Between day 5 and 8 after your egg is fertilised the developing ball of cells attaches itself to the wall of your uterus. When this happens the some of the cells will start to burrow into the lining of your uterus. These will become your placenta, while others become the sac (membranes) that your baby grows inside.
The placenta is the source of nutrition, oxygen and energy for your baby. It also removes waste products from your baby’s blood and transports it back to the mother’s circulation to dispose of via the umbilical cord. A mothers and baby’s blood do not generally mix. However, they do pass by close enough for substances and gasses to transfer between them. This happens through the walls of tiny blood vessels.
The placental clock
Your membranes, your placenta and your baby all stem from the same clump of cells. The formation of these started with conception. Therefore, your placenta will have the same DNA as your baby. It is, in a way, one of your baby’s organs. It is just required by your baby to function on the outside of its body. However, it is not designed to live beyond your baby’s birth, and placental function can start to decline before your baby is born. As you reach full-term (or beyond) the placenta can begin to show signs of ageing.
As any organism ages its ability to reproduce its cells and to produce energy and remove waste slows down. In the placenta, any drop in function can have an effect on the baby. Research has found that the placenta has its own “clock” – a self-limiting life span that appears to be responsible for the dramatic increase in the risk of stillbirth after 42 weeks of pregnancy. However, as each placenta is as individual as the baby, it is impossible to tell how fast that clock is ticking.
Induction of labour
This is one of the main reasons an induction of labour is recommended as you approach 42 weeks pregnant. While some placentas are still healthy and functioning well when you reach this gestation, others are not. They may not have been functioning well for several weeks. Sometimes an ultrasound scan can tell if a placenta isn’t functioning well. Other times it is a baby who isn’t growing as we would expect that alerts us to a problem. Sometimes it may be a baby who isn’t moving like they normally would. But sometimes we really don’t know.
As with all interventions please do your homework. Induction has risks as well as benefits. If you require further information before you consent to induction please ask questions. If you decide you don’t want to be induced we can monitor the health of your baby a variety of ways. A normal CTG is usually a good indication that your baby is healthy and well.
While your baby appears to be well regular monitoring, risk assessment and counselling will keep everybody’s concerns at bay. However, if your baby is showing signs of not coping your carer will talk to you about the increased risk and discuss your options again. If you change your mind an opt for induction that’s ok too. Health care providers are well aware of the risks of post-mature pregnancy and will be more than willing to accommodate your change of heart.
Dr Janelle McAlpine (PhD), Clinical Midwife
Photo by Dr Janelle McAlpine, used with permission from parents
Maiti K, Sultana Z, Aitken RJ, Morris J, Park F, Andrew B, Riley SC, Smith R. Evidence that fetal death is associated with placental aging. American journal of obstetrics and gynecology. 2017 Oct 1;217(4):441-e1.