The truth about birthing a big baby

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When told that they are having a 'big baby', many women have a lot of fears: that they won't be able to have a natural birth, that they'll need an induction or caesarean, that it means there's something wrong with their bub.

So what exactly is a 'big baby'? Newborns in this category generally weigh in the 90th percentile or greater for gestational age, or are just over 8.8 pounds (3.99kg). And no, it doesn't all mean bad news - the myths can be very wrong.

Myth 1: Women who have big babies must have gestational diabetes

While there is a correlation between high blood sugar and bigger babies, many women who have big babies have ordinary glucose test results and don't have gestational diabetes. So a big baby does not necessarily mean you'll have gestational diabetes.

Myth 2: Natural birth is harder and more problematic with big babies

A suspected big baby is not really an evidence-based reason for induction or a C-section.

When it comes to birthing big babies, there's a common fear that the shoulders can get stuck (shoulder dystocia). But this occurs very rarely – in about 6.5 cases out of 1000 births.

Birth position can really make a difference, and being on all fours is ideal for expanding the pelvis to help the baby out smoothly. While women are often depicted as birthing on their backs - it's easier for the practitioner, and easier for TV shows - lying flat can reduce a woman's pelvic capacity by 30 per cent. When a woman is free from drips, monitors and numbness from an epidural she will instinctively move into a gravity-assisting position.

Mira, mum of a 10.2lb (4.6kg) baby says she alternated between being on all-fours and lying down. Similarly, Lisa, mum of a 9.14lb (4.14kg) baby said she spent most of her labour standing.


Birthing while squatting can also help; Natalie, mum of a 9.1lb (4.13kg) baby, says that she used a birthing ball in her unplanned homebirth, and her baby came out easily with minimal pain. Natalie says the key was trusting her body:"I never viewed my baby as being a 'big' baby, or felt concerned. I always believed that my body was able to do the job".

Myth 3: We can accurately predict a big baby

There is no completely accurate way to predict a big baby - the accuracy of an ultrasound to predict size may even be less than 50 per cent. For every 10 babies that ultrasounds predict will weigh greater than 8.13lb (3.68kg), five babies will weigh more than that, and the other five will weigh less..

Myth 4: Women need intervention to keep the baby from getting any bigger

In some cases intervention might be what's best for mum and baby, but it should be evidence-based. And yes, sometimes women are encouraged to be induced or have a caesarean so the baby doesn't get any bigger.

A good practitioner will not make suggestions out of frustration, impatience, of lack of confidence in the mum's ability to birth. Mums don't need to feel judged about how they give birth - and most importantly, they don't need to feel anxious.

Lisa, who is now 30 weeks pregnant with her third baby, says she found the way she was treated frustrating. "Despite previously vaginally birthing two 9.14lb (4.15kg) healthy baby boys, there were those who thought I should opt for a C-section this time around," she says. "I was given little credit for my previous labours and efforts to naturally birth my babies."

Fortunately, not all health practitioners share this view. Mira's baby was actually 1.5lb (680g) bigger than expected, but wasn't pressured to be induced or have a C-section.

Natalie says there was no speculation about a 'big' baby when she was pregnant either; she chose a practice with a low c-section rate, and was never coerced into needing intervention.

Trust and confidence in a woman's ability to birth makes a huge difference - as famed midwife Ina May Gaskin points out, humans are the only mammal to doubt their capacity to give birth.

Reducing birth fears

1. Research. Birth is like a marathon. You wouldn't turn up to run 10km without any preparation and hope for the best; preparation boosts confidence, thereby reducing fear and pain during labour.
2. Ignore the horror stories. Focus on positive, confidence-boosting messages about birth.
3. Exercise. Building strength and stamina helps with overall health, but also with being able to sustain a gravity-assisted position.
4. Consider hypnobirthing. It's a fancy way of saying 'deep relaxation', but it's evidence-based, and the techniques are powerful. There is a direct connection between fear and the sensation of pain. Contact for information.