Slone Epidemiology Center, Boston University, Boston, MA 02215, USA.
Epidemiology. 2010 Mar;21(2):243-52. doi: 10.1097/EDE.0b013e3181cb61a9.
Studies of the association of prepregnancy body mass index (BMI) and preterm birth have been inconclusive, and no studies have examined the effect of central adiposity on risk. There is also uncertainty about optimal gestational weight gain among Black women.
Using self-reported prospective data from the Black Women's Health Study, we investigated the relation of preterm birth to prepregnancy BMI (kg/m), waist circumference, and gestational weight gain among 7840 singletons born to black women, ages 21-44, during 1995-2003. We compared mothers of 1114 infants born 3 or more weeks early (597 spontaneous preterm births and 517 medically-indicated preterm births) with mothers of 6726 term infants. We used generalized estimating equation models to derive multivariable odds ratios (ORs) and 95% confidence intervals (CIs).
Relative to normal weight women (BMI: 18.5-24.9), underweight women (BMI: <18.5) were at increased risk of both preterm birth subtypes; obese women (BMI > or = 30.0) were at increased risk of medically-indicated preterm birth and very early spontaneous preterm birth (<32 weeks' gestation). Waist circumference, a measure of central adiposity, was positively associated with medically-indicated preterm birth. Among obese women, average gestational weight gain in the second and third trimesters of <0.4 or >0.6 lbs/wk was associated with an increased risk of both preterm birth subtypes.
Our data suggest that underweight increases risk of both preterm birth subtypes, while obesity increases risk of medically-indicated preterm birth and only a subgroup of spontaneous preterm births (<32 weeks' gestation). Central adiposity was an independent risk factor for medically-indicated preterm birth only. Among obese women, gestational weight gain within the range recommended by the 2009 Institute of Medicine report (0.4-0.6 lbs/week in the second and third trimesters) was associated with the lowest risk of preterm birth.
关于孕前体重指数（BMI）与早产之间的关系的研究尚无定论，也没有研究探讨中心性肥胖对风险的影响。黑人女性的最佳孕期体重增加也存在不确定性。
利用黑人女性健康研究中的自我报告前瞻性数据，我们调查了 7840 名黑人女性所生的单胎婴儿中，早产与孕前 BMI（kg/m）、腰围和孕期体重增加之间的关系，这些婴儿出生于 1995-2003 年，年龄在 21-44 岁之间。我们将 1114 名早产 3 周或以上的婴儿的母亲（597 例自发性早产和 517 例医学指征性早产）与 6726 名足月婴儿的母亲进行了比较。我们使用广义估计方程模型得出多变量比值比（OR）和 95%置信区间（CI）。
与正常体重女性（BMI：18.5-24.9）相比，体重不足的女性（BMI：<18.5）两种早产亚型的风险均增加；肥胖女性（BMI≥30.0）的医学指征性早产和极早期自发性早产（<32 周妊娠）的风险增加。腰围是衡量中心性肥胖的指标，与医学指征性早产呈正相关。在肥胖女性中，第二和第三个三个月的平均增重<0.4 或>0.6 磅/周与两种早产亚型的风险增加相关。
我们的数据表明，体重不足会增加两种早产亚型的风险，而肥胖会增加医学指征性早产的风险，并且仅增加极早期自发性早产（<32 周妊娠）的风险。中心性肥胖仅为医学指征性早产的独立危险因素。在肥胖女性中，孕期体重增加在 2009 年美国医学研究所报告（第二和第三个三个月增重 0.4-0.6 磅/周）推荐的范围内与早产风险最低相关。
