A large-scale international study has shed light on how genetics influences the growth of the placenta. The results also show that faster growth of the placenta can contribute to the risk of preeclampsia in the mother and to earlier delivery of the baby.
The University of Eastern Finland’s Physical Activity and Nutrition in Children (PANIC) study took part in this international collaboration. “This study is scientifically unique as the first genome-wide association study on placental weight at birth, and it is also important from clinical perspective by showing that faster placental growth increases the risk of preeclampsia in the mother,” says Professor Timo Lakka, the leader of the PANIC study.
Involving researchers from Europe, Australia, Canada and the United States and led by the universities of Exeter, Bergen and Copenhagen, the study examined placental growth in the greatest detail yet. They carried out the first ever genome-wide association study of placental weight at birth. The findings were published in Nature Genetics.
The placenta is an organ which grows in the womb alongside the foetus. Via the umbilical cord, the placenta provides oxygen and nutrients to the growing foetus and removes waste. A poorly functioning placenta is associated with pregnancy complications, and later risk of disease in the child. Despite its key role, little is yet known about how the growth of the placenta is regulated. Understanding placental growth is important, as babies with very small or large placentas are at higher risk of complications.
The study identified 40 variations in the genetic code linked to how big a placenta can grow. Several of these genetic variations also influence the weight of the baby.
The research team found that where the genetic code of the foetus meant it was more likely that the placenta would grow bigger, there was a higher risk of pre-eclampsia in the mother. This could be because the placenta grows too fast, which can upset the balance between the baby’s demand for resources and how much the mother is able to provide, which can be a factor in pre-eclampsia that occurs later in pregnancy.
Pre-eclampsia is a condition that may develop in pregnancy, causing high blood pressure. Some of the mother’s organs, such as the kidneys and liver, stop working properly. Detecting it early is essential to avoid severe health problems for mother and baby, yet how preeclampsia develops isn’t fully understood. This large-scale international study suggests that faster growth of the placenta contributes to a higher risk of preeclampsia in the mother. It seems specific to placenta growth because the researchers did not find the same risk when they looked at the genetics of baby weight.
Faster-growing placenta was also linked to shorter pregnancy. Babies with genetic code for a bigger placenta were more likely to be born earlier.
One key finding from the study related to insulin, which regulates blood sugar. The foetus produces insulin in response to glucose from the mother, which acts as a growth factor. Insulin was also linked to the growth of the placenta, which helps to explain why placentas tend to be large in pregnancies where the mother has high blood glucose due to diabetes.
For further information, please contact:
Professor Timo Lakka, https://uefconnect.uef.fi/en/person/timo.lakka/
Research article:
Beaumont RN et al. Genome-wide association study of placental weight identifies distinct and shared genetic influences between placental and fetal growth. Nat Genet. 2023 Oct 5. doi: 10.1038/s41588-023-01520-w. Epub ahead of print. PMID: 37798380. https://pubmed.ncbi.nlm.nih.gov/37798380/
