Placenta changes could mean male offspring of older mums more likely to develop heart problems in later life.
Changes occur in the placenta in older pregnant mothers leading to a greater likelihood of poor health in their male offspring, a study in rats has shown. Both male and female foetuses do not grow as large in older mothers, but there are sex-specific differences in changes to placental development and function. These are likely to play a central role in the increased likelihood of later-life heart problems and high blood pressure in males.
In humans, women over 35 are considered to be of advanced maternal age. The study, published in Scientific Reports, looked at pregnant rats of a comparable age. In aged mothers, the placenta of female foetuses showed beneficial changes in structure and function that would maximise the support of foetal growth. In some instances, the placenta even supported the female foetus better than the placenta of a younger mother. In the case of male foetuses however, the placenta showed changes that would limit foetal growth in the aged pregnant rats.
The placenta transports nutrients and oxygen from mother to foetus, secretes signalling factors into the mother so she supports foetal development, and is the main protective barrier for the foetus against toxins, bacteria, and hormones in the mother’s blood. It is highly dynamic in nature, and its function can change to help protect the growing foetus when conditions become less favourable for its development, for example through a lack of nutrients or oxygen or when the mother is stressed.
The study found that advanced maternal age reduced the efficiency of the placenta of both male and female foetuses. It affected the structure and function of the placenta more markedly for male foetuses, reducing its ability to support growth of the foetus.
A pregnancy at an older age is a costly proposition for the mother, whose body has to decide how nutrients are shared with the foetus. That’s why, overall, foetuses do not grow sufficiently during pregnancy when the mother is older compared to when she is young.