High blood pressure during pregnancy can affect a child's thinking skills throughout its life, research suggests.
Scientists studied 398 men born between 1934 and 1944 whose mothers' blood pressure during pregnancy was recorded in their medical records.
The men were tested for language skills, maths reasoning and visual and spatial ability at the age of 20 and again at an average age of 69.
Men whose mothers experienced high blood pressure while pregnant performed less well than those whose mothers never suffered the problem. On average, they scored 4.36 points lower on the tests at 69 years old.
The same group also had lower scores at the age of 20, and their scores declined faster over the decades than did those of the other men. The biggest impact was on maths-related reasoning.
Lead scientist Dr Katri Raikonen, from the University of Helsinki in Finland, said: "High blood pressure and related conditions such as pre-eclampsia complicate about 10% of all pregnancies and can affect a baby's environment in the womb.
"Our study suggests that even declines in thinking abilities in old age could have originated during the prenatal period when the majority of the development of brain structure and function occurs."
The findings are published in the latest online issue of the journal Neurology.