Secular changes in early neonatal mortality in Norway, 1967-1981

Area of Science:

• Perinatal epidemiology
• Public health research
• Biostatistics

Background:

• Early neonatal mortality rates (ENMR) represent a key indicator of perinatal health.
• Understanding trends and contributing factors to ENMR is crucial for public health interventions.
• Previous analyses have not fully accounted for the interplay of multiple risk factors over time.

Purpose of the Study:

• To analyze secular trends in early neonatal mortality rates in Norway.
• To quantify the contributions of changes in risk factor distributions versus improved survival.
• To investigate mortality trends in specific subgroups, including infants of mothers with diabetes.

Main Methods:

• Utilized two five-year cohorts (1967-1971 and 1977-1981) from the Medical Birth Registry of Norway.
• Employed multivariate analysis to control for birth weight, parity, maternal age, and infant sex.
• Conducted separate analyses for women with specific conditions like diabetes.

Main Results:

• Crude ENMR decreased from 6.5 to 2.9 per 1,000 live births.
• 81.6% of the mortality improvement was attributed to enhanced survival within subgroups, while 18.4% was due to shifts in risk factor distributions.
• ENMR declined across all subgroups, with a more pronounced decrease observed in low birth weight infants.
• Infants of mothers with diabetes had a significantly higher odds ratio for mortality, and improved survival in this group contributed 2.9% to the overall ENMR reduction.

Conclusions:

• Significant improvements in early neonatal survival have been achieved, largely driven by medical advancements and better care within specific risk groups.
• Low birth weight infants and infants of mothers with diabetes represent critical subgroups where targeted interventions can yield substantial gains.
• Continued monitoring and research into factors influencing neonatal mortality are essential for further public health advancements.