Comparison of Naturally Conceived and IVF-DZ Twins in the Netherlands Twin Registry: A Developmental Study

Table 3

Mean and standard deviation (SD) of ages (months) at which motor milestones are attained for IVF/ICSI twins and matched NC twins.

	IVF/ICSI twins			Matched NC twins			𝑃 *
	𝑁	Mean	(SD)	𝑁	Mean	(SD)
Turning	2535	6.3	(1.7)	2473	6.4	(1.8)	0.870
Sitting	2553	8.7	(1.8)	2501	8.9	(1.8)	0.008
Crawling	2296	9.7	(1.7)	2244	9.7	(1.7)	0.448
Standing alone	2533	12.2	(2.4)	2470	12.5	(2.6)	0.003
Walking alone	2632	14.8	(2.4)	2605	15.0	(2.4)	0.002

Note: *𝑃 value based on tests comparing IVF and matched NC groups.