子宫肌瘤是高普及率的良性肿瘤，它们是子宫切除术的主要理由，黑人女性的负担不成比例。以大豆为基础的婴儿配方奶粉含有植物雌激素，敏感发育期间的暴露可能会对发育中的子宫产生不利影响。啮齿动物的早期植物雌激素治疗导致女鼠子宫的不良反应，包括风险增加的 Eker 鼠肌瘤。有限的流行病学研究也暗示了大豆配方婴儿喂养与肌瘤的发生有关。本研究的目的是研究婴幼儿期的大豆配方喂养与成年期肌瘤发展之间的关系。我们在年龄在 23-35 岁的 1,610 名黑人/African-American 女性中评估了这种关联，他们参加了环境、生活方式和肌瘤研究计划 (SELF)。大豆配方喂养数据直接从参与者的母亲 (89%) 收集。在 5 年内的 4 次临床访问过程中进行了标准超声检查，以检测直径≥0.5厘米的肌瘤。我们使用 Cox 比例风险回归来估计大豆配方喂养与发病肌瘤之间的危险比 (HRs) 和 95% 置信区间 (CIs)，并对早期和成年因素进行了调整。肌瘤生长是以对比连续访问的肌瘤的对数体积的变化来计算的。在基线时没有肌瘤的 1,121 名参与者中，有 150 名 (13%) 在婴儿时期曾经喂养大豆配方奶粉，269 名 (24%) 发生了肌瘤。我们没有观察到被喂养大豆配方奶粉与发生肌瘤的风险有关联 (HR=1.08；95% CI：0.75、1.54)。然而，出生后 2 个月内和 >6 个月 (n=53) 喂养大豆配方奶粉的参与者与那些从未喂养大豆配方奶粉的参与者相比，患发病肌瘤的风险有所增加 (HR=1.56；95% CI：0.92、2.65)。肌瘤生长速率没有差异。该前瞻性肌瘤研究支持有限的人类数据，发现在婴儿时期使用基于大豆的配方奶粉与成年期超声识别的肌瘤发生有所增加。 https://doi.org/10.1289/EHP11089。

Uterine fibroids are highly prevalent, benign tumors. They are the leading indication for hysterectomy, and Black women are disproportionally burdened. Soy-based infant formula contains phytoestrogens, and exposure during sensitive developmental windows may adversely affect the developing uterus; early phytoestrogen treatment in rodent studies led to detrimental uterine effects, including increased fibroid risk in Eker rats. Limited epidemiological studies also have suggested increased fibroid development with soy formula infant feeding.The goal of this study was to examine the association between soy formula feeding in infancy and fibroid development in adulthood.We evaluated this association among 1,610 Black/African-American women age 23-35 y in the Study of Environment, Lifestyle & Fibroids (SELF). Soy formula feeding data was gathered directly from the participants' mothers (89%). A standardized ultrasound examination was conducted during 4 clinic visits over 5 y to detect fibroids ≥0.5cm in diameter. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between soy formula feeding and incident fibroids adjusted for early-life and adult factors. Fibroid growth was calculated as change in log-volume for fibroids matched at successive visits.Of 1,121 fibroid-free participants at baseline, 150 (13%) were ever fed soy formula as infants, and 269 (24%) developed incident fibroids. We did not observe an association between ever being fed soy formula and incident fibroid risk (HR=1.08; 95% CI: 0.75, 1.54). However, participants fed soy formula within 2 months of birth and for >6 months (n=53) had an elevated risk of fibroid incidence in comparison with those never fed soy formula (HR=1.56; 95% CI: 0.92, 2.65). Fibroid growth rates did not differ.Adding support to limited human data, this prospective fibroid study found that soy-based formula feeding during infancy was associated with a suggestive increase in risk of ultrasound-identified incident fibroids in adulthood. https://doi.org/10.1289/EHP11089.