Early developmental outcomes predicted by gestational age from 35 to 41 weeks
Section snippets
Methods
This study is a retrospective analysis of infant developmental screening results collected by the Family Futures' Connections program, a non-profit, child development support program in Michigan. Family Futures uses county birth records to contact the families of all infants born in three Michigan counties and offers free enrollment in the Connections program that provides age appropriate developmental screening tools, the Ages and Stages Questionnaire (ASQ [18], [19]), across the first five
Statistical analyses.
The unique relationship between GA and risk for developmental delay was modeled in two ways. Gestational age was tested as a predictor of overall amount of risk for any developmental delay and as a predictor of risk for developmental delay in specific developmental domains.
GA as a predictor of overall risk for any developmental delay at each time-point
Mean GA, mean overall risk score and proportion of children with a low score in at least one ASQ domain can be found for each sample in Table 1. Gestational age at birth was a significant predictor of overall risk for developmental delay after controlling for the set of demographic covariates in the 8-month sample, t(1) = − 2.49, p < 0.013; the 12-month sample, t(1) = − 2.17, p < 0.031; the 20-month sample, t(1) = − 5.13, p < 0.001; and the 24-month sample, t(1) = − 3.97, p < 0.001. In other words, in every
Discussion
Our results indicated that shorter gestation is associated with greater risk for developmental delays in the first two years among children who were born between 35 and 41 weeks of gestation. The “dose-response effect” of GA on development found in our study is consistent with results of other studies using the ASQ [25], [26], [27] and studies using other standard measures to assess developmental outcomes [4], [11], [28]. The graded influence of GA was seen across all four time-points in the
Limitations
Limitations of this study included that GA was parent reported and that we had no information about why an infant was born early. Perhaps most significantly, our measure of development, the ASQ, is meant as a screening tool, not a diagnostic tool. A low score in an ASQ domain can be interpreted as a delay relative to other infants of the same age, but is not the same as a diagnosis of a specific developmental delay. We also did not have enough data for infants born at 34 and 42 weeks of
Conclusions and implications
Our results clearly demonstrated the “dose-response effect” of prematurity [7], [11] because we were able to treat GA as a continuous variable. With each additional week of gestation toward 41 weeks, the overall risk for developmental delay gradually decreased. Our results also pointed out that some developmental domains were especially sensitive to the negative effects of early birth. In practice, our study may be used to caution against elective early births [34], [35], and to demand that
Acknowledgements
We would like to thank the staff and volunteers at Family Futures for their dedication to improving outcomes for all children as well as the families who participated in the Family Futures’ Connections program.
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