What are the implications of having a "big" baby?

An ultrasound during pregnancy informs a prediction of estimated fetal weight. Midwifery lecturer Cara Baddington and former colleague George Parker reviewed the literature, and found that the estimated weight is often wrong. Some women who are predicted to have large babies do not, and conversely some women have a large baby when that was not predicted. It is not known how parents feel about being given an incorrect prediction that they are having a large baby.

A prediction of a large baby has implications for the pregnancy and birth care pathway, because the birth is perceived as higher risk. For example, the preferred birthing facility may not be available. Women giving birth to babies predicted to be large are more likely to have a medical intervention, such as early induction or elective caesarean, even though some of these babies are not in fact large. Cara and George also identified that these interventions for the births of predicted large babies may not result in improvement in the outcomes for the women and their babies, when compared with the outcomes for the births of large babies who were not predicted to be large.

To ensure that expectant parents can make informed decisions, midwives need to tell them about the limited accuracy of estimated fetal weight, and about the possibility that interventions do not guarantee improved outcomes and carry their own risks. 

August 2021