From Birth to Senescence. Studies on factors at birth and their relation to morbidity in women in adult life

Abstract: This thesis is concerned with factors at birth and their relation to disease in later adulthood. The aims of this thesis were to a) identify variables in Swedish midwife records at the early part of the 1900's and their relation to birth outcome; b) assess agreement between self-reported birth weight and recorded birth weight; and, c) examine the relationship between size at birth and 1) hypertension, and, 2) cancer morbidity in adult women. Original midwife records for five birth cohorts of women in Göteborg, Sweden born in the years 1908, 1914, 1918, 1922 and 1930, combined with detailed health examinations, utilisation of national registries and continuous follow-up throughout the life span, serve as the basis for analysis. Delivery site changed from a vast majority of home births in 1908 to a slight majority of hospital births by 1930. Babies born in hospital were consistently smaller in size during this time period. Studies of factors at birth in the early part of the 1900's should include both home and hospital births to avoid selection bias. Poor agreement was found between self-reported birth weights and those from original midwife records in women aged 44-60 years. Application of self-reported birth weight in analysis of cardiovascular risk factors led to false associations. Self-reported birth weights from middle-aged women are not an acceptable replacement for birth weights from original records. Hypertension risk was assessed in women at both 50 and 60 years of age. Low weight or length at birth was associated with a significantly increased risk for hypertension at age 60 years. This was independent of adult body size as body mass index. This study supports the hypothesis that poor fetal growth, as measured by low weight or length at birth, may contribute to the development of hypertension in later life and that this relationship became stronger with age. High weight or length at birth was associated with a significant increase in risk for cancer in adult women. Inclusion of factors suspected to influence cancer risk did not attenuate this relation. This study suggests that high weight or length at birth may contribute to the development of cancer in later life indicating that size at birth may require consideration in the pathogenesis of adult cancers. These studies contribute to a growing body of evidence that fetal growth may have an important role for health in later life.