Breech Inheritance: the flip side

Is being breech a genetic thing? Nordtveit et al (2008) conducted a fascinating study looking at whether being breech is genetic, or an inherited trait. They analysed Norwegian birth registry records in order to research whether breech presentation at term recurs between generations. Their results showed that the first children of both mothers and fathers who were breech at birth were more than twice as likely to be breech as the first children of parents who had been in a cephalic presentation at birth. Although we already knew that breech presentation is likely to recur among babies born to the same mother (Albrechtsen et al 1998) the inheritance question has not previously been studied in this way. The fact that fathers were shown to have just as much influence on breech presentation as mothers adds further weight to the suggestion that breech presentation may have a genetic component.

 

And this means that…?

As is often the case, the conclusions drawn about the findings of a study are just as interesting as the findings themselves. The authors of this study conclude that gathering information about the birth presentation of the mother and father may help in assessing presentation and avoid unexpected breech births. Hardy (2008), who was asked to commentate upon this paper, urges caution. She feels it may be premature to advise mothers that a parent having been breech increases the likely-hood of breech presentation, on the basis that more evidence is needed in this area. She does, however, argue that it remains useful to gather information about the presentation of the baby’s parents so that, if breech presentation is suspected during pregnancy, external cephalic version and / or caesarean section can be discussed.

Either way, the focus continues to be placed upon the idea that breech babies are “at risk” and that they are better off either being turned or being cut out of their mothers. Studies do show that breech babies have higher perinatal mortality and morbidity than their cephalic counterparts (Danielian et al 1996), but this data does not give a full picture. Some babies, for instance, may present by the breech because they have morbidity. The data is also limited because, although we know that breech-presenting babies do not fare well under obstetric management by comparison to cephalically presenting babies, we do not have enough data about breech babies whose births are attended by midwives working in a more holistic manner and with a focus on supporting physiological birth to know whether this is a safer option.

 

What else could it mean?

The kind of study that Nordtveit et al undertook is great for telling us that something happens, but it can’t tell us why it happens or what the implications of it happening are. This is, of course, one of the reasons why we need to use other forms of knowledge in practice. But the answers to those “why?” and “so what?” questions depend partly upon the ideology of the person or group who is considering them. We already know how the medical model perceives the issue of breech birth. What would midwives say?

One of the things that midwives sometimes talk about is whether some babies choose to be breech, maybe because it confers an advantage to them. This study raises a number of questions like this, including whether breech birth might be ‘the norm’ for some families. We can only speculate as to why this might be, but perhaps the women of these families have interesting anatomy which enables them to give birth to breech babies more easily than cephalic babies? Or perhaps it is better for the baby? Given that obstetric intervention is relatively recent; if physiological breech birth was that dangerous then these families surely wouldn’t have managed to survive in such numbers? We know that some babies may be breech because they have a problem. Is it so far fetched to think that some babies may also be breech because it confers an advantage?

We could also look more critically at what we do when we discover a breech baby. (I don’t like the way that we talk about “diagnosing” breech babies. Diseases are diagnosed, and neither babies nor the positions they lie in are diseases). If some breech babies are sitting in a breech position because this is how babies like to sit in their family, then what is the implication of continuing to try and turn or cut out breech babies? Are we denying these babies their birthright, or perhaps even putting them at greater risk by making them turn around?

These are only the first few questions that came into my head when I read this paper. I’m sure that others can think of better and more interesting ones, and I really hope that they do, because we really need to get beyond the usual round of risk focused discussion that this kind of article tends to generate and think about what it might mean from a range of perspectives.

 

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A version of this article was originally published as Wickham S (2008). Breech Inheritance: the flip side. TPM 11(6):56.

 

References

Albrechtsen S, Rasmussen S, Dalaker K, Irgens LM (1998). Reproductive career after breech presentation: subsequent pregnancy rates, interpregnancy interval, and recurrence. Obstetrics and Gynecology 92: 345-50.

Danielian PJ, Wang J, Hall MH (1996). Long-term outcome by method of delivery of fetuses in breech presentation at term: population based follow up. BMJ 312: 1451-53.

Hardy, JR (2008) Intergenerational recurrence of breech delivery BMJ, Mar 2008; doi:10.1136/bmj.39527.608542.80

Nordtveit TI, Melve KK, Albrechtsen S and Skjaerven R (2008). Maternal and paternal contribution to intergenerational recurrence of breech delivery: population based cohort study. BMJ, Mar 2008, doi:10.1136/bmj.39527.608542.80

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