Table 6.

Sample size calculations (to achieve a power of 80% for the primary outcome, assuming a two-sided alpha of 0.05 and different proportions projected with adequate GWG)

Outcome	Proportion in controla	Proportion in experimentalb	N in each group
Weekly weight from baseline to 36 weeks	0.19	0.25	748
	0.19	0.27a	434
	0.19	0.30	239
	0.19	0.35	120
	0.19	0.40	73
Weekly weight from baseline to delivery	0.13	0.27a	127
Total weight from baseline until delivery	0.25	0.40a	152

Notes:

^aProportion with adequate GWG (IOM guidelines) in PEARLS sample.

^bProjected with adequate GWG in PEARLS intervention group.

Abbreviations: GWG, gestational weight gain; IOM, Institute of Medicine; PEARLS, Pregnancy and EARly Lifestyle improvement Study.