Maternal cotyledons at birth predict blood pressure in childhood

Introduction: A small placental surface at birth has been shown to be associated with the development of hypertension in later life. In this study we extend this observation by looking at the relationship between the number of placental cotyledons and blood pressure in childhood. Because the number of cotyledons is correlated with the surface area, we hypothesized that fewer cotyledons would be associated with higher blood pressure. Methods: The Alspac study is a longitudinal study of 13,971 children born in Bristol. Their placentas were stored in formalin.We photographed the placentas of a sample of the children and related the number of maternal cotyledons to their blood pressure levels at age 9 years. Results: Contrary to our hypothesis, a greater number of maternal cotyledons was associated with higher blood pressure. Among boys, a greater number of cotyledons was associated with higher systolic and diastolic pressure but not with higher pulse pressure. Diastolic pressure rose by 2.2 mmHg (95% CI 0.6 to 3.7, p = 0.007) for every 10 additional cotyledons. Among girls, a greater number of cotyledons was associated with higher systolic pressure and pulse pressure but not with higher diastolic pressure. Pulse pressure rose by 2.7 mmHg (1.1e4.3, p < 0.001) for every 10 additional cotyledons. These associations were little changed by adjustment for placental surface area. Conclusion: Our study has shown that a large number of maternal cotyledons is associated with raised blood pressure in childhood. The associations differ in the two sexes.