Meta-Analysis Group, MRC Clinical Trials Unit at UCL, Institute of Clinical Trials & Methodology, 90 High Holborn, 2nd Floor, London, WC1V 6LJ, UK.
Women's Health Research Unit, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
BMC Pregnancy Childbirth. 2019 Sep 2;19(1):322. doi: 10.1186/s12884-019-2472-7.
High Body Mass Index (BMI) and gestational weight gain (GWG) affect an increasing number of pregnancies. The Institute of Medicine (IOM) has issued recommendations on the optimal GWG for women according to their pre-pregnancy BMI (healthy, overweight or obese). It has been shown that pregnant women rarely met the recommendations; however, it is unclear by how much. Previous studies also adjusted the analyses for various women's characteristics making their comparison challenging.
We analysed individual participant data (IPD) of healthy women with a singleton pregnancy and a BMI of 18.5 kg/m or more from the control arms of 36 randomised trials (16 countries). Adjusted odds ratios (aOR) and 95% confidence intervals (CI) were used to describe the association between GWG outside (above or below) the IOM recommendations (2009) and risks of caesarean section, preterm birth, and large or small for gestational age (LGA or SGA) infants. The association was examined overall, within the BMI categories and by quartile of GWG departure from the IOM recommendations. We obtained aOR using mixed-effects logistic regression, accounting for the within-study clustering and a priori identified characteristics.
Out of 4429 women (from 33 trials) meeting the inclusion criteria, two thirds gained weight outside the IOM recommendations (1646 above; 1291 below). The median GWG outside the IOM recommendations was 3.1 kg above and 2.7 kg below. In comparison to GWG within the IOM recommendations, GWG above was associated with increased odds of caesarean section (aOR 1.50; 95%CI 1.25, 1.80), LGA (2.00; 1.58, 2.54), and reduced odds of SGA (0.66; 0.50, 0.87); no significant effect on preterm birth was detected. The relationship between GWG below the IOM recommendation and caesarean section or LGA was inconclusive; however, the odds of preterm birth (1.94; 1.31, 2.28) and SGA (1.52; 1.18, 1.96) were increased.
Consistently with previous findings, adherence to the IOM recommendations seem to help achieve better pregnancy outcomes. Nevertheless, even in the context of clinical trials, women find it difficult to adhere to them. Further research should focus on identifying ways of achieving a healthier GWG as defined by the IOM recommendations.
高身体质量指数（BMI）和妊娠体重增加（GWG）影响着越来越多的妊娠。医学研究所（IOM）已经根据孕妇的孕前 BMI（健康、超重或肥胖）发布了关于最佳 GWG 的建议。研究表明，孕妇很少符合这些建议；然而，具体情况并不清楚。之前的研究也针对不同女性的特征进行了分析，这使得它们的比较具有挑战性。
我们分析了来自 36 项随机试验（来自 16 个国家）的控制组中 BMI 为 18.5kg/m 或以上的健康单胎妊娠女性的个体参与者数据（IPD）。使用调整后的优势比（aOR）和 95%置信区间（CI）来描述 GWG 超出（高于或低于）IOM 建议（2009 年）与剖宫产、早产以及大于胎龄儿（LGA）或小于胎龄儿（SGA）的风险之间的关系。在整个研究、BMI 类别内以及 GWG 偏离 IOM 建议的四分位距内，我们都对这种关联进行了检查。我们使用混合效应逻辑回归获得了 aOR，同时考虑了研究内的聚类和事先确定的特征。
在符合纳入标准的 4429 名女性（来自 33 项试验）中，有三分之二的女性体重增加超过了 IOM 建议（1646 名高于建议；1291 名低于建议）。GWG 超出 IOM 建议的中位数为 3.1kg 以上和 2.7kg 以下。与 GWG 符合 IOM 建议相比，GWG 高于建议与剖宫产（aOR 1.50；95%CI 1.25，1.80）、LGA（2.00；1.58，2.54）的几率增加相关，与 SGA（0.66；0.50，0.87）的几率降低相关；未检测到对早产的显著影响。GWG 低于 IOM 建议与剖宫产或 LGA 之间的关系尚无定论；然而，早产（1.94；1.31，2.28）和 SGA（1.52；1.18，1.96）的几率增加。
与之前的研究结果一致，遵循 IOM 建议似乎有助于获得更好的妊娠结局。然而，即使在临床试验的背景下，女性也很难遵守这些建议。进一步的研究应集中于寻找实现 IOM 建议所定义的更健康 GWG 的方法。
