Background

Being overweight is an important risk factor for Gestational Diabetes Mellitus (GDM), but the underlying mechanisms are not understood. Weight change between pregnancies has been suggested to be an independent mechanism behind GDM. We assessed the risk for GDM in second pregnancy by change in Body Mass Index (BMI) from first to second pregnancy and whether BMI and gestational weight gain modified the risk.

Methods and findings

In this observational cohort, we included 24,198 mothers and their 2 first pregnancies in data from the Medical Birth Registry of Norway (2006–2014). Weight change, defined as prepregnant BMI in second pregnancy minus prepregnant BMI in first pregnancy, was divided into 6 categories by units BMI (kilo/square meter). Relative risk (RR) estimates were obtained by general linear models for the binary family and adjusted for maternal age at second delivery, country of birth, education, smoking in pregnancy, interpregnancy interval, and year of second birth. Analyses were stratified by BMI (first pregnancy) and gestational weight gain (second pregnancy). Compared to women with stable BMI (−1 to 1), women who gained weight between pregnancies had higher risk of GDM—gaining 1 to 2 units: adjusted RR 2.0 (95% CI 1.5 to 2.7), 2 to 4 units: RR 2.6 (2.0 to 3.5), and ≥4 units: RR 5.4 (4.0 to 7.4). Risk increased significantly both for women with BMI below and above 25 at first pregnancy, although it increased more for the former group. A limitation in our study was the limited data on BMI in 2 pregnancies.

Conclusions

The risk of GDM increased with increasing weight gain from first to second pregnancy, and more strongly among women with BMI < 25 in first pregnancy. Our results suggest weight change as a metabolic mechanism behind the increased risk of GDM, thus weight change should be acknowledged as an independent factor for screening GDM in clinical guidelines. Promoting healthy weight from preconception through the postpartum period should be a target.

中文翻译：

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妊娠期糖尿病和妊娠期体重变化：一项基于人群的队列研究

背景

超重是妊娠糖尿病（GDM）的重要危险因素，但其潜在机制尚不清楚。妊娠之间体重的变化已被认为是GDM背后的独立机制。我们通过从第一次妊娠到第二次妊娠的体重指数（BMI）的变化以及BMI和妊娠体重增加是否改变了该风险来评估第二次妊娠中GDM的风险。

方法和发现

在这个观察性队列中，我们从挪威医疗出生登记处（2006-2014年）收集了24,198名母亲及其两次初次怀孕。体重变化定义为第二次怀孕的孕妇BMI减去第一次怀孕的孕妇BMI，按BMI单位（千/平方米）分为6类。通过二元家庭的一般线性模型获得相对风险（RR）估计值，并根据第二胎分娩的产妇年龄，出生国，受教育程度，怀孕期间吸烟，妊娠间隔和第二胎年进行了调整。根据BMI（第一次妊娠）和妊娠体重增加（第二次妊娠）对分析进行分层。与BMI稳定的妇女（-1：1）相比，怀孕之间体重增加的妇女发生GDM的风险更高-获得1至2单位：调整后的RR为2.0（95％CI为1.5至2.7），2至4单位为：RR 2.6 （2.0至3。5）和≥4个单位：RR 5.4（4.0至7.4）。初次怀孕时BMI低于25或高于25的女性的危险性显着增加，尽管前一组的危险性增加更多。我们研究的局限性是2例孕妇的BMI数据有限。

结论

从第一次妊娠到第二次妊娠体重增加，GDM的风险增加，并且第一次妊娠BMI <25的女性中GDM的危险更大。我们的结果表明，体重变化是GDM风险增加后的代谢机制，因此，在临床指南中应将体重变化视为筛查GDM的独立因素。从孕前到产后增加健康体重应该成为目标。