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Neonatal hip instability and intrauterine factors

Study
Results
Comment

A mum-to-be has heard that vaginal delivery of a baby with a breech presentation leads to hip problems. Is that true or false? It is comforting to know that an enormous and comprehensive survey from Norway [1] gives us some real numbers to inform her what the risks are.

Study


Since 1967, every baby born in Norway has information recorded about maternal and neonatal health. That means that between 1970 and 1988 there was comprehensive information available on 1,059,479 newborns, with data on birth weight, sex, birth order, gestational age, mode of presentation, and delivery. The registry also has information about neonatal hip instability, together comprising congenital dislocation and sign of Ortolani (a good description of diagnostic tests can be found at www.aap.org/policy/ac0001.htm ).

This comprehensive data set was examined for relationships between maternal and neonatal factors, and the chance of a baby having neonatal hip instability.

Results


There were 9,955 cases of neonatal hip instability in 1,046,000 live births, a prevalence at birth of 1%. After allowing for some stillbirths, multiple births and missing data, information was available for analysis on just under 960,000 babies.

Prevalence in female and male children at any gestational age was low, at less than 1% with vertex presentation. For breech presentation prevalence was higher, and especially related to gestational age and female sex with the first baby (Figure 1).

Figure 1: Neonatal hip instability for first and subsequent births by gestational age in weeks with breech presentation



The prevalence of neonatal hip instability was lower at 0.26% in babies weighing less than 2,500 grams. For vertex or breech presentation, the prevalence was the same if delivery was vaginally or by Caesarean section.

Comment


So mum can be reassured that vaginal delivery will not increase the risk of neonatal hip instability if her baby has a breech presentation. The rest of us can be astounded by the huge amount of information on which this was based. There were 41,500 babies weighing less than 2,500 grams. There were 47,600 babies with vertex presentation delivered by Caesarean section. There were just under 24,000 breech presentations (2.5% of the total, a chance of 1 in 40) and 15,800 delivered vaginally and 8,000 by Caesarean section.

Vision multiplied by effort multiplied by quality and consistency makes for a potent brew. Recording what happens really should not be so difficult with a few little computers. It can really help drive professional and personal decision-making.

References:

  1. T Hinderaker et al. The impact of intra-uterine factors on neonatal hip instability. An analysis of 1,059,479 children in Norway. Acta Orthop Scand 1994 65: 239-242.
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