Howard David L, Marshall Susan S, Kaufman Jay S, Savitz David A
Carolina Population Center, 211 W Cameron Ave, Chapel Hill, NC 27516, USA.
Pediatrics. 2006 Nov;118(5):e1399-405. doi: 10.1542/peds.2006-0665.
Black women in the United States are more likely to give birth to preterm and low birth-weight infants than their white counterparts, but little is known about variation in birth outcomes within the black population. This study aimed to test the hypothesis that the risk of low birth weight and preterm birth within the black population varies by maternal ancestry and nativity.
We conducted a retrospective cohort study using New York City birth records. All of the recorded live births to black women occurring in New York City between January 1, 1998, and December 31, 2002 (N = 168,039), were divided into the following self-reported ancestry groups: African, American, Asian, Cuban, European, Puerto Rican, South and Central American (excluding Brazilian), and West Indian and Brazilian. To estimate adjusted risk ratios for low birth weight (weight at birth <2500 g) and preterm birth (gestational age at delivery <37 weeks, based on clinical estimate), we ran 3 models for each outcome, using negative binomial regression and Poisson regression with robust SE estimation. All of the models used blacks reporting American ancestry as the reference group. The first model included ancestry as the primary exposure variable along with covariates that included maternal age, parity, smoking, and education, as well as paternal education and race. Nativity (US- or foreign-born) was included in the second model, and terms representing interaction effects between ancestry and nativity were included in the third model.
There was substantial variation in risks of preterm birth and low birth weight among the black subgroups, with all of the groups having lower risks than the American black reference group, even after adjusting for maternal risk factors and other covariates. Risk ratios for low birth weight ranged from 0.55 among South/Central Americans to 0.91 among Cubans; risk ratios for preterm birth showed a similar pattern. Nativity was also associated with low birth weight and preterm birth; births to foreign-born women were less likely to be preterm or low birth weight than births to US-born women. Furthermore, nativity effects varied by ancestry group, with foreign-born status inversely associated with poor birth outcomes among South/Central Americans but not among West Indians/Brazilians.
Important health differences may be masked in studies that treat black women in America as a homogeneous group and do not take ethnic variation and nativity into account.
在美国，黑人女性比白人女性更易生出早产及低体重婴儿，但对于黑人人群中出生结局的差异却知之甚少。本研究旨在检验以下假设：黑人人群中低体重和早产风险因母亲的祖籍和出生地而异。
我们利用纽约市的出生记录进行了一项回顾性队列研究。1998年1月1日至2002年12月31日期间在纽约市记录的所有黑人女性的活产（N = 168,039），被分为以下自我报告的祖籍组：非洲、美国、亚洲、古巴、欧洲、波多黎各、南美和中美洲（不包括巴西），以及西印度群岛和巴西。为了估计低体重（出生体重<2500克）和早产（根据临床估计，分娩时孕周<37周）的调整风险比，我们针对每个结局运行了3个模型，使用负二项回归和带有稳健标准误估计的泊松回归。所有模型均将报告美国祖籍的黑人作为参照组。第一个模型将祖籍作为主要暴露变量，同时纳入协变量，包括母亲年龄、产次、吸烟情况和教育程度，以及父亲的教育程度和种族。第二个模型纳入了出生地（美国出生或外国出生），第三个模型纳入了代表祖籍和出生地之间交互作用的项。
黑人亚组之间早产和低体重风险存在显著差异，即使在调整了母亲风险因素和其他协变量后，所有组的风险均低于美国黑人参照组。低体重的风险比范围从南美/中美洲人群的0.55到古巴人群的0.91；早产的风险比呈现类似模式。出生地也与低体重和早产有关；外国出生女性的分娩比美国出生女性的分娩更不易早产或低体重。此外，出生地的影响因祖籍组而异，外国出生状态与南美/中美洲人群中不良出生结局呈负相关，但与西印度群岛/巴西人群无关。
在美国，将黑人女性视为一个同质群体且未考虑种族差异和出生地的研究可能掩盖了重要的健康差异。
