Intra-uterine growth restriction and increased risk of hypertension in adult life: A follow-up study of 50-year-olds

Summary

Objective

To compare blood pressure between 50-year-old adults who were born at term (37–42 weeks of gestation) with intra-uterine growth restriction (IUGR; birth weight <10th centile) and a control group of similar age born at term without IUGR (birth weight ≥10th centile).

Study design

Controlled comparative study.

Methods

Participants included 232 men and women who were born at the Royal Maternity Hospital, Belfast, a large regional maternity hospital in Northern Ireland, between 1954 and 1956. One hundred and eight subjects who were born with IUGR were compared with 124 controls with normal birth weight for gestation. The main outcome measures were systolic and diastolic blood pressure at approximately 50 years of age, measured according to European recommendations.

Results

The IUGR group had higher systolic and diastolic blood pressure than the control group: 131.5 [95% confidence interval (CI) 127.9–135.1] vs 127.1 (95% CI 124.3–129.2) mmHg and 82.3 (95% CI 79.6–85.0) vs 79.0 (95% CI 77.0–81.0) mmHg, respectively. After adjustment for gender, the differences between the groups were statistically significant: systolic blood pressure 4.5 (95% CI 0.3–8.7) mmHg and diastolic blood pressure 3.4 (95% CI 0.2–6.5) mmHg (both P < 0.05). More participants in the IUGR group were receiving treatment for high blood pressure compared with the control group [16 (15%) vs 11 (9%)], although this was not statistically significant. The proportion of subjects with blood pressure >140/90 mmHg or currently receiving antihypertensive treatment was 45% (n = 49) for the IUGR group, and 31% (n = 38) for the control group (odds ratio 1.9, 95% CI 1.1–3.3). Adjustment for potential confounders made little difference.

Conclusions

IUGR is associated with higher blood pressure at 50 years of age. Individuals born with IUGR should have regular blood pressure screening and early treatment as required. Hypertension remains underdiagnosed and undertreated in adult life.

Introduction

Hypertension is a major public health concern and is among the classic cardiovascular risk factors,¹ estimated to affect one in three of the population.² It remains the most common treatable risk factor for cardiovascular disease in people >50 years of age, but studies show that it is still underdiagnosed, undertreated and poorly controlled.3, 4

The inverse relationship between birth weight and blood pressure in adult life has provided some of the strongest and most consistent support for the fetal origins hypothesis of adult disease.⁵ A systematic review based on 34 studies of more than 66,000 people of all ages in many countries concluded that blood pressure in adults is inversely related to birth weight.⁶ Birth weight or low birth weight, rather than weight for gestational age, has been the main focus of attention.

Recent obstetric practice has improved techniques for detecting intra-uterine growth restriction (IUGR) which remains a significant cause of fetal morbidity and mortality,⁷ with effects extending beyond the immediate perinatal period. A recent study has shown that some catch-up growth following birth can be achieved,⁸ but the long-term implications of being born small for gestational age are still unclear. The aim of this study was to determine if being born small for gestational age, rather than with low birth weight, is a significant risk factor for long-term morbidity in adult life.