A University of Sydney study entitled “Are babies getting bigger? An analysis of birthweight trends in New South Wales, 1990–2005” that cost $134,500 revealed that the weight of babies increased by 23g in girls and 25g in boys. For those who don’t think metric, that means babies weigh just 0.05 pounds or 0.8 ounces more.

The study looked at many explanatory variables available for analysis included infant sex, maternal age, parity, smoking during pregnancy, pre-existing diabetes, gestational diabetes, hypertensive disorders during pregnancy, and maternal region of birth and year of birth.

Also noted in the study was the following:

The trend in mean birthweight for babies of women who underwent elective caesarean section and induction of labour was similar to the trend for those without these interventions.

The study came to my attention in yesterday’s Sydney Morning Herald article, “Health risks increase as newborns get heavier.” The article states:

Bigger babies also caused problems during delivery, contributing to more caesarean births, postpartum haemorrhage, perineal lacerations and complications such as shoulder dystocia, where the shoulders of the baby get stuck in the birth canal.

Once again, the story is not the research. The story is the bizarre obsession with promoting the BIG! BABIES! ARE! DANGEROUS! myth which is a cornerstone in the foundation of obstetric management of pregnancy and childbirth.

Cue public panic and watch doctors sigh in relief and feel justified in their choice to section so many women. Those .05 pounds per baby clearly justify a 25% or higher c-section rate.

Note: In the time it took me to post this, Lauredhel from Hoyden About Town broke down the fat baby epidemic that isn’t.



Fortunately, research is being conducted on care provider bias and the shortcomings of “bedside” ultrasound estimate of fetal size while in labor. According to this new study, there may be a relationship between an overestimate of fetal weight by ultrasound and likelihood that a doctor will diagnose a woman with labor arrest and perform a c-section.

Here’s the abstract:

Overestimation of fetal weight by ultrasound: does it influence the likelihood of cesarean delivery for labor arrest?

Sean C. Blackwell MD, Jerrie Refuerzo MD, Rati Chadha MD and Carlos A. Carreno MD

Division of Maternal Fetal Medicine, Department of Obstetrics, Gynecology and Reproductive Sciences, University of Texas Health Science Center at Houston, Houston, TX, Foothills Medical Center, University of Calgary, Calgary, AB, Canada



We sought to determine whether the overestimation of ultrasound-derived estimated fetal weight (EFW) is associated with increased diagnosis of labor arrest.

Study Design

This is a historical cohort study of nulliparous women with term pregnancies who underwent bedside ultrasound examination for EFW before labor induction. Labor outcomes of women with EFW overestimation > 15% the actual birthweight were compared with those with EFW not overestimated.


Overestimation of EFW occurred in 9.5% of cases (23/241). The rate of cesarean delivery (CD) for labor arrest was higher for those with EFW overestimation (34.8% vs 13.3%; P = .01) even though there were no differences in length of the induction duration. After adjusting for confounding factors, EFW overestimation remained associated with CD for labor arrest (odds ratio, 4.8; 95% confidence interval, 1.5-15.2).


Our finding suggests that an overestimation of EFW may be associated with a lower threshold for CD for labor arrest.





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