Placenta changes in older mothers may be linked to a higher risk of heart problems in their male offspring, according to a study in rats. The researchers, including those from the University of Cambridge in the UK, analysed the placenta of young (3-4 months old) and aged rats (9.5-10 months old) that were pregnant with male and female offspring.
They said the placenta -- an organ attached to the walls of the uterus, and connecting to the umbilical cord of the growing fetus -- transported nutrients and oxygen from the mother to the growing offspring, helping her support fetal development. The organ is the main protective barrier for the fetus against toxins, bacteria, and hormones - such as stress hormones - in the mother's blood, they added.
The study, published in the journal Scientific Reports, noted that advanced maternal age reduced the efficiency of the placenta of both male and female fetuses. "Advanced maternal age alters placental phenotype in a sex-specific fashion. These sexually-divergent changes may play a role in determining health outcomes of female and male offspring of aged mothers," the researchers wrote in the study.
The researchers said ageing in mothers affected the structure and function of the placenta more markedly for male fetuses, reducing the organ's ability to support their growth. These changes potentially increased the likelihood of later-life heart problems and high blood pressure in the male offspring, they said.
"A pregnancy at an older age is a costly proposition for the mother, whose body has to decide how nutrients are shared with the fetus. That's why, overall, fetuses do not grow sufficiently during pregnancy when the mother is older compared to when she is young," said study co-author Tina Napso from the University of Cambridge.
"We now know that growth, as well as gene expression in the placenta is affected in older mothers in a manner that partially depends on sex: changes in the placentas of male fetuses are generally detrimental," Napso said.
The researchers, however, cautioned that more studies are needed to see if the findings apply to humans. The researchers plan to build on these results, and find ways of improving the function of the placenta to optimise growth of the fetus.