Child and maternal mortality and morbidity are examined in relation to the interval between pregnancies. Most data available pertain to child mortality. Very little reliable information links child morbidity or maternal health detriments to short birth spacing. The evidence on child mortality suggests that very short intervals (conceptions less than six months after a birth) are detrimental to survival of the second child, but these results must be viewed in light of the methodological difficulties of studies of this subject. Policy implications of the data are perhaps less clear than is sometimes assumed.