Pregnancy and breastfeeding are linked to stronger cognition in postmenopausal women, a long-term study suggests.

Greater cumulative time spent pregnant and time spent breastfeeding correlated with higher overall scores in the study, including verbal and visual memory, in later life.

Researchers analysed annual assessments of more than 7,000 women aged about 70 for up to 13 years using data from the Women’s Health Initiative Memory Study and the Women’s Health Initiative Study of Cognitive Aging.

On average, those who were pregnant for around 30.5 months were expected to have a 0.31 per cent higher global cognition score than those who had never been pregnant.

A lifetime average of 11.6 months of breastfeeding was linked to a 0.12 per cent higher global score.

Each additional month spent pregnant was associated with a 0.01-point rise in overall ability.

Each extra month of breastfeeding showed the same increase, and a 0.02-point gain in verbal and visual memory. Although small, these effects are similar to known protective factors such as not smoking and high physical activity.

The work was led by Molly Fox, an anthropology professor at the University of California, Los Angeles.

Fox said: “Any ways in which we can focus public health outreach or clinical interventions towards higher-risk populations leads to more effective and efficient efforts.”

Participants who had ever been pregnant scored, on average, 0.60 points higher than those who had never been pregnant.

Those who had breastfed scored 0.19 points higher overall and 0.27 points higher for verbal memory than those who had never breastfed.

Women are disproportionately affected by Alzheimer’s disease, a progressive condition that impairs memory and thinking skills, and this is not fully explained by life expectancy differences.

The authors say biology and social factors may both play roles.

They noted that more adult children could contribute to cognitive health by buffering stress, supporting wellbeing or encouraging healthy behaviour.

“If we can figure out, as a next step, why those reproductive patterns lead to better cognitive outcomes in old age, then we can work towards figuring out how to craft therapies, for example, new drugs, repurposed drugs or social programmes, that mimic the naturally occurring effect we observed,” said Fox.

The study team is now working to identify the mechanisms that link reproductive histories to cognitive resilience.

Scientists say they have ‘rejuvenated’ human eggs, in work that could improve IVF success rates for older women.

The team reports that an age-related defect causing genetic errors in embryos may be reversed by supplementing eggs with a key protein.

In eggs donated by fertility patients, microinjection of the protein cut the share showing the defect from 53 per cent to 29 per cent.

The findings were presented at the British Fertility Conference in Edinburgh by researchers from the Max Planck Institute for Multidisciplinary Sciences in Göttingen.

The technique is being commercialised by Ovo Labs, co-founded by professor Melina Schuh, who led the research.

The approach targets problems in meiosis, the process where eggs halve their genetic material before fertilisation.

In older eggs, chromosome pairs can loosen and separate too soon, leading to embryos with too many or too few chromosomes, known as aneuploidy.

The researchers found levels of a protein called Shugoshin 1, which helps hold chromosome pairs together, decline with age. Microinjections appeared to restore this “molecular glue” and reduce errors.

Professor Schuh said: “Overall we can nearly halve the number of eggs with [abnormal] chromosomes. That’s a very prominent improvement.

“Most women in their early 40s do have eggs, but nearly all of the eggs have incorrect chromosome numbers. This was the motivation for wanting to address this problem.

“What is really beautiful is that we identified a single protein that, with age, goes down, returned it to young levels and it has a big effect.

We are just restoring the younger situation again with this approach.

Declining egg quality is a major reason IVF success rates fall steeply with age.

UK figures show an average birth rate of 35 per cent per embryo transferred for patients under 35, dropping to 5 per cent for women aged 43 to 44.

Dr Agata Zielinska, co-founder and co-chief executive of Ovo Labs, said: “Currently, when it comes to female factor infertility, the only solution that’s available to most patients is trying IVF multiple times so that, cumulatively, your likelihood of success increases.

“What we envision is that many more women would be able to conceive within a single IVF cycle.”

The approach would not extend fertility beyond menopause.

The team is in talks with regulators about a clinical trial.

Dr Güneş Taylor, of the University of Edinburgh, who was not involved, said: “This is really important work because we need approaches that work for older eggs because that’s the point at which most women appear.

“If there’s a one-shot injection that substantially increases the number of eggs with properly organised chromosomes, that gives you a better starting point.”