Table 1.

Demographic description of subjects

	Males			Females			Total
Age group	N	Age mean, days	Age st. dev, days	N	Age mean, days	Age st. dev, days	N
1 month	97	46.5	9.6	102	47.2	9.8	199
6 month	385	197.8	14.1	363	194.5	11.9	748
10 month	337	313.4	13.1	317	315	13.2	654