Kaiser Permanente Division of Research, 2000 Broadway, Oakland, CA, 94612, USA.
Division of Maternal and Child Health, University of California, Berkeley, School of Public Health, 2121 Berkeley Way #5302, Berkeley, CA, 94720, USA.
BMC Pediatr. 2019 Aug 9;19(1):277. doi: 10.1186/s12887-019-1661-x.
Early puberty is associated with higher risk of adverse health and behavioral outcomes throughout adolescence and adulthood. US girls are experiencing earlier puberty with substantial racial/ethnic differences. We examined the association between breastfeeding and pubertal timing to identify modifiable risk factors of early puberty and potential sources of racial/ethnic differences in the timing of pubertal development.
A prospective cohort study of 3331 racially/ethnically diverse girls born at Kaiser Permanente Northern California (KPNC) between 2004 and 06. All data were obtained from KPNC electronic clinical and administrative datasets. Mother-reported duration of breastfeeding was obtained from questionnaires administered at each 'well-baby' check-up exam throughout the baby's first year and categorized as 'Not breastfed', 'Breastfed < 6 months', and 'Breastfed ≥ 6 months'. Pubertal development data used Tanner stages assessed by pediatricians during routine pediatric checkups starting at age 6. Pubertal onset was defined as transition from Tanner Stage 1 to Tanner Stage 2+ for breast (thelarche) and pubic hair (pubarche). Weibull regression models accommodating for left, right, and interval censoring were used in all analyses. Models were adjusted for maternal age, education, race/ethnicity, parity and prepubertal body mass index (BMI). We also examined race/ethnicity as a potential effect modifier of these associations.
Not breastfeeding was associated with earlier onset of breast and pubic hair development compared to breastfeeding ≥6 months (adjusted hazard ratio [HR]: 1.25; 95% confidence interval [CI]: 1.07-1.46; HR: 1.24; 95% CI: 1.05-1.46, respectively). Breastfeeding for < 6 months was also associated with the risk of earlier pubic hair development (HR: 1.14; 95% CI: 1.00-1.30, compared to breastfeeding ≥6 months). Inclusion of girls' prepubertal BMI slightly attenuated the association between breastfeeding and timing of breast onset but remained significant. The association between not breastfeeding and early breast development may be stronger among African American girls (HR: 1.92; 95% CI: 1.01-3.66, no breastfeeding vs. ≥6 months) than other racial/ethnic groups.
Breastfeeding is an independent predictor of pubertal onset in girls, and the strength of the association may vary by race/ethnicity. Providing breastfeeding support and lactation education for high risk mothers may help prevent earlier pubertal onset and promote positive health outcomes later in life.
青春期提前与青春期和成年期的不良健康和行为结果风险增加有关。美国女孩的青春期提前，且存在显著的种族/民族差异。我们研究了母乳喂养与青春期时间的关系，以确定青春期提前的可改变风险因素和青春期发育时间种族/民族差异的潜在来源。
这是一项对 2004 年至 2006 年期间在 Kaiser Permanente Northern California（KPNC）出生的 3331 名不同种族/民族的女孩进行的前瞻性队列研究。所有数据均来自 KPNC 的电子临床和行政数据集。通过在婴儿第一年的每次“健康婴儿”检查中进行的问卷调查获得母亲报告的母乳喂养持续时间，并分为“未母乳喂养”、“母乳喂养<6 个月”和“母乳喂养≥6 个月”。使用儿科医生在常规儿科检查中评估的 Tanner 分期来获取青春期发育数据，从 6 岁开始。青春期开始被定义为乳房（乳房发育）和阴毛（阴毛发育）从 Tanner 分期 1 过渡到 Tanner 分期 2+。所有分析均使用 Weibull 回归模型，该模型考虑了左侧、右侧和区间 censoring。模型调整了母亲的年龄、教育程度、种族/民族、产次和青春期前的体重指数（BMI）。我们还研究了种族/民族是否是这些关联的潜在效应修饰因子。
与母乳喂养≥6 个月相比，未母乳喂养与乳房和阴毛发育的更早开始相关（调整后的风险比 [HR]：1.25；95%置信区间 [CI]：1.07-1.46；HR：1.24；95% CI：1.05-1.46）。母乳喂养<6 个月也与阴毛发育的风险增加相关（与母乳喂养≥6 个月相比，HR：1.14；95% CI：1.00-1.30）。纳入女孩青春期前的 BMI 略微减弱了母乳喂养与乳房起始时间之间的关联，但仍然具有统计学意义。未母乳喂养与早期乳房发育之间的关联在非裔美国女孩中可能更强（HR：1.92；95% CI：1.01-3.66，未母乳喂养与≥6 个月），而非其他种族/民族。
母乳喂养是女孩青春期开始的独立预测因素，其关联的强度可能因种族/民族而异。为高风险母亲提供母乳喂养支持和哺乳教育可能有助于预防青春期提前，并促进以后的健康结果。
