Children may benefit from having older mothers

By Piriya Mahendra, medwireNews Reporter

The children of older mothers may have improved health and development up to 5 years of age, say researchers in the British Medical Journal.

The results of this study conflict with concerns that have been raised about older people who use fertility treatment and the possible risks to children delivered by older mothers, comment Edward Melhuish (University of London, UK) and team.

They found that the risk for children having both unintentional injuries requiring medical attention or being admitted to hospital declined with increasing maternal age. Indeed, the risk for 3-year-olds experiencing unintentional injuries was 27.1% if their mothers were 20 years old versus 21.6% if their mothers were aged 40 years.

Hospital admissions for 3-year-olds with 20-year-old mothers were also higher than those who had 40-year-old mothers, at 27.1% versus 21.6%.

In addition, immunization rates in 9-month-olds were lower in those who had 20-year-old mothers, at 94.6% versus those with mothers aged 40-years-old, at 98.1%. Immunization rates were highest (81.3%) in 9-month-olds whose mothers were aged 27 years old and lower for children of younger or older mothers.

A model of immunizations excluding measles, mumps, and rubella immunization revealed that there was no significant association between immunization rate and maternal age, "indicating that nonlinear effects are linked to take-up of the combined measles, mumps, and rubella immunization," write the authors.

Children with older mothers also benefitted in terms of language development. Indeed, 3-year-old children with 40-year-old mothers scored 0.22 standard deviations (SDs) higher on the British ability scales of naming vocabulary than children of mothers aged 20 years.

Children of 20-year-old mothers had more social and emotional difficulties than those of 40-year-old mothers, scoring 0.28 SDs lower on a quadratic model for the strengths and difficulties total problem score in relation to maternal age.

"The findings are noteworthy given the continuing increase in mean age of childbearing," say Melhuish et al.

They add that possible mechanisms for the observed relations between child outcome and maternal age could be environmental, such as differences in parenting, or genetic, as it is for paternal age according to previous studies.

Such studies have shown that the longer fathers wait to have children, the more likely their children are to live long and healthy lives. This apparently was due to the longer telomeres of older fathers' sperm, which was related to increased longevity and development.

The authors conclude: "Further research should explore possible mechanisms."

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