BMJ：婴儿臀位出生可能有遗传性

《英国医学杂志》（BMJ）3月28日发表论文说，如果父母一方或双方以臀部先出来的方式出生，其新生婴儿臀部先出来的几率为一般人的2倍。

这一结论由挪威卑尔根大学的调查者得出。他们研究了1967年至2004年间出生的所有婴儿的数据，并拿这些数据与可获取的所有有关男性、女性及其头胎婴儿的数据做比较。这些数据相当于比较了23.2万对母亲与孩子和15.4万对父亲与孩子。

比起头部先出的方式，臀位出生导致婴儿死亡或有健康问题的风险更高。不到5%的婴儿以臀部先出的方式出生。

《英国医学杂志》周刊说，如果父母是以臀部先出来的方式出生，医生还需要收集更多遗传证据，然后才能向孕妇发出婴儿会以同样方式出生的警告。

原始出处：

（BMJ），doi:10.1136/bmj.39505.436539.BE，Tone Irene Nordtveit, Rolv Skjaerven

Maternal and paternal contribution to intergenerational recurrence of breech delivery: population based cohort study

Tone Irene Nordtveit, PhD student¹, Kari Klungsoyr Melve, associate professor^1,2, Susanne Albrechtsen, obstetrician³, Rolv Skjaerven, professor^1,2

¹ Section for Epidemiology and Medical Statistics, Department of Public Health and Primary Health Care, University of Bergen, Postbox 7804, N-5020 Bergen, Norway, ² Medical Birth Registry, Norwegian Institute of Public Health, Norway, ³ Department of Obstetrics and Gynaecology, Haukeland University Hospital, N-5021 Bergen, Norway

Objective To investigate intergenerational recurrence of breech delivery, with a hypothesis that both women and men delivered in breech presentation contribute to increased risk of breech delivery in their offspring.

Design Population based cohort study for two generations.

Setting Data from the medical birth registry of Norway, based on all births in Norway 1967-2004 (2.2 million births).

Participants Generational data were provided through linkage by national identification numbers, forming 451 393 mother-offspring units and 295 253 father-offspring units. We included units where both parents and offspring were singletons and offspring were first born, forming 232 704 mother-offspring units and 154 851 father-offspring units for our analyses.

Main outcome measure Breech delivery in the second generation.

Results Men and women who themselves were delivered in breech presentation had more than twice the risk of breech delivery in their own first pregnancies compared with men and women who had been cephalic presentations (odds ratios 2.2, 95% confidence interval 1.8 to 2.7, and 2.2, 1.9 to 2.5, for men and women, respectively). The strongest risks of recurrence were found for vaginally delivered offspring and were equally strong for men and women. Increased risk of recurrence of breech delivery in offspring was present only for parents delivered at term.

Conclusion Intergenerational recurrence risk of breech delivery in offspring was equally high when transmitted through fathers and mothers. It seems reasonable to attribute the observed pattern of familial predisposition to term breech delivery to genetic inheritance, predominantly through the fetus.