抽烟的问题？

Infants whose mothers smoke during pregnancy have low birthweight, are more likely to be born prematurely and are at greater risk of sudden infant death syndrome (page 181).Up to 2 years of age, infants with parents who smoke are more prone to lower respiratory tract illnesses and episodes of wheezing, and when older they have reduced lung volumes and higher carboxyhaemoglobin levels and are more likely to have asthma even at 14 years of age. It remains unclear whether this results from passive smoking in utero or from postnatal exposure to tobacco smoke in the home,9 but evidence for an in utero contribution is mounting, mediated by reduced innate immunity in the child born to a mother who smokes.10 The increased risk of lower respiratory tract illness in passive-smoking infants is believed to result from smaller airway calibre at birth causing a greater propensity to airway closure with the normal infective or allergic challenges of infancy. After a few years of normal growth, airway size increases sufficiently to reduce symptoms, and these children ‘grow out’ of their susceptibility to respiratory illness, although their lung function remains poorer than that of children who did not have lower airways disease in early life.

孕期吸烟婴儿出生时是低体重儿，婴儿更可能早产，婴儿猝死综合症的风险也更大（第181页）。婴儿期父母吸烟，2岁以下婴幼儿的更易患下呼吸道疾病和喘息发作，当年龄增大时父母吸烟，幼儿的肺容量减少，碳氧血红蛋白水平升高，即使在14岁时父母吸烟，孩子也更容易患哮喘。目前尚不清楚这是由于宫内被动吸烟还是出生后在家中暴露在烟草烟雾中⁹，但是越来越多的证据表明孕妇吸烟的婴儿先天免疫功能低下¹⁰。有研究者认为，被动吸烟的婴儿患下呼吸道疾病的风险增加与由于出生时气道管径小，在正常的感染或过敏下，致使他们的气道更易缩窄闭陷有关。随着年龄增长，尽管这些婴幼儿的肺功能仍然比那些在生命早期没有下呼吸道疾病的儿童差，但由于其气道管径增加可致喘息等相关症状减轻。

我自己觉得是三个并列谓语，要是三个并列谓语，不就是所有的“孕期吸烟”的母亲生下来的孩子都是“低体重儿”？有那么绝对吗？连个may也不加？

婴儿期父母吸烟，2岁以下婴幼儿的更易患下呼吸道疾病和喘息发作，当年龄增大时父母吸烟，幼儿的肺容量减少，碳氧血红蛋白水平升高，即使在14岁时父母吸烟，孩子也更容易患哮喘？对吗？

Up to 2 years of age, infants with parents who smoke are more prone to lower respiratory tract illnesses and episodes of wheezing

婴儿期父母吸烟，2岁以下婴幼儿的更易患下呼吸道疾病和喘息发作? 还是“父母吸烟使2岁以下婴幼儿患气道疾病和和喘息发作风险增加”？谢谢

1岁以内的才能叫Infants吧？所以我觉得“婴儿期父母吸烟，2岁以下婴幼儿的更易患下呼吸道疾病和喘息发作”