Background: The link between maternal factors and birth outco mes is well established. Substantial changes in society and medical care over time have influenced women's reproducti ve choices and health, subsequently affecting birth outcomes. The objective of this study was to describe tempor al changes in key maternal and fetal factors affecting birth outcomes in Newc astle upon Tyne over three decades, 1961–1992. Methods: For these descriptive analyses we used data from a populatio n-based birth record database constructed for the historical cohort Pa rticulate M atter and P erinatal E vents R esearch (PAMPER) study. The PAMPER database was created using details from paper-base d hospital delivery and neon atal records for all births during 1961–1992 to mothers resident in Newcastle (out of a total of 109,086 sing leton births, 97,809 hospital births with relevant information). In addition to hospital records, we used other sources for data collection on births not included in the delivery and neonatal records, for death and stillbirth registrations and for validation. Results: The average family size decreased ma inly due to a decline in the propor tion of families with 3 or more children. The distribution of mean maternal ages in al l and in primiparous women was lowest in the mid 1970s, corresponding to a peak in the propor tion of teenage mothers. The propor tion of older mothers declined until the late 1970s (from 16.5% to 3.4%) fo llowed by a steady incr ease. Mean birthweight in all and term babies gradually increased from the mid 1970s. The increase in the percentage of preterm birth paralleled a two-fold increase in the percentage of caesarean section amon g preterm births during the last two decades. The gap between the most affluent and the most deprived gro ups of the population widened over the three decades. Conclusion: Key maternal and fetal factors affecting birth outco mes, such as maternal age, parity, socioeconomic status, birthweight and gestational age, changed substa ntially during the 32-year period, from 1961 to 1992. The availability of accurate gestat ional age is extremely important for correct interpretation of trends in birthweight.