School of Public Health Peking University Health Science Center, 38 Xueyuan Rd Haidian District, 100191 Beijing, People's Republic of China.
Arch Gynecol Obstet. 2011 Oct;284(4):813-9. doi: 10.1007/s00404-010-1740-6. Epub 2010 Nov 11.
To determine the association between maternal body mass index (BMI) in early pregnancy and the risk of preterm birth (PTB) in Chinese women.
Data were obtained from a population-based perinatal care program in China during 1993-2005. Women whose height and weight information was recorded at the first prenatal visit in the first trimester of pregnancy and delivered a singleton live infant were selected. Women with multiple gestations, stillbirths, delivery before 28 weeks or after 44 weeks of gestation, and infants affected by major external birth defects were excluded. BMI was categorized as underweight (less than 18.5 kg/m(2)), normal weight (18.5-23.9 kg/m(2)), overweight (24-27.9 kg/m(2)), and obese (≥28 kg/m(2)) based on BMI classification criteria for Chinese. Logistic regression analysis was conducted to adjust for potential confounders, such as maternal age, education, occupation, city or county, gender of infant, and year of delivery.
A total of 353,477 women were selected. The incidence of preterm birth in women who were underweight, normal weight, overweight, obese was 3.69% (3.61-3.76%), 3.59% (3.55-3.62%), 3.83% (3.71-3.96%), 4.90% (4.37-5.43%), respectively. The incidence of elective preterm birth, overweight, and obesity increased remarkably during 2000-2005 compared with that during 1993-1996. After having adjusted for potential confounders including maternal age, maternal occupation, education, city or county, gender of the infant and year of birth, the risk of PTB increased significantly with BMI (P < 0.05). Among nulliparae, the risk of elective preterm birth increased with increasing BMI. Nulliparae who were underweight were less likely to deliver elective preterm births (OR = 0.89, 95% CI 0.80-0.98). Nulliparae who were overweight and obese in early pregnancy were at a greater risk of elective PTB than normal weight nulliparae (for the overweight OR = 1.36, 95% CI 1.18-1.56, for the obese OR = 2.94, 95% CI 2.04-4.25).
In this study, indigenous Chinese cohort women who are overweight, obese, and nulliparous are at an increased risk of elective preterm birth.
探讨中国孕妇孕早期体质量指数（BMI）与早产（PTB）风险的关系。
数据来自于 1993-2005 年中国一项基于人群的围产保健项目。选择在孕早期第一次产前检查时记录身高和体重，并分娩单胎活婴的孕妇。排除多胎妊娠、死胎、孕周<28 周或>44 周分娩、有严重出生缺陷的婴儿。根据中国 BMI 分类标准，BMI<18.5kg/m2 为消瘦，18.5-23.9kg/m2 为正常体重，24-27.9kg/m2 为超重，≥28kg/m2 为肥胖。采用多因素 logistic 回归分析调整潜在混杂因素，如孕妇年龄、文化程度、职业、城乡、婴儿性别和分娩年份等。
共纳入 353477 名孕妇。消瘦、正常体重、超重和肥胖孕妇的早产发生率分别为 3.69%（3.61%-3.76%）、3.59%（3.55%-3.62%）、3.83%（3.71%-3.96%）和 4.90%（4.37%-5.43%）。2000-2005 年与 1993-1996 年相比，选择性早产、超重和肥胖的发生率显著增加。调整孕妇年龄、职业、文化程度、城乡、婴儿性别和分娩年份等混杂因素后，BMI 与 PTB 风险呈显著正相关（P<0.05）。在初产妇中，随着 BMI 的增加，选择性早产的风险显著增加。孕早期消瘦的初产妇发生选择性早产的风险较低（OR=0.89，95%CI 0.80-0.98）。与正常体重的初产妇相比，孕早期超重和肥胖的初产妇发生选择性 PTB 的风险更高（超重 OR=1.36，95%CI 1.18-1.56，肥胖 OR=2.94，95%CI 2.04-4.25）。
在这项研究中，中国本土孕妇超重、肥胖和初产妇发生选择性早产的风险增加。
