Biparietal diameter	0,2534	0,08666	0,0051
		Crown-rump length (CRL)	0,2066	0,02376	<0,0001
		Constant	7,9073
E12.5–E16.5	Group 3	Biparietal diameter	0,7009	0,1206
		Occipital snout length	0,1444	0,06992
		Antero-posterior lens diameter	1,5952	0,6204
		Stomach diameter	1,2595	0,4298
		Antero-posterior abdominal diameter	0,4805	0,08862
		Constant	6,7749