Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montreal, Quebec, Canada.
Department of Obstetrics & Gynaecology, University of British Columbia, Vancouver, British Columbia Canada.
Ann Epidemiol. 2021 Aug;60:45-52. doi: 10.1016/j.annepidem.2021.04.010. Epub 2021 Apr 22.
Researchers are interested in studying longitudinal patterns of gestational weight gain, yet this requires daily/weekly weights, and maternal weight is measured only during prenatal visits. We evaluated the relative accuracy and precision of methods for estimating maternal weight gain between prenatal visits among twin and singleton pregnancies.
We analyzed cohorts of dichorionic twin and singleton pregnancies delivered from 1998-2013 in Pittsburgh, Pennsylvania. We mimicked a typical study by retaining pre-pregnancy, first prenatal visit, glucose screening visit, and delivery weights, using these to fit interpolation models, estimating weight throughout pregnancy using 16 different methods, and calculating the difference in kilograms between predicted and measured values among remaining weights. We evaluated the performance of each model by calculating root mean squared error (RMSE).
RMSE ranged from 1.55 to 6.09 kg in twins (n = 2067) and 1.45 to 4.87 kg in singletons (n = 7331). The most accurate and precise methods incorporated restricted cubic splines, random intercepts and slopes for pregnancy, and internal knots demarcating trimesters/quantiles (RMSE = 1.55/1.56 kg in twins, 1.45/1.45 kg in singletons), while individual-level linear interpolation between proximal measurements also performed well.
Accuracy and precision of methods for estimating maternal weight gain between measurements differed by model, and were best among individually-tailored and flexible models.
研究人员有兴趣研究妊娠体重增加的纵向模式，但这需要每天/每周的体重数据，而孕妇体重仅在产前检查时测量。我们评估了在双胎和单胎妊娠中，在产前检查之间估计孕妇体重增加的方法的相对准确性和精密度。
我们分析了宾夕法尼亚州匹兹堡市 1998-2013 年分娩的双胎和单胎妊娠队列。我们通过保留孕前、第一次产前检查、葡萄糖筛查检查和分娩时的体重，使用这些数据拟合插值模型，使用 16 种不同的方法来估计整个孕期的体重，并计算剩余体重的预测值和测量值之间的公斤数差异。我们通过计算均方根误差（RMSE）来评估每种模型的性能。
双胞胎（n=2067）的 RMSE 范围为 1.55 至 6.09 公斤，单胎（n=7331）的 RMSE 范围为 1.45 至 4.87 公斤。最准确和最精确的方法包括限制三次样条、妊娠的随机截距和斜率以及标记三个月/分位数的内部结（双胞胎的 RMSE=1.55/1.56 公斤，单胎的 RMSE=1.45/1.45 公斤），而个体水平上的近端测量值之间的线性插值也表现良好。
在测量之间估计孕妇体重增加的方法的准确性和精密度因模型而异，在个体化定制和灵活的模型中最佳。
