Auger Nathalie, Daniel Mark, Platt Robert W, Luo Zhong-Cheng, Wu Yuquan, Choinière Robert
Unité Etudes et analyses de l'état de santé de la population, Institut national de santé publique du Québec, Montréal, Québec, Canada.
BMC Pregnancy Childbirth. 2008 Feb 28;8:7. doi: 10.1186/1471-2393-8-7.
Interpregnancy interval (IPI), marital status, and neighborhood are independently associated with birth outcomes. The joint contribution of these exposures has not been evaluated. We tested for effect modification between IPI and marriage, controlling for neighborhood.
We analyzed a cohort of 98,330 live births in Montréal, Canada from 1997-2001 to assess IPI and marital status in relation to small for gestational age (SGA) birth. Births were categorized as subsequent-born with short (<12 months), intermediate (12-35 months), or long (36+ months) IPI, or as firstborn. The data had a 2-level hierarchical structure, with births nested in 49 neighborhoods. We used multilevel logistic regression to obtain adjusted effect estimates.
Marital status modified the association between IPI and SGA birth. Being unmarried relative to married was associated with SGA birth for all IPI categories, particularly for subsequent births with short (odds ratio [OR] 1.60, 95% confidence interval [CI] 1.31-1.95) and intermediate (OR 1.48, 95% CI 1.26-1.74) IPIs. Subsequent births had a lower likelihood of SGA birth than firstborns. Intermediate IPIs were more protective for married (OR 0.50, 95% CI 0.47-0.54) than unmarried mothers (OR 0.65, 95% CI 0.56-0.76).
Being unmarried increases the likelihood of SGA birth as the IPI shortens, and the protective effect of intermediate IPIs is reduced in unmarried mothers. Marital status should be considered in recommending particular IPIs as an intervention to improve birth outcomes.
妊娠间隔（IPI）、婚姻状况和邻里环境均与出生结局独立相关。尚未评估这些因素的联合作用。我们在控制邻里环境的情况下，检验了IPI与婚姻之间的效应修正。
我们分析了1997 - 2001年加拿大蒙特利尔的98330例活产队列，以评估IPI和婚姻状况与小于胎龄（SGA）儿出生的关系。分娩被分类为IPI短（<12个月）、中等（12 - 35个月）或长（36个月及以上）的经产妇，或初产妇。数据具有两级层次结构，分娩嵌套在49个邻里环境中。我们使用多水平逻辑回归来获得调整后的效应估计值。
婚姻状况修正了IPI与SGA儿出生之间的关联。相对于已婚者，未婚与所有IPI类别中的SGA儿出生相关，尤其是IPI短（比值比[OR] 1.60，95%置信区间[CI] 1.31 - 1.95）和中等（OR 1.48，95% CI 1.26 - 1.74）的经产妇。经产妇发生SGA儿出生的可能性低于初产妇。中等IPI对已婚母亲（OR 0.50，95% CI 0.47 - 0.54）比对未婚母亲（OR 0.65，95% CI 0.56 - 0.76）的保护作用更强。
随着IPI缩短，未婚会增加SGA儿出生的可能性，且中等IPI对未婚母亲的保护作用减弱。在推荐特定的IPI作为改善出生结局的干预措施时，应考虑婚姻状况。
