. Author manuscript; available in PMC: 2012 Jan 1.

Published in final edited form as: Matern Child Health J. 2011 Jan;15(1):19–28. doi: 10.1007/s10995-009-0557-z

Table 5.

Effect of the Intervention on Improving Pregnancy Outcomes

Pregnancy Outcome	Intervention (n =403)	Usual Care (n =416)	Unadjusted OR (95% Confidence Interval)	Absolute Risk Reduction (% Reduction in Risk)	Number Needed to Treat^*
LBW	10.9% (n=44)	12.8% (n=53)	0.84 (0.55 – 1.29)	1.9% (15%)	53
VLBW	1.0% (n=4)	2.2% (n=9)	0.45 (0.14 – 1.48)	1.2% (55%)	83
PTB	11.9% (n=48)	13.0% (n=54)	0.91 (0.60 – 1.38)	1.1% (8%)	91
VPTB	2.2% (n=9)	5.0% (n=21)	0.43 (0.20 – 0.95)	2.8% (56%)	36

LBW: low birth weight, VLBW: very low birth weight, PTB: preterm births, VPTB: very preterm birth, OR: Odds Ratio.

Both odds ratio and number needed to treat are measures of the effect size to assess clinical significance.