Small Pelvis, Big Baby
Picture from UnSplash
So, what is the evidence on big babies and small pelvises? What research can we as women do to help them when they are being told that they have a big baby and need to be induced early?
From the time women get pregnant, we have the fear of ‘how are we going to get this baby out of there?’, or we have the constant horror stories thrown at us of ‘my baby was on the 99th percentile and I ended up in caesarean’. Unfortunately, healthcare professionals can sometimes make this fear worse and threat of a caesarean can start looming over us when they start saying the words ‘failure to progress’. As we know, being labeled as ‘failure to progress’ can sometimes really mean ‘failure to wait’!
The medical word for a big baby is actually ‘macrosomia’ which translates to ‘big body’ and thankfully, when you start to actually investigate and research how birth and the pelvis works, it really can help alleviate fears around birthing a large baby. We need to stop looking at the worst case scenario and instead help support women achieve the birth they want and can achieve. Thankfully with more and more women looking at hiring Doulas and doing independent birth education, we are already half way there.
It is true that our pelvis has so much to do with our birth however it’s untrue that it is common that a baby will not be able to fit into our pelvis, which is medically known as cephalopelvis disproportion. In fact, CPD has been shown to occur in only 1 out of 250 pregnancies according to American Collage of Nurse-Midwives (www.midwife.org) and many women go on to birth without this recurring again. A study also shows that 68% of women diagnosed with absolute CPD in a previous pregnancy went on to have a vaginal birth in future (https://pubmed.ncbi.nlm.nih.gov/9794672/). CPD is also nearly impossible to diagnose before labour.
So, when we hear the words ‘big baby’, sometimes they can also be followed with the word ‘induction’. Although it’s the UK, it’s worth noting that The NICE (National Institute for Health and Care Excellence) recommendation statement says 'in the absence of any other indications, induction of labour should not be carried out simply because a healthcare professional suspects a baby is large for gestational age’ (https://www.nice.org.uk/donotdo/in-the-absence-of-any-other-indications-induction-of-labour-should-not-be-carried-out-simply-because-a-healthcare-professional-suspects-a-baby-is-large-for-gestational-age-macrosomic). Sadly, this advice doesn’t seem to be widespread. Depending on your health care professionals philosophies on large babies you may get gently (or not gently) recommended to look at being induced. Generally, they will list reasons such as baby will continue to becoming bigger and therefore you won’t have any chance to be able to birth vaginally or big babies can suffer injuries or trauma. Essentially, giving you all the worst case scenarios without really giving you the full picture.
Even if you do have a big baby, thankfully, pregnant pelvises are not fixed structures. Our body is incredible and with the hormones flowing through our body during pregnancy and labour, our pelvis and all the connecting ligaments, muscles and tendons will stretch ready to help the baby to move down the birth canal. Your pelvis actually moulds during labour and when labouring in different positions other then your back your pelvis can mould up to 30 per cent! Therefore your baby’s heads mould to fit perfectly down the birth path.. isn’t that incredible? The bones can even overlap during birth and in time will slow fuse together. The assumption that induction allows a baby to be born at a smaller weight and therefore avoid the issue of ‘not fitting’ is not entirely accurate. In a 2016 Cochrane review, researchers (Boulvain et al. 2016) combined four studies in which 1,190 non-diabetic pregnant people with suspected big babies were randomly assigned to either 1) induction between 37 and 40 weeks or 2) waiting for spontaneous labor. The results found that on average, babies weighed 178 grams (6 ounces) less when labor was electively induced, compared with those assigned to wait for labor. (https://evidencebasedbirth.com/evidence-for-induction-or-c-section-for-big-baby/). If it’s only such a small difference, why are we still using induction for this reason?
As well as that, if you have been told that your baby is measuring large, rest assured that there is actually no foolproof way of measuring your baby’s size, and to be frank, I think it’s wrong to put so much pressure on women regarding their babies size when the ultrasound reading can be inaccurate by up to 25 percent (https://utswmed.org/medblog/big-baby-birth/). So why is this inaccurate figure being used as a reason to induce labour?!Personally, I know of 3 women who basically got scared thinking they had a humongous baby and when baby came out, they were average or even on the smaller side and the fear was put into them for no reason. I have no doubt if you have been told you have a big baby you most likely have heard all the horror stories as well as what can go wrong however putting women in a negative mainframe for birth helps absolutely no one! It may also be worth asking your health care professional about the risks of induction for example how it may lead to your baby being born with immature organs.
There are many types of movements you can do to try and help baby get in the best position possible, which is the left occiput anterior position. This position means baby has their back on the mothers left side and faces towards the mothers back between the right hip and spine of mum. Ways to help baby get into this ideal position include sitting on a chair leaning forward, knee light upright, sitting upright or on your hands and knees. When you sit on a chair, keep an eye on how your knees are positioned, making sure they are lower than your pelvis. Spinning Babies (https://www.spinningbabies.com/pregnancy-birth/labor/is-baby-too-big) is a wonderful resource for many issues that come up in pregnancy and birth including this particular one regarding big bubbas! Another recommendation to help support your pelvis in preparation for childbirth is the ‘side lying release’ (https://www.spinningbabies.com/pregnancy-birth/techniques/side-lying-release/) which is a stretch to temporarily and slightly enlarge and soften the pelvis. Positions during labour birth are also so important - squatting, side lying or being on all fours creates optimal space for baby to descend. (https://www.bellybelly.com.au/birth/small-pelvis-big-baby-cpd/)
As a Doula, it my role to reassure mothers that their body was made for the baby they grew. As well as providing you with techniques on how to achieve optimal fetal positioning, there are also so many beautiful affirmations out there to really help us prepare for birth and going inwards to our own body. My favourites are:
My body grew my baby and knows how to birth my baby
My body grew a baby that is the right size for me
My body and pelvis open wide for my baby to pass through
My Levis releases and opens easily to make way for my baby
My body contains all the knowledge necessary to give birth to my baby
There are so many incredible birth stories out there that you can access through podcasts, Facebook groups or online that can help provide reassurance when it comes to having a big baby and birthing vaginally. I would recommend listening to podcasts such as Australian Birth Stories and VBAC Birth stories to provide some stories that may help you get your head around the different experiences women go through as well as women have handled issues that have come up during birthing. I will always recommend doing an independent child birth education course as well, in particular Hypnobirthing Australia.
And remember, if you are unsure and feel your healthcare professional is pushing you in a certain direction that you do not feel comfortable, always, always get a second opinion.
