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pubmed:otherAbstract |
PIP: Birthweight, birth order, and parental age were abstracted from 1,515,443 New York State birth certificates to study the association between the birth of an infant weighing less than 2501 g and parental age. The percentage of premature infants was greatest for birth order 1 and 6+ and showed a minimum at birth order 3. When maternal age and birth order were analyzed jointly, a strong interaction was found. Young mothers showed a tendency to have an increasing proportion of low birthweight infants with increasing birth order, whereas, the exact opposite was true for mothers older than 45. The intermediate maternal age categories reflected this change from an association of increasing proportion of low birthweight infants with increasing birth order to a pattern of decreasing proportion of premature imfants with increasing birth order. In data stratified to eliminate the influence of maternal age and to some extent birth order, paternal age was shown to affect the percentage of infants weighing less than 2501 g. This association was described by a flat n-shaped curve that was significantly different from a horizontal line (P.01) in 6 of 7 maternal age categories.
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