Will my placenta start to fail at 42 weeks?

When a pregnancy reaches 42 weeks, a LOT of pressure is put on a mother and she is expected to make some huge decisions regarding her baby, and in many circumstances, she may not be presented with all the evidence she needs to be making those decisions.

Ticking clock 42 week

I recently discussed the ridiculous origins of your due date, and how crazy it is to be suggesting a myriad of interventions to women based on that one date.

And today I want to discuss your placenta. You may not know much about it, other than it is keeping your baby alive so here are some.....

Interesting facts about your placenta:

  • Your placenta provides your baby with all the nutrients, oxygen and fluids that he or she needs.
  • Although it is often thought of as a mother’s organ, the placenta is formed from the same cells as your baby, so both mum and dad.
  • Your placenta can be blamed (at least in part) for your hormonal rollercoaster! It is acting as a gland and secreting all the important hormones your baby needs to grow and develop, and preparing your body for breastfeeding.
  • Even when you’re chilling out, your placenta is working extremely hard taking blood from your uterus which carries the nutrients your baby needs. No wonder you are so tired all the time!
  • Your placenta is providing all your baby’s oxygen. This is why I tell all the mums at my pregnancy yoga classes “You don’t need to eat for 2, but you need to breathe for 2!”
  • Your placenta is designed to be disposable, it serves its purpose and is then expelled from the body…..and although consuming your placenta has no proven benefits, there are many anecdotal benefits.
Photo by treeoflifebirthphotography.com

Photo by treeoflifebirthphotography.com

So now you know how amazing it is, we need to talk about what happens to your placenta at the end of your pregnancy. Some of you may have been told that at 42 weeks, your placenta begins to deteriorate, often called ‘placental insufficiency’.

So what is the evidence for this?


Nothing more than speculation, an educated guess.

Theories, of course, have their uses and they are what ultimately leads to scientific breakthroughs, but let’s not forget all the theories which have been proven incorrect and are now considered absurd.

A theory should form the basis of further research, to gather evidence that either proves or disproves the assumptions. It shouldn’t form the basis of policies that affect millions of women, when there is no proof!

“There is no evidence that shows a direct correlation between the quality of the placenta, and the length of pregnancy” (1)

“A review of the available evidence indicates that the placenta does not undergo a true aging change during pregnancy. There is, in fact, no logical reason for believing that the placenta, which is a fetal organ, should age while the other fetal organs do not” (2)

This doesn’t mean that placental insufficiency doesn’t exist, but it does mean that you should be treated as an individual. Assuming that all placentas deteriorate at 42 weeks means that lots of women are put through unnecessary intervention, but most importantly it might mean that cases of placental insufficiency prior to 42 weeks are missed because it isn’t expected to happen at that point.

What can you do to help your placenta function well?

There is very little evidence in this area, but here are some things you can do which will help blood flow to the placenta and increase oxygen levels for baby:

  • Eat a healthy, balanced diet rich in nutrients for both you and baby
  • Stop smoking (liaise with your midwife about this)
  • Reduce anxiety and stress with regular relaxation. Yoga and hypnobirthing can help with this.
  • Stay hydrated
  • Massage can help with relaxation and blood circulation
  • Practice deep breathing - again you will learn this on my yoga or hypnobirthing courses
Fresh fruit and veg

One final note

Take responsibility for your birth. Ask questions, demand evidence, get the answers you need to make informed decisions. You are an individual and you deserve to be treated as one.

Kicks count

Always trust your instincts, keep track of your baby’s movements and report anything unusual to your midwife.

Please be aware that there are conditions which may affect placental function such as gestational diabetes(3) so it is important you discuss with your midwife how this will be managed.

1 [Sara Wickham (2016), ‘Post Dates Pregnancy Course’]
2 [Fox H (1997), ‘Aging of the placenta’, published in the British Medical Journal]
3 [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3215769/]