Rohr Thomsen Christine, Uldbjerg Niels, Hvidman Lone, Atladóttir Hjördís Ósk, Henriksen Tine Brink, Milidou Ioanna
Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby, Aarhus, Denmark.
Department of Pediatrics, Aarhus University Hospital, Skejby, Aarhus, Denmark.
PLoS One. 2014 Apr 15;9(4):e94432. doi: 10.1371/journal.pone.0094432. eCollection 2014.
Dystocia is one of the most frequent causes of cesarean delivery in nulliparous women. Despite this, its causes are largely unknown. Vitamin D receptor (VDR) has been found in the myometrium. Thus, it is possible that vitamin D affects the contractility of the myometrium and may be involved in the pathogenesis of dystocia. Seasonal variation of dystocia in areas with distinct seasonal variation in sunlight exposure, like Denmark, could imply that vitamin D may play a role. This study examined whether there was seasonal variation in the incidence of dystocia in a Danish population.
We used information from a cohort of 34,261 nulliparous women with singleton pregnancies, spontaneous onset of labor between 37 and 42 completed gestational weeks, and vertex fetal presentation. All women gave birth between 1992 and 2010 at the Department of Obstetrics and Gynecology, Aarhus University Hospital, Skejby. Logistic regression combined with cubic spline was used to estimate the seasonal variation for each outcome after adjusting for calendar time.
No evidence for seasonal variation was found for any of the outcomes: acute cesarean delivery due to dystocia (p = 0.44); instrumental vaginal delivery due to dystocia (p = 0.69); oxytocin augmentation due to dystocia (p = 0.46); and overall dystocia (p = 0.91).
No seasonal variation in the incidence of dystocia was observed in a large cohort of Danish women. This may reflect no association between vitamin D and dystocia, or alternatively that other factors with seasonal variation and influence on the occurrence of dystocia attenuate such an association.
难产是初产妇剖宫产最常见的原因之一。尽管如此，其病因在很大程度上仍不清楚。已在子宫肌层中发现维生素D受体（VDR）。因此，维生素D有可能影响子宫肌层的收缩力，并可能参与难产的发病机制。在阳光照射有明显季节性变化的地区，如丹麦，难产的季节性变化可能意味着维生素D可能起作用。本研究调查了丹麦人群中难产发生率是否存在季节性变化。
我们使用了来自一个队列的34261名单胎初产妇的信息，这些产妇在妊娠37至42周时自然发动分娩，且胎儿为头先露。所有妇女于1992年至2010年在奥胡斯大学医院斯基比妇产科分娩。在调整日历时间后，采用逻辑回归结合三次样条函数来估计每个结局的季节性变化。
对于任何结局均未发现季节性变化的证据：因难产行急症剖宫产（p = 0.44）；因难产行器械助产阴道分娩（p = 0.69）；因难产使用缩宫素加强宫缩（p = 0.46）；以及总体难产（p = 0.91）。
在一大群丹麦妇女中未观察到难产发生率的季节性变化。这可能反映出维生素D与难产之间无关联，或者其他具有季节性变化且影响难产发生的因素减弱了这种关联。
