Lindam Anna, Johansson Stefan, Stephansson Olof, Wikström Anna-Karin, Cnattingius Sven
Am J Epidemiol. 2016 Jul 15;184(2):98-105. doi: 10.1093/aje/kww046. Epub 2016 Jun 29.
In a population-based case-control study, we investigated whether familial confounding influenced the associations between maternal overweight/obesity and risks of stillbirth and infant mortality by including both population and sister controls. Using nationwide data from the Swedish Medical Birth Register (1992-2011), we included all primiparous women with singleton births who also had a sister with a first birth during that time period. We used logistic regression analyses to calculate odds ratios (and 95% confidence intervals) adjusted for maternal age, height, smoking habits, education, and time period (5-year groups) of child's birth. Body mass index (BMI) was calculated as weight (kg)/height (m)(2) Compared with population controls with a normal BMI (18.5-24.9), stillbirth risk increased with increasing BMI (BMI 25-29.9: odds ratio (OR) = 1.51 (95% confidence interval (CI): 1.21, 1.89); BMI 30-34.9: OR = 1.77 (95% CI: 1.24, 2.50); BMI ≥35: OR = 3.16 (95% CI: 2.10, 4.76)). The sister case-control analyses revealed similar results. Offspring of obese women (BMI ≥30) had an increased risk of infant mortality when population controls were used (OR = 2.41, 95% CI: 1.83, 3.16), and an even higher risk was obtained when sister controls were used (OR = 4.04, 95% CI: 2.25, 7.25). We conclude that obesity in early pregnancy is associated with increased risks of stillbirth and infant mortality independently of genetic and early environmental risk factors shared within families.
在一项基于人群的病例对照研究中，我们通过纳入人群对照和姐妹对照，调查了家族混杂因素是否会影响孕产妇超重/肥胖与死产风险及婴儿死亡率之间的关联。利用瑞典医疗出生登记处（1992 - 2011年）的全国性数据，我们纳入了所有单胎初产妇，她们在此期间还有一个首次生育的姐妹。我们使用逻辑回归分析来计算经孕产妇年龄、身高、吸烟习惯、教育程度以及孩子出生时间段（5年分组）调整后的比值比（及95%置信区间）。体重指数（BMI）计算为体重（千克）/身高（米）²。与BMI正常（18.5 - 24.9）的人群对照相比，死产风险随BMI升高而增加（BMI 25 - 29.9：比值比（OR）= 1.51（95%置信区间（CI）：1.21，1.89）；BMI 30 - 34.9：OR = 1.77（95% CI：1.24，2.50）；BMI≥35：OR = 3.16（95% CI：2.10，4.76））。姐妹病例对照分析得出了类似结果。当使用人群对照时，肥胖女性（BMI≥30）的后代婴儿死亡风险增加（OR = 2.41，95% CI：1.83，3.16），而使用姐妹对照时风险更高（OR = 4.04，95% CI：2.25，7.25）。我们得出结论，孕早期肥胖与死产和婴儿死亡风险增加相关，且独立于家族内共享的遗传和早期环境风险因素。
