Sharma Andrea J, Vesco Kimberly K, Bulkley Joanna, Callaghan William M, Bruce F Carol, Staab Jenny, Hornbrook Mark C, Berg Cynthia J
Division of Reproductive Health, National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, 4770 Buford Hwy NE, MS F-74, Atlanta, GA, 30341, USA.
U.S. Public Health Service Commissioned Corps, Atlanta, GA, USA.
Matern Child Health J. 2016 Oct;20(10):2030-6. doi: 10.1007/s10995-016-2032-y.
Objectives Low gestational weight gain (GWG) in the second and third trimesters has been associated with increased risk of preterm delivery (PTD) among women with a body mass index (BMI) < 25 mg/m(2). However, few studies have examined whether this association differs by the assumptions made for first trimester gain or by the reason for PTD. Methods We examined singleton pregnancies during 2000-2008 among women with a BMI < 25 kg/m(2) who delivered a live-birth ≥28 weeks gestation (n = 12,526). Women received care within one integrated health care delivery system and began prenatal care ≤13 weeks. Using antenatal weights measured during clinic visits, we interpolated GWG at 13 weeks gestation then estimated rate of GWG (GWGrate) during the second and third trimesters of pregnancy. We also estimated GWGrate using the common assumption of a 2-kg gain for all women by 13 weeks. We examined the covariate-adjusted association between quartiles of GWGrate and PTD (28-36 weeks gestation) using logistic regression. We also examined associations by reason for PTD [premature rupture of membranes (PROM), spontaneous labor, or medically indicated]. Results Mean GWGrate did not differ among term and preterm pregnancies regardless of interpolated or assumed GWG at 13 weeks. However, only with GWGrate estimated from interpolated GWG at 13 weeks, we observed a U-shaped relationship where odds of PTD increased with GWGrate in the lowest (OR 1.36, 95 % CI 1.10, 1.69) or highest quartile (OR 1.49, 95 % CI 1.20, 1.85) compared to GWGrate within the second quartile. Further stratifying by reason, GWGrate in the lowest quartile was positively associated with spontaneous PTD while GWGrate in the highest quartile was positively associated with PROM and medically indicated PTD. Conclusions Accurate estimates of first trimester GWG are needed. Common assumptions applied to all pregnancies may obscure the association between GWGrate and PTD. Further research is needed to fully understand whether these associations are causal or related to common antecedents.
在体重指数（BMI）<25mg/m²的女性中，孕中期和孕晚期孕期体重增加（GWG）过低与早产（PTD）风险增加有关。然而，很少有研究探讨这种关联是否因孕早期体重增加的假设或早产原因而异。方法：我们研究了2000年至2008年期间BMI<25kg/m²且分娩孕周≥28周的单胎妊娠女性（n = 12,526）。这些女性在一个综合医疗保健系统内接受护理，且在妊娠≤13周时开始产前检查。利用门诊就诊时测量的产前体重，我们推算出妊娠13周时的GWG，然后估计妊娠中期和晚期的GWG率（GWGrate）。我们还使用所有女性在13周时体重增加2kg这一常见假设来估计GWGrate。我们使用逻辑回归分析了GWGrate四分位数与PTD（妊娠28 - 36周）之间经协变量调整后的关联。我们还按早产原因[胎膜早破（PROM）、自然分娩或医学指征]分析了关联。结果：无论妊娠13周时的GWG是推算得出还是假设得出，足月妊娠和早产妊娠的平均GWGrate均无差异。然而，仅在根据妊娠13周时推算的GWG估计的GWGrate情况下，我们观察到一种U型关系，即与第二四分位数内的GWGrate相比，最低四分位数（OR 1.36，95%CI 1.10，1.69）或最高四分位数（OR 1.49，95%CI 1.20，1.85）的GWGrate时早产几率增加。按原因进一步分层，最低四分位数的GWGrate与自然早产呈正相关，而最高四分位数的GWGrate与胎膜早破和医学指征早产呈正相关。结论：需要准确估计孕早期的GWG。应用于所有妊娠的常见假设可能会掩盖GWGrate与PTD之间的关联。需要进一步研究以充分了解这些关联是因果关系还是与共同的先行因素有关。
