Neonatal Death and Best Gestational Age for Delivery at Term
Neonatal Death and Best Gestational Age for Delivery at Term
The challenge for obstetricians has always involved decisions that balance competing risks and benefits for fetuses, infants and mothers. Factors affecting the timing of delivery involve at least three heterogeneous sets of risks and two individuals. As recently noted regarding fetal death and maternal age, decisions regarding obstetric management are complex and include consideration of maternal condition, risk of fetal death, obstetric conditions, the result of (or the need for) fetal surveillance, as well as neonatal outcomes.
The current recommendation to avoid delivery before 39 weeks addresses only one aspect of this complex decision based primarily on minimizing neonatal morbidity and mortality seen with earlier delivery (a declining risk over time). This uniform recommendation does not allow for natural variation in gestational age-related postdelivery risk, nor does it address the observed increasing risk of fetal death associated with gestational ages beyond 37 weeks or the incremental morbidity and mortality risks to mothers associated with continued pregnancy.
Methodological limitations associated with the current 39-week recommendation include the conflation of observed rates of outcomes with statements of prospective risk assessment. Aggregated observational data should not be assumed to be an adequate proxy for individual or subgroup-specific risk when heterogeneous factors and conditions contribute to fetal, infant and maternal morbidity and mortality. The observational data used to help inform decisions about deliveries are clearly confounded by susceptibility, selection and attrition. In addition, raw data used to calculate the rates of outcomes include pregnancies for which early-term nonindicated delivery (the intervention of interest) will not alter fetal or infant death rates. Such cases should be excluded. Widespread implementation of the 39-week recommendation may improve some outcomes, but may also impose unintended consequences on others.
An aggressive research agenda needs to be developed to address these important concerns and limitations. Treatment options that consider acceptable trade-offs among the often competing risks and benefits for fetuses, infants and mothers will require data on key risk subgroups, approaches that consider the interests of both individuals involved and that yield recommendations that are based on research results that are reproducible and valid. However, although further analysis and data will help better inform decision-making, it is unlikely, in our opinion, that any one-size-fits-all recommendation will be best. Individualized determinations regarding the timing of delivery at term based on patient-specific factors will be the likely preferred approach. It is essential that this discussion begin.
Conclusion
The challenge for obstetricians has always involved decisions that balance competing risks and benefits for fetuses, infants and mothers. Factors affecting the timing of delivery involve at least three heterogeneous sets of risks and two individuals. As recently noted regarding fetal death and maternal age, decisions regarding obstetric management are complex and include consideration of maternal condition, risk of fetal death, obstetric conditions, the result of (or the need for) fetal surveillance, as well as neonatal outcomes.
The current recommendation to avoid delivery before 39 weeks addresses only one aspect of this complex decision based primarily on minimizing neonatal morbidity and mortality seen with earlier delivery (a declining risk over time). This uniform recommendation does not allow for natural variation in gestational age-related postdelivery risk, nor does it address the observed increasing risk of fetal death associated with gestational ages beyond 37 weeks or the incremental morbidity and mortality risks to mothers associated with continued pregnancy.
Methodological limitations associated with the current 39-week recommendation include the conflation of observed rates of outcomes with statements of prospective risk assessment. Aggregated observational data should not be assumed to be an adequate proxy for individual or subgroup-specific risk when heterogeneous factors and conditions contribute to fetal, infant and maternal morbidity and mortality. The observational data used to help inform decisions about deliveries are clearly confounded by susceptibility, selection and attrition. In addition, raw data used to calculate the rates of outcomes include pregnancies for which early-term nonindicated delivery (the intervention of interest) will not alter fetal or infant death rates. Such cases should be excluded. Widespread implementation of the 39-week recommendation may improve some outcomes, but may also impose unintended consequences on others.
An aggressive research agenda needs to be developed to address these important concerns and limitations. Treatment options that consider acceptable trade-offs among the often competing risks and benefits for fetuses, infants and mothers will require data on key risk subgroups, approaches that consider the interests of both individuals involved and that yield recommendations that are based on research results that are reproducible and valid. However, although further analysis and data will help better inform decision-making, it is unlikely, in our opinion, that any one-size-fits-all recommendation will be best. Individualized determinations regarding the timing of delivery at term based on patient-specific factors will be the likely preferred approach. It is essential that this discussion begin.
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