Having last baby after 35 makes women sharper in old age

Women have better brainpower after menopause if they had their last baby after age 35, says a study.

"Based on the findings, we would certainly not recommend that women wait until they're 35 to close their family, but the study provides strong evidence that there is a positive association between later age at last pregnancy and late-life cognition," said lead author Roksana Karim, Assistant Professor at Keck School of Medicine of the University of Southern California in the US.

This is the first study to investigate the association between age at last pregnancy, which can be a marker of a later surge of pregnancy-related hormones, and cognitive function in later life, Karim added.

The main hormones at play are estrogen and progesterone. In animal studies, estrogen has a beneficial impact on brain chemistry, function and structure; progesterone is linked with growth and development of brain tissue, Karim said.

An outpouring of estrogen and progesterone, especially in later life, appears to be beneficial, Karim noted.

The study, published in the Journal of the American Geriatrics Society, included 830 women who, on average, were 60 years old. 

Participants were given a series of tests that included assessments of verbal memory, psychomotor speed, attention and concentration, planning, visual perception, and memory.

The researches found that postmenopausal women who had their last pregnancy after 35 had better verbal memory -- remembering a list of words or retelling a story after some distraction.

The study found that other reproductive events were also important to later life cognition. More time between first and last period -- longer reproductive life -- proved valuable for executive function.

"Starting your period early means you have higher levels of the female sex hormone being produced by the ovaries," Karim said. 

"Girls are receiving the optimal levels early, so it's possible that their brain structures are better developed compared to those who are exposed to estrogen levels associated with menstrual cycles at a later age," Karim noted.