Section for Social Medicine, Department of Public Health, University of Copenhagen, Øster Farimagsgade 5, Postbox 2099, 1014, Copenhagen K, Denmark.
Department of Public Health, Section for Epidemiology, Aarhus University, Aarhus, Denmark.
Eur J Epidemiol. 2017 Sep;32(9):751-764. doi: 10.1007/s10654-017-0323-2. Epub 2017 Oct 12.
Women who drink light-to-moderately during pregnancy have been observed to have lower risk of unfavourable pregnancy outcomes than abstainers. This has been suggested to be a result of bias. In a pooled sample, including 193 747 live-born singletons from nine European cohorts, we examined the associations between light-to-moderate drinking and preterm birth, birth weight, and small-for-gestational age in term born children (term SGA). To address potential sources of bias, we compared the associations from the total sample with a sub-sample restricted to first-time pregnant women who conceived within six months of trying, and examined whether the associations varied across calendar time. In the total sample, drinking up to around six drinks per week as compared to abstaining was associated with lower risk of preterm birth, whereas no significant associations were found for birth weight or term SGA. Drinking six or more drinks per week was associated with lower birth weight and higher risk of term SGA, but no increased risk of preterm birth. The analyses restricted to women without reproductive experience revealed similar results. Before 2000 approximately half of pregnant women drank alcohol. This decreased to 39% in 2000-2004, and 14% in 2005-2011. Before 2000, every additional drink was associated with reduced mean birth weight, whereas in 2005-2011, the mean birth weight increased with increasing intake. The period-specific associations between low-to-moderate drinking and birth weight, which also were observed for term SGA, are indicative of bias. It is impossible to distinguish if the bias is attributable to unmeasured confounding, which change over time or cohort heterogeneity.
在怀孕期间轻度至中度饮酒的女性观察到其不良妊娠结局的风险低于不饮酒者。这被认为是由于偏倚所致。在一个包括来自九个欧洲队列的 193747 名活产单胎的合并样本中，我们研究了轻度至中度饮酒与早产、出生体重和足月出生的小于胎龄儿（足月 SGA）之间的关联。为了解决潜在的偏倚来源，我们将总样本中的关联与仅限于首次怀孕且在尝试怀孕后六个月内怀孕的女性的子样本进行了比较，并检查了关联是否随时间变化而变化。在总样本中，与不饮酒相比，每周饮酒不超过六杯与早产风险降低相关，而与出生体重或足月 SGA 无显著关联。每周饮酒六杯或更多与出生体重降低和足月 SGA 风险增加相关，但早产风险无增加。对无生殖经验的女性进行分析得出了相似的结果。2000 年之前，大约一半的孕妇饮酒。到 2000-2004 年降至 39%，2005-2011 年降至 14%。在 2000 年之前，每增加一杯酒与平均出生体重降低相关，而在 2005-2011 年，随着摄入量的增加，平均出生体重增加。在 2000 年之前，低至中度饮酒与出生体重之间的特定时期关联，也观察到与足月 SGA 相关，表明存在偏倚。无法确定这种偏倚是归因于无法测量的混杂因素，这些因素随时间或队列而异。
