Table 3.

Multivariable logistic models showing effect of mother’s education, age of twins, and gender of twins on adjusted odds ratios of association between twin births and divorce, US Census data, 1980

Variable	Odds ratio of divorce [95% CI]	p-value
No. observations	841,442
Mother completed > 1y college
Yes	0.99 [0.94–1.04]	0.04
No	1.12 [1.04–1.20]
Age of twins at time of survey
< 8 years old	0.95 [0.84–1.07]	< 0.01
≥ 8 years old	1.15 [1.05–1.24]
Gender of twins
Two boys	0.96 [0.84–1.08]	0.02
At least one girl	1.15 [1.07–1.25]

Notes: Reported p-values reflect two-sided tests of equivalence of odds ratio of divorce associated with twin births when comparing groups (e.g. mothers completing at least one year of college to mothers not). All models adjusted for age of mother at first birth, age at marriage, and an indicator for being white.