Research Suggests Breech Births Might Be Linked to Heredity

If you ask women pregnant for the first time what their greatest concerns are, most will mention having a breech baby or a Cesarean section.

A breech delivery is actually twice as common when either parent was a breech baby, according to MedPage Today. It occurs when a baby is born feet- or bottom-first instead of head-first. Cesarean sections are usually the delivery method of choice in such situations.

A recent study headed by Tone Irene Nordtveit, a Norwegian doctoral student in epidemiology, adjusted the odds ratio for a breech delivery to 2.2 when mom or dad was a first-born breech. These numbers suggest a genetic component linked to breeched births, although no specific cause was determined. The study was funded by the Norwegian Medical Research Council.

The researchers took a look at all Norwegian birth records for the period of 1967 to 2004, or about 2.2 million births. They found that when both parents had been breech deliveries, the adjusted odds ratio that their son or daughter would be born via a breech presentation went up to 3.1. However, when the breech parent was not a first-born, the risk of his offspring being a breech baby was reduced slightly.

Statistics reported suggested that the genetic contribution from the father might be the more important one in determining whether a baby will be born via a breech delivery. This conclusion was bolstered when Nordveit and fellow researchers studied offspring of individuals who had fathered children with two different women.

Of the 2.2 million births studied, 5,661 occurred to mothers who had been breech babies themselves. These mothers then gave birth to 449 breech babies (7.6 percent). By contrast, 4.1 percent of the babies born mothers who had been cephalic births were born via breech presentations. The percentages for breech-born fathers were nearly the same.

In general, scientists figured around six percent of all Norwegian breech births were due to parental influence. The births studied included both vaginal and Caesarean deliveries.