Maternal smoking during pregnancy and early development of overweight and growth deficit in children: an analysis of survival

Abstract Objectives: to evaluate the association between smoking during pregnancy and nutritional status. Methods: cohort study with a sample of 460 children in the baseline. The children were assessed four times, being measured for weight and length to be converted in indexes length forage (L/A) and body mass index forage (BMI/A) in Z-score. The time until occurrence of growth deficit and overweight was calculated in days and compared to maternal smoking during pregnancy. To assess the association between smoking during pregnancy and the outcomes, a Hazard Ratio by Cox regression was obtained, adjusting by confounding variables selected from Directed Acyclic Graphs (DAG). Results: the time until occurrence of growth deficit and overweight was lower in children whose mothers smoked during pregnancy. Smoking during pregnancy was a risk factor for length deficit (HR = 2.84; CI95% = 1.42 to 5.70) and for overweight (HR = 1.96; CI95% = 1, 09 to 3.53), even after the adjustment. Conclusions: maternal smoking was a changeable factor associated with anthropometric outcomes, which demonstrates the need for actions to combat smoking during pregnancy in order to prevent early nutritional deviations.

摘要
研究目的：探讨孕期吸烟与儿童营养状况之间的关联。
研究方法：本研究为队列研究，基线纳入460名儿童作为研究样本。研究共开展四次随访评估，对儿童的体重与身长进行测量，并将测量值转换为年龄别身长（length-for-age, L/A）与年龄别体质指数（BMI-for-age, BMI/A）的Z评分。以生长发育缺陷与超重的发生时间（以天为单位）作为结局指标，对比孕期吸烟母亲与非吸烟母亲所生儿童的结局差异。为分析孕期吸烟与结局指标间的关联，采用Cox比例风险回归模型计算风险比（HR），并通过有向无环图（Directed Acyclic Graphs, DAG）筛选混杂变量进行校正。
研究结果：孕期吸烟母亲所生儿童发生生长发育缺陷与超重的时间更早。校正混杂变量后，孕期吸烟仍是身长发育缺陷（HR=2.84；95%置信区间[CI]：1.42~5.70）与超重（HR=1.96；95%置信区间[CI]：1.09~3.53）的危险因素。
研究结论：母亲孕期吸烟是与儿童人体测量学结局相关的可干预因素，提示需开展针对孕期吸烟的干预措施，以预防早期营养偏差。