"I've been told my baby is big"

and my care provider wants to induce me / schedule a caesarean.

An interesting dilemma. What to do? A recent article has found that ultrasound diagnosis of fetal macrosomia (a big baby) at term is inaccurate in the majority of cases, and this inaccuracy may be contributing to unnecessary caesarean sections.

In an observational cohort study of 235 pregnancies at term in which ultrasound measurements led to a diagnosis of fetal macrosomia, only about a third of the infants were actually macrosomic at birth. Additionally, these pregnancies with ultrasound-diagnosed fetal macrosomia were more than twice as likely as all pregnancies in the population to end in cesarean delivery

Surprisingly, the accuracy of ultrasound in assessing fetal weight is similar to that found with simple clinical palpation (feeling the size of the baby through the woman's abdomen)

The [average] percentage error of the estimated fetal weight was 8.6% overall. Viewed another way, 44% of the weights were off by more than 10%, and 7% were off by more than 20%.

The mode of delivery was cesarean section in 66% of the pregnancies, compared with just 29% of all pregnancies in Calgary during the same period. "So it’s [more than] double, the percentage who are getting C-sections, on what is [an inaccurate weight]

It's a difficult situation for the care provider when considering what to say to a pregnant woman. Tell any woman her baby might be "big" and she'll rightly be scared. And this fear can impact the birth and lead to interventions. Conversely, is it ok to say, "Your baby is the perfect size for your pelvis and you'll birth your baby beautifully"? What if it doesn't quite work out this way for this woman?

I like to let women know that size isn't everything. We all know this! The position of the baby is also really important as is the strength of the contractions, a woman's morale and motivation, her support team, and the decisions she'll make with her care provider.

A woman can have a "small" posterior baby that results in a long labour ... or a "large" but well positioned baby that results in a smooth and easy labour. I've known many women to have a caesarean with their first baby - women will say, "He didn't fit. It was a long labour and I only got to 4cm and he was only 3.4Kg" and they go on to have a 4kg baby next time in a four hour labour with no tears.

My feeling is that it is ok to let a woman know that her baby feels like it might be larger than expected so that the woman can proactively plan for her labour with things like upright positions in labour, positions that open the pelvis and positions that help her to relax. It's always important to be truthful as this builds trust. It's also really important to talk about the position of the baby as I often find that a baby's position in labour is more important than its size. It's not about creating fear and disappointment by suggesting, "Your baby is h.u.g.e ... you'll need a caesarean for sure. In fact, why don't we book it in now and you can save yourself hours of labour only to end up with a caesarean?" But rather to explain that the baby feels larger than expected, that babies grow at different rates and that size is not the only important factor. And then work with her to help her to understand positions and strategies that will help her through her labour. In my own practice, only 4% women having their first babies have a caesarean, compared with 25% as the National average for first-time mums. I wonder how many caesareans can be avoided by providing continuity of care for women through pregnancy, birth and the new parenting experience?

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