Table 1. Timing of body size assessments and numbers of participants, cases, and person-years included in each analysis, by study population.

Body size measure	Cohorta	Year assessedb	No. of participants	No. of cases	No. of person-years
Body fatness at ages 5 and 10 years	NHS	1988	64 876	372	888 845
	NHSII	1989	110 274	131	1 614 085
Body mass index at the age of 18 years	NHS	1980	84 643	581	1 680 079
	NHSII	1989	112 119	136	1 640 636
Height	NHS	1976	110 311	735	2 528 901
	NHSII	1989	113 059	137	1 654 409
Birthweight	NHS	1992	49 321	226	521 364
	NHSII	1991	77 952	88	1 016 804

^aThe Nurses' Health Study (NHS) began in 1976 and had 121 700 participants at enrolment, 30–55 years of age. The Nurses' Health Study II (NHSII) began in 1989 and had 116 609 participants at enrolment, 25–42 years of age.

^bThe year when each body size measure was assessed defined the baseline for that analysis; follow-up was through 31 May 2004 for NHS and 31 May 2005 for NHSII.