Background: Individuals who are small at birth are at increased risk of ischaemic heart disease (IHD) in later life. One hypothesis to explain this association is fetal adaptation to a suboptimum intrauterine environment. We investigated whether pregnancy complications associated with low birthweight are related to risk of subsequent IHD in the mother.
Methods: Routine discharge data were used to identify all singleton first births in Scotland between 1981 and 1985. Linkage to the mothers' subsequent admissions and deaths provided 15--19 years of follow-up. The mothers' risks of death from any cause or from IHD and admission for or death from IHD were related to adverse obstetric outcomes in the first pregnancy. Hazard ratios were adjusted for socioeconomic deprivation, maternal height and age, and essential hypertension.
Findings: Complete data were available on 129,920 (95.6%) eligible deliveries. Maternal risk of IHD admission or death was associated with delivering a baby in the lowest birthweight quintile for gestational age (adjusted hazard ratio 1.9 [95% CI 1.5--2.4]), preterm delivery (1.8 [1.3--2.5]), and pre-eclampsia (2.0 [1.5--2.5]). The associations were additive; women with all three characteristics had a risk of IHD admission or death seven times (95% CI 3.3--14.5) greater than the reference category.
Interpretation: Complications of pregnancy linked to low birthweight are associated with an increased risk of subsequent IHD in the mother. Common genetic risk factors might explain the link between birthweight and risk of IHD in both the individual and the mother.