Elsevier

The Lancet

Volume 357, Issue 9273, 23 June 2001, Pages 2002-2006
The Lancet

Articles
Pregnancy complications and maternal risk of ischaemic heart disease: a retrospective cohort study of 129 290 births

https://doi.org/10.1016/S0140-6736(00)05112-6Get rights and content

Summary

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.

Introduction

Previous studies have shown an association between an individual's birthweight and his or her subsequent risk of ischaemic heart disease (IHD), hypertension, and diabetes mellitus.1 Barker and colleagues have postulated that fetal adaptation to inadequate intrauterine nutrition, due to poor maternal diet or placental dysfunction, results in physiological programming of a “thrifty phenotype”, which increases the risk of hypertension and IHD in later life. Babies might be small either because they are born preterm or because their intrauterine growth is suboptimum. An alternative hypothesis is that common genetic factors predispose to intrauterine growth restriction, preterm birth, and IHD.2 If this hypothesis is true, mothers who have pregnancies complicated by intrauterine growth restriction or preterm delivery should themselves be at increased risk of developing IHD. This study aimed to assess whether complications of pregnancy linked with low birthweight are associated with the mother's subsequent risk of IHD.

Section snippets

Selection of study cohort

The Scottish Morbidity Record (SMR) system collects routine discharge data on all patients admitted to Scottish National Health Service acute (SMR1) and maternity (SMR2) hospitals. The Information and Statistics Division of the Common Services Agency links all SMR records for an individual patient to each other and to the General Registrar's Office death database. The SMR2 system collects information on clinical and demographic characteristics and outcomes. Data on maternal smoking status have

Results

Between 1981 and 1985, 137 094 singleton first pregnancies resulted in the birth of a live infant. Data on gestational age at birth or birthweight were missing in 1142 (0·8%) cases. Of the remaining 135 952infants, 135 891 weighed at least 500 g at birth and were born between 24 and 43 weeks of gestation. Complete data on maternal age at the baby's birth, maternal height, and the infant's sex were available for 129 920 (95·6%). The case-mix and crude outcomes of the study cohort are summarised

Discussion

The main finding of this study is that there are additive associations between birthweight for gestational age, preterm birth, and a diagnosis of pre-eclampsia in the first pregnancy and the mother's risk of fatal and non-fatal IHD in later life (Table 2, Table 3). These associations were independent of maternal height and age, socioeconomic deprivation, and essential hypertension during pregnancy.

One possible explanation for the association between low birthweight quintile and risk of IHD is a

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