Telomeres are an essential part of human cells that affect how cells age. Just as the plastic tips at the end of shoelaces prevent the laces fraying so that they can continue to do their job effectively, telomeres are the caps at the end of each strand of DNA that prevent DNA strands becoming damaged.

Cells replenish by copying themselves, and this process continuously occurs throughout a lifetime. Every time a cell copies itself, while the DNA remains intact, telomeres become shorter. Longer telomeres allow cells to divide more often. Ultimately, over a lifetime, telomeres become too short to work, which causes cells to age and stop functioning properly.

Telomeres shorten with age. However, telomeres can also become shortened through stress, smoking, lack of exercise, and poor diet. Telomere shortening is involved in all aspects of the aging process on a cellular level; short telomeres are linked to premature cellular aging. Telomere length represents an individual's biological age as opposed to chronological age.

A relationship has previously been found between telomere length in adults and age-related diseases, such as cardiovascular disease, type 2 diabetes, and increased mortality. Now, in a new study - published in BMC Medicine - researchers have conducted telomere research in newborns.
Assessing how maternal BMI affects telomere length

The team hypothesized that overweight or obesity during pregnancy could be a major factor in the telomere length of the child at birth and may, as a result, contribute to the developmental programming of the child.

The aim of the study was to evaluate the possible effects of maternal obesity in newborns on telomere length measured in the newborn's cord blood DNA and placental DNA.

"Compared with newborns of mothers with a normal BMI [body mass index], newborns of women with obesity are older on a molecular level, because shortened telomere lengths mean that their cells have shorter lifespans," says Prof. Tim Nawrot, the corresponding author. "So maintaining a healthy BMI during a woman's reproductive age may promote molecular longevity in the offspring."

Telomere lengths were measured in 743 samples of cord blood and 702 samples of placental tissue from newborns of mothers involved in the ENVIRONAGE birth cohort study in Belgium. The 743 women included in the research were between the ages of 17-44, and the average pre-pregnancy BMI was 24.1.
Each one-point rise in maternal BMI shortens offspring's life by 1-2 years

Previous research has indicated that people usually lose around 32.2-45.5 telomere base pairs per year during adulthood. This study showed that for every one-point increase in the mothers' BMI, telomeres in the newborns were around 50 base pairs shorter.

The 50 base pair shortening of telomere length in newborns is equivalent to the length people typically lose in 1.1-1.6 years of adult life, which may put children with shorter telomeres at a greater risk of chronic diseases in adulthood, such as heart disease and type 2 diabetes.

Co-author Dries Martens notes that the team ruled out various other factors that may potentially be associated with telomere length, including parents' age, socioeconomic class, ethnicity, mothers' smoking status, newborns' gender, and birth weight.

"Prior to our study, there was no evidence of an association between pre-pregnancy BMI and newborn telomere length, although meta-analyses suggest an association between BMI and telomere length in adults," says Prof. Nawrot.

    "Our results add to the growing body of evidence that high maternal BMI impacts fetal programming, which could lead to altered fetal development and later life diseases. The public health impact of our findings is considerable as in affluent societies about 30 percent of women of reproductive age are overweight."  Prof. Tim Nawrot

Limitations of the study may include lack of data on paternal BMI. Previous studies have reported heritable changes in gene expression linked to the weight of a father on their newborn