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,p¼0.007) 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