At the same time, the share of mothers under the age of 20 has declined from 10.8 per cent to only 6.1 per cent. This small share of very young mothers, combined with the reduced sample size in the 10-year period before the survey, results in a larger standard error in estimation (II), rendering the estimated coefficient for the effect of being born to a younger mother statistically insignificant. In view of this trend, we also conclude that the change in the behavioural patterns away from very young motherhood is likely to have contributed to the observed decrease in Jordan’s infant and child mortality. As the sample size decreases drastically for estimation (III), the smoking variable maintains its sign but loses significance (owing to large standard errors).