Table 7.

Interaction between groups that received preconception or pregnancy interventions compared with those that did not receive these interventions

Primary outcome	No preconception intervention			Preconception intervention		Measure of interaction (95% CI)
	% or mean (SD)	IRR or MD (95% CI)		% or mean (SD)	IRR or MD (95% CI)
Low birth weight
No pregnancy intervention	28.6	1.00		21.9	0.78 (0.67 to 0.91); P=0.001	1.20 (0.97 to 1.48); P=0.10
Pregnancy intervention	24.6	0.82 (0.69 to 0.96); P=0.01		23.4	0.76 (0.65 to 0.88); P<0.001
Preterm birth
No pregnancy intervention	14.8	1.00		12.6	0.88 (0.71 to 1.09); P=0.24	1.52 (1.11 to 2.08); P=0.01
Pregnancy intervention	10.2	0.69 (0.54 to 0.89); P=0.005		13.3	0.91 (0.73 to 1.14); P=0.41
Small for gestational age
No pregnancy intervention	37.2	1.00		29.9	0.81 (0.72 to 0.91); P=0.001	1.17 (0.98 to 1.40); P=0.09
Pregnancy intervention	28.7	0.76 (0.66 to 0.87); P<0.001		27.9	0.71 (0.62 to 0.81); P<0.001
Birth weight (g)
No pregnancy intervention	2744 (459)	0.00		2816 (449)	65 (26 to 103); P=0.001	−47 (−101 to −7); P=0.09
Pregnancy intervention	2785 (439)	60 (17 to 103); P=0.007		2797 (438)	77 (36 to 119); P<0.001
Birth length (cm)
No pregnancy intervention	47.9 (2.2)	0.00		48.19 (2.07)	0.29 (0.11 to 0.47); P=0.002	−0.23 (−0.48 to 0.02); P=0.08
Pregnancy intervention	48.0 (2.1)	0.21 (−0.01 to 0.41); P=0.05		47.98 (2.06)	0.23 (0.02 to 0.44); P=0.03
Length-for-age z score at 24 months
No pregnancy intervention	−1.0 (1.2)	0.00		−1.00 (1.13)	0.01 (−0.15 to 0.17); P=0.90	0.12 (−0.10 to 0.34); P=0.28
Pregnancy intervention	−0.7 (1.1)	0.31 (0.14 to 0.48); P<0.001		−0.58 (1.17)	0.46 (0.30 to 0.63); P<0.001
Stunting at 24 months
No pregnancy intervention	18.8	1.00		19.4	0.98 (0.73 to 1.32); P=0.91	0.92 (0.56 to 1.54); P=0.76
Pregnancy intervention	10.9	0.56 (0.37 to 0.84); P=0.005		10.4	0.49 (0.34 to 0.70); P<0.001

CI=confidence interval; IRR=incidence rate ratio; MD=mean difference; SD=standard deviation.