at the same time the share of mothers under the age of has declined from per cent to only per cent this small share of very young mothers combined with the reduced sample size in the 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