Male babies born to older mothers have a higher risk of heart problems because the placenta doesn't work as well, according to a study on rats.
The study was conducted by the University of Cambridge and published in the journal Scientific Reports. It found that changes in the placentas of older mothers could damage the health of male babies, according to Science Daily. Older mothers in the research were the rat equivalent of a pregnant woman aged 35 or older, which is considered a geriatric pregnancy. Rats are used since their biology is similar to humans'.
The research showed that male babies suffered negative consequences of the late birth, while females did not. In fact, in certain cases, the females even appeared to benefit. The researchers said placentas became less efficient at transporting nutrients and oxygen to foetuses as the mothers got older.
"With the average age of first pregnancy in women becoming higher and higher, it is very important to understand how the age of the mother and the sex of the baby interact to determine pregnancy and later-life health of the child," said Dr. Amanda Sferruzzi-Perri.
According to the researchers, the placenta, which connects mother to baby in the womb, is 'highly dynamic'. They added that genetic changes in a woman as she ages could affect how the placenta functions. It was also found that babies of either sex did not grow as large in the placentas of older women. And the males were more likely to have high blood pressure or heart problems as they grew older because the mother's had a different internal shape and became less efficient. However, female babies did not suffer the same risk.
The scientists revealed that, in the combination of older mother and female baby, the placenta actually "showed beneficial changes in structure and function that would maximise the support of fetal growth". Similar discoveries about males have been made before but it was not well understood why they were at a particular disadvantage. The new research shows the genes involved in the older mother-male baby mix make the placenta less able to do its job.
According to Cambridge's Dr. Tina Napso: "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. 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."