Cardiovascular disease is the main cause of death worldwide. Although the onset of these diseases is often linked to lifestyle factors such as obesity, more evidence suggests that events occurring earlier in one’s life can be a factor.
In a recent article in BMC Medicine, a team led by researchers at Tokyo Medical and Dental University (TMDU) investigated how low birth weight and fetal growth restrictions could result from the mother’s genetic variants of hypertension-related genes. It is interesting to note that these effects may occur even if the mother is not having high blood pressure during the course of her pregnancy.
The mother’s genes can affect the child’s development by directly passing specific alleles down, but they can also affect the child indirectly through the intrauterine environment. Studies investigating these phenomena have recently revealed that women with genes that are associated with hypertension are more likely to give birth to children with low birth weight.
Researchers and clinicians assumed that mothers with high blood pressure will have babies who are heavier. However, no association was observed. The TMDU group concluded that the intrauterine environment played an important role in this instance. They believed that all of these findings were due to the effects on the placenta.
Because the placenta is an organ that is extremely vascular that is why we have concentrated our attention on it. The weight of the placenta is frequently correlated with the birth weight. Numerous blood pressure-related genes have been discovered in genome-wide association studies.
Noriko Sato, Study Lead and Associate Professor, Department of Molecular Epidemiology, Tokyo Medical and Dental University
Researchers looked at the fetal development of a group of Japanese people. They utilized the risk of genetics for developing hypertension over the course of their life, called a polygenic risk score to examine how maternal genetic risk score affected placental weight and birth weight. Then the mediating role of the placenta regarding influence on birth weight was confirmed using a method known as a causal mediation analysis.
“We also looked at the genetic variants of vascular-related blood pressure genes to see whether the impact on birth weight might be ultimately through placental growth,” says Naoyuki, Professor and Senior Author of Comprehensive Reproductive medicine. “Nearly 100% of the effect of “vasculature-related” genetic score on birth weight was indeed mediated by placental weight.”
The team also found an opposite relationship between maternal systolic blood pressure genetic risk score (maternal Systolic Blood Pressure) and the rate of fetal growth towards the endof the study, in particular at 36 weeks gestation.
Sato says, “Our findings suggest that the maternal-related genes that affect blood pressure are linked to the giddiness of the fetus that is undesirable, and the growth of the placenta.” “The intrauterine environment created by the vasculature in the placenta is the primarily relevant element here, rather than the mother’s blood pressure at the time of pregnancy.”
This study supports the notion that maternal genes that are associated with hypertension risk may in turn influence the development of a fetus and affect long-term child’s health via effects on their placenta. In more than a quarter of the pregnancies the restriction of fetal growth in late pregnancy is a frequent problem. It is hard to predict and difficult to identify.
However, incorporating maternal genetic risk information into clinical practice could enable screening and better perinatal care for the health of mother and child. Additionally, the results contribute to the discovery of new therapeutic targets for the treatment and prevention of cardiovascular diseases. These findings are fascinating because they can prevent disease from developing for decades before it’s possible.
Sato, N., and. (2021) Placenta mediates maternal hypertension polygenic score’s effect on offspring birth weight Study of a birth cohort with the fetal speed velocity. BMC Medicine. doi.org/10.1186/s12916-021-02131-0.
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