Introduction Previous studies have demonstrated an overall association between preterm delivery and maternal risk of subsequent ischaemic heart disease (IHD). The underlying mechanism for this is unknown. Furthermore, it is not known whether the association is specific to either elective or spontaneous preterm delivery. Our study examined the associations by type of preterm delivery with a view to helping to elucidate the mechanism underlying the association between preterm delivery and maternal IHD risk.
Methods We linked three Scottish routine data sources. The Scottish Health Survey (lifestyle risk factors including blood samples), Scottish Morbidity Record (all acute hospital admissions and all pregnancies) and death certificate data. Univariate and multivariate Cox proportional hazards models were used to explore the associations between preterm delivery and subsequent IHD events and deaths. Univariate and multivariate linear regression analyses were used to study the associations between preterm delivery and subsequent C reactive protein (CRP) concentration.
Results The cohort comprised 750 350 women who delivered a live, singleton infant following their first pregnancy. We demonstrated independent associations between preterm delivery and death due to IHD (HR 2.26, 95% CI 1.88 to to 2.71) and total IHD events (HR 1.58, 95% CI 1.47 to to 1.71). The associations were significantly greater for elective than spontaneous preterm delivery (p=0.005). There was a trend whereby the association between preterm delivery and IHD increased with decreasing age at first IHD event. CRP concentration was available in 1124 women. There was a significant overall association between preterm delivery and CRP (β=0.053, p=0.046) but, on sub-group analysis, this was found to be specific to elective preterm delivery (β=0.077, p=0.004).
Conclusions Elective preterm delivery is usually undertaken because of growth restriction or pre-eclampsia, resulting from placental dysfunction. The association between elective preterm delivery and both IHD with CRP, and the trend over age, suggests that a genetic predisposition to a pro-inflammatory state may be a common mechanism predisposing to both placental dysfunction and IHD.
- preterm birth
- myocardial ischaemia
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